Ground State Geometries of Polyacetylene Chains from Many-Particle Quantum Mechanics.
Barborini, Matteo; Guidoni, Leonardo
2015-09-08
Due to the crucial role played by electron correlation, the accurate determination of ground state geometries of π-conjugated molecules is still a challenge for many quantum chemistry methods. Because of the high parallelism of the algorithms and their explicit treatment of electron correlation effects, Quantum Monte Carlo calculations can offer an accurate and reliable description of the electronic states and of the geometries of such systems, competing with traditional quantum chemistry approaches. Here, we report the structural properties of polyacetylene chains H-(C₂H₂)(N)-H up to N = 12 acetylene units, by means of Variational Monte Carlo (VMC) calculations based on the multi-determinant Jastrow Antisymmetrized Geminal Power (JAGP) wave function. This compact ansatz can provide for such systems an accurate description of the dynamical electronic correlation as recently detailed for the 1,3-butadiene molecule [J. Chem. Theory Comput. 2015 11 (2), 508-517]. The calculated Bond Length Alternation (BLA), namely the difference between the single and double carbon bonds, extrapolates, for N → ∞, to a value of 0.0910(7) Å, compatible with the experimental data. An accurate analysis was able to distinguish between the influence of the multi-determinantal AGP expansion and of the Jastrow factor on the geometrical properties of the fragments. Our size-extensive and self-interaction-free results provide new and accurate ab initio references for the structures of the ground state of polyenes.
Application of artificial intelligence to search ground-state geometry of clusters
Lemes, Maurício Ruv; Marim, L. R.; dal Pino, A.
2002-08-01
We introduce a global optimization procedure, the neural-assisted genetic algorithm (NAGA). It combines the power of an artificial neural network (ANN) with the versatility of the genetic algorithm. This method is suitable to solve optimization problems that depend on some kind of heuristics to limit the search space. If a reasonable amount of data is available, the ANN can ``understand'' the problem and provide the genetic algorithm with a selected population of elements that will speed up the search for the optimum solution. We tested the method in a search for the ground-state geometry of silicon clusters. We trained the ANN with information about the geometry and energetics of small silicon clusters. Next, the ANN learned how to restrict the configurational space for larger silicon clusters. For Si10 and Si20, we noticed that the NAGA is at least three times faster than the ``pure'' genetic algorithm. As the size of the cluster increases, it is expected that the gain in terms of time will increase as well.
Study of the Ground-State Geometry of Silicon Clusters Using Artificial Neural Networks
Directory of Open Access Journals (Sweden)
M.R. Lemes
2002-09-01
Full Text Available Theoretical determination of the ground-state geometry of Si clusters is a difficult task. As the number of local minima grows exponentially with the number of atoms, to find the global minimum is a real challenge. One may start the search procedure from a random distribution of atoms but it is probably wiser to make use of any available information to restrict the search space. Here, we introduce a new approach, the Assisted Genetic Optimization (AGO that couples an Artificial Neural Network (ANN to a Genetic Algorithm (GA. Using available information on small Silicon clusters, we trained an ANN to predict good starting points (initial population for the GA. AGO is applied to Si10 and Si20 and compared to pure GA. Our results indicate: i AGO is, at least, 5 times faster than pure GA in our test case; ii ANN training can be made very fast and successfully plays the role of an experienced investigator; iii AGO can easily be adapted to other optimization problems.
Bengtsson, Ingemar; Zyczkowski, Karol
2007-12-01
Preface; 1. Convexity, colours and statistics; 2. Geometry of probability distributions; 3. Much ado about spheres; 4. Complex projective spaces; 5. Outline of quantum mechanics; 6. Coherent states and group actions; 7. The stellar representation; 8. The space of density matrices; 9. Purification of mixed quantum states; 10. Quantum operations; 11. Duality: maps versus states; 12. Density matrices and entropies; 13. Distinguishability measures; 14. Monotone metrics and measures; 15. Quantum entanglement; Epilogue; Appendices; References; Index.
Kus, M; Kus, Marek; Zyczkowski, Karol
2001-01-01
Geometric properties of the set of quantum entangled states are investigated. We propose an explicit method to compute the dimension of local orbits for any mixed state of the general K x M problem. In particular we analyze the simplest case of 2 x 2 problem finding a stratification of the 6-D set of N=4 pure states. The set of effectively different states (which cannot be related by local transformations) is one dimensional. It starts at a 3-D manifold of maximally entangled states, cuts generic 5-D manifolds of entangled states (labeled by non-zero values of the entropy of entanglement), and ends at a single 4-D manifold of separable states.
Whitfield, J D; Biamonte, J D
2012-01-01
Designing and optimizing cost functions and energy landscapes is a problem encountered in many fields of science and engineering. These landscapes and cost functions can be embedded and annealed in experimentally controllable spin Hamiltonians. Using an approach based on group theory and symmetries, we examine the embedding of Boolean logic gates into the ground state subspace of such spin systems. We describe parameterized families of diagonal Hamiltonians and symmetry operations which preserve the ground state subspace encoding the truth tables of Boolean formulas. The ground state embeddings of adder circuits are used to illustrate how gates are combined and simplified using symmetry. Our work is relevant for experimental demonstrations of ground state embeddings found in both classical optimization as well as adiabatic quantum optimization.
Singlet Ground State Magnetism:
DEFF Research Database (Denmark)
Loidl, A.; Knorr, K.; Kjems, Jørgen;
1979-01-01
The magneticGamma 1 –Gamma 4 exciton of the singlet ground state system TbP has been studied by inelastic neutron scattering above the antiferromagnetic ordering temperature. Considerable dispersion and a pronounced splitting was found in the [100] and [110] directions. Both the band width...... and the splitting increased rapidly as the transition temperature was approached in accordance with the predictions of the RPA-theory. The dispersion is analysed in terms of a phenomenological model using interactions up to the fourth nearest neighbour....
Ground state of a confined Yukawa plasma
Henning, C; Block, D; Bonitz, M; Golubnichiy, V; Ludwig, P; Piel, A
2006-01-01
The ground state of an externally confined one-component Yukawa plasma is derived analytically. In particular, the radial density profile is computed. The results agree very well with computer simulations on three-dimensional spherical Coulomb crystals. We conclude in presenting an exact equation for the density distribution for a confinement potential of arbitrary geometry.
Measuring finite quantum geometries via quasi-coherent states
Schneiderbauer, Lukas; Steinacker, Harold C.
2016-07-01
We develop a systematic approach to determine and measure numerically the geometry of generic quantum or ‘fuzzy’ geometries realized by a set of finite-dimensional Hermitian matrices. The method is designed to recover the semi-classical limit of quantized symplectic spaces embedded in {{{R}}}d including the well-known examples of fuzzy spaces, but it applies much more generally. The central tool is provided by quasi-coherent states, which are defined as ground states of Laplace- or Dirac operators corresponding to localized point branes in target space. The displacement energy of these quasi-coherent states is used to extract the local dimension and tangent space of the semi-classical geometry, and provides a measure for the quality and self-consistency of the semi-classical approximation. The method is discussed and tested with various examples, and implemented in an open-source Mathematica package.
Measuring finite Quantum Geometries via Quasi-Coherent States
Schneiderbauer, Lukas
2016-01-01
We develop a systematic approach to determine and measure numerically the geometry of generic quantum or "fuzzy" geometries realized by a set of finite-dimensional hermitian matrices. The method is designed to recover the semi-classical limit of quantized symplectic spaces embedded in $\\mathbb{R}^d$ including the well-known examples of fuzzy spaces, but it applies much more generally. The central tool is provided by quasi-coherent states, which are defined as ground states of Laplace- or Dirac operators corresponding to localized point branes in target space. The displacement energy of these quasi-coherent states is used to extract the local dimension and tangent space of the semi-classical geometry, and provides a measure for the quality and self-consistency of the semi-classical approximation. The method is discussed and tested with various examples, and implemented in an open-source Mathematica package.
The Bell states in noncommutative algebraic geometry
Beil, Charlie
2014-10-01
We introduce new mathematical aspects of the Bell states using matrix factorizations, non-noetherian singularities, and noncommutative blowups. A matrix factorization of a polynomial p consists of two matrices ϕ1, ϕ2 such that ϕ1ϕ2 = ϕ2ϕ1 = p id. Using this notion, we show how the Bell states emerge from the separable product of two mixtures, by defining pure states over complex matrices rather than just the complex numbers. We then show in an idealized algebraic setting that pure states are supported on non-noetherian singularities. Moreover, we find that the collapse of a Bell state is intimately related to the representation theory of the noncommutative blowup along its singular support. This presents an exchange in geometry: the nonlocal commutative spacetime of the entangled state emerges from an underlying local noncommutative spacetime.
Proximal Ignimbrite Geometry on Santorini, Greece Using Ground Penetrating Radar
Stasiuk, M. V.; Russell, J. K.; Hill, G. J.; Druitt, T. H.
2001-12-01
Ground penetrating radar (GPR) surveys on Santorini, Greece, are used to constrain the 3-dimensional geometry of the near-surface pyroclastic deposits produced by the 3.6 ka caldera-forming Minoan eruption. Specifically, the results elucidate deposit structures at the south end of the island. More than 2.4 km of radar survey data were collected at a measurement spacing of 0.5-1.0 m, using the common offset reflection method (3 m offset) and radar frequencies of 50 and 100 MHz. Imaging depths of the raw data were typically small (caldera rim while phase 4 gradually thickens. The GPR results suggest that the flows were more energetic than the previous model implied, and too energetic to bulk deposit in the subaerial, proximal area. Most of the mass of pyroclastics swept down the slope and into the sea, leaving behind only thin veneers. The velocity reduction caused by a combination of the phase 4 flow thickening as it passed over the ancient sea cliffs, and by entering the sea, caused the flow to switch to a strongly depositional mode resulting in a thickened deposit. An implication of these results is that most of the Minoan pyroclastic flow deposits on Santorini, apart from those near and on the outer coast, were emplaced aggradationally.
Numerical shadow and geometry of quantum states
Energy Technology Data Exchange (ETDEWEB)
Dunkl, Charles F [Department of Mathematics, University of Virginia, Charlottesville, VA 22904-4137 (United States); Gawron, Piotr; Miszczak, Jaroslaw A; Puchala, Zbigniew [Institute of Theoretical and Applied Informatics, Polish Academy of Sciences, Baltycka 5, 44-100 Gliwice (Poland); Holbrook, John A [Department of Mathematics and Statistics, University of Guelph, Guelph, Ontario N1G 2W1 (Canada); Zyczkowski, Karol, E-mail: cfd5z@virginia.edu, E-mail: gawron@iitis.pl, E-mail: jholbroo@uoguelph.ca, E-mail: miszczak@iitis.pl, E-mail: z.puchala@iitis.pl, E-mail: karol@tatry.if.uj.edu.pl [Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow (Poland)
2011-08-19
The totality of normalized density matrices of dimension N forms a convex set Q{sub N} in R{sup N2-1}. Working with the flat geometry induced by the Hilbert-Schmidt distance, we consider images of orthogonal projections of Q{sub N} onto a two-plane and show that they are similar to the numerical ranges of matrices of dimension N. For a matrix A of dimension N, one defines its numerical shadow as a probability distribution supported on its numerical range W(A), induced by the unitarily invariant Fubini-Study measure on the complex projective manifold CP{sup N-1}. We define generalized, mixed-state shadows of A and demonstrate their usefulness to analyse the structure of the set of quantum states and unitary dynamics therein.
Numerical shadow and geometry of quantum states
Dunkl, Charles F; Holbrook, John A; Miszczak, Jarosław A; Puchała, Zbigniew; Życzkowski, Karol
2011-01-01
The totality of normalised density matrices of order N forms a convex set Q_N in R^(N^2-1). Working with the flat geometry induced by the Hilbert-Schmidt distance we consider images of orthogonal projections of Q_N onto a two-plane and show that they are similar to the numerical ranges of matrices of order N. For a matrix A of a order N one defines its numerical shadow as a probability distribution supported on its numerical range W(A), induced by the unitarily invariant Fubini-Study measure on the complex projective manifold CP^(N-1). We define generalized, mixed-states shadows of A and demonstrate their usefulness to analyse the structure of the set of quantum states and unitary dynamics therein.
Pieper, Steven C.; Wiringa, R. B.; Pandharipande, V. R.
1990-01-01
A variational method is used to study the ground state of 16O. Expectation values are computed with a cluster expansion for the noncentral correlations in the wave function; the central correlations and exchanges are treated to all orders by Monte Carlo integration. The expansion has good convergence. Results are reported for the Argonne v14 two-nucleon and Urbana VII three-nucleon potentials.
Control wetting state transition by micro-rod geometry
He, Yang; Jiang, Chengyu; Wang, Shengkun; Yin, Hengxu; Yuan, Weizheng
2013-11-01
Understanding the effect of micro-structure geometry on wetting state transition is important to design and control surface wettability. Micro-rod model was proposed and the relationship between micro-rod geometry and wetting state was investigated in the paper taking into account only the surface roughness and neglecting the chemistry interaction. Micro-rods with different geometric parameters were fabricated using micro-fabrication technology. Their contact angles were measured and compared with theoretical ones. The experimental results indicated that increasing the height and decreasing the space of micro-rod may result in Cassie wetting state, while decreasing the height and increasing the space may result in Wenzel wetting state. A suspended wetting state model due to scallops was proposed. The wetting state transition was interpreted by intruding height, de-pinning and sag mechanism. It may offer a facile way to control the surface wetting state transition by changing the geometry of micro-rod.
Accurate Excited State Geometries within Reduced Subspace TDDFT/TDA.
Robinson, David
2014-12-09
A method for the calculation of TDDFT/TDA excited state geometries within a reduced subspace of Kohn-Sham orbitals has been implemented and tested. Accurate geometries are found for all of the fluorophore-like molecules tested, with at most all valence occupied orbitals and half of the virtual orbitals included but for some molecules even fewer orbitals. Efficiency gains of between 15 and 30% are found for essentially the same level of accuracy as a standard TDDFT/TDA excited state geometry optimization calculation.
Langevin equation path integral ground state.
Constable, Steve; Schmidt, Matthew; Ing, Christopher; Zeng, Tao; Roy, Pierre-Nicholas
2013-08-15
We propose a Langevin equation path integral ground state (LePIGS) approach for the calculation of ground state (zero temperature) properties of molecular systems. The approach is based on a modification of the finite temperature path integral Langevin equation (PILE) method (J. Chem. Phys. 2010, 133, 124104) to the case of open Feynman paths. Such open paths are necessary for a ground state formulation. We illustrate the applicability of the method using model systems and the weakly bound water-parahydrogen dimer. We show that the method can lead to converged zero point energies and structural properties.
On the ground state of metallic hydrogen
Chakravarty, S.; Ashcroft, N. W.
1978-01-01
A proposed liquid ground state of metallic hydrogen at zero temperature is explored and a variational upper bound to the ground state energy is calculated. The possibility that the metallic hydrogen is a liquid around the metastable point (rs = 1.64) cannot be ruled out. This conclusion crucially hinges on the contribution to the energy arising from the third order in the electron-proton interaction which is shown here to be more significant in the liquid phase than in crystals.
A global approach to ground state solutions
Directory of Open Access Journals (Sweden)
Philip Korman
2008-08-01
Full Text Available We study radial solutions of semilinear Laplace equations. We try to understand all solutions of the problem, regardless of the boundary behavior. It turns out that one can study uniqueness or multiplicity properties of ground state solutions by considering curves of solutions of the corresponding Dirichlet and Neumann problems. We show that uniqueness of ground state solutions can sometimes be approached by a numerical computation.
A global approach to ground state solutions
2008-01-01
We study radial solutions of semilinear Laplace equations. We try to understand all solutions of the problem, regardless of the boundary behavior. It turns out that one can study uniqueness or multiplicity properties of ground state solutions by considering curves of solutions of the corresponding Dirichlet and Neumann problems. We show that uniqueness of ground state solutions can sometimes be approached by a numerical computation.
Monge Metric on the Sphere and Geometry of Quantum States
Zyczkowski, K; Zyczkowski, Karol; Slomczynski, Wojciech
2001-01-01
Topological and geometrical properties of the set of mixed quantum states in the N-dimensional Hilbert space are analysed. Assuming that the corresponding classical dynamics takes place on the sphere we use the vector SU(2) coherent states to define the Monge distance between two arbitrary density matrices. The Monge metric has a simple semiclassical interpretation and induce$ a non-trivial geometry. Among all pure states the distance from the maximally mixed state \\rho_*, proportional to the identity matrix, admits the largest value for the coherent states, while the delocalized 'chaotic' states are close to \\rho_*. This contrasts the geometry induced by the standard (trace, Hilbert-Schmidt or Bures) metrics, for which the distance from \\rho_* is the same for all pure states. We discuss possible physical consequences including unitary time evolution and the process of decoherence.
Monge Metric on the Sphere and Geometry of Quantum States
Zyczkowski, Karol; Slomczynski, Wojciech
2000-01-01
Topological and geometrical properties of the set of mixed quantum states in the N-dimensional Hilbert space are analysed. Assuming that the corresponding classical dynamics takes place on the sphere we use the vector SU(2) coherent states and the generalised Husimi distributions to define the Monge distance between arbitrary two density matrices. The Monge metric has a simple semiclassical interpretation and induces a non-trivial geometry. Among all pure states the distance from the maximall...
Ground states for nonuniform periodic Ising chains
Martínez-Garcilazo, J. P.; Ramírez, C.
2015-04-01
We generalize Morita's works [J. Phys. A 7, 289 (1974), 10.1088/0305-4470/7/2/014; J. Phys. A 7, 1613 (1974), 10.1088/0305-4470/7/13/015] on ground states of Ising chains, for chains with a periodic structure and different spins, to any interaction order. The main assumption is translational invariance. The length of the irreducible blocks is a multiple of the period of the chain. If there is parity invariance, it restricts the length in general only in the diatomic case. There are degenerated states and under certain circumstances there could be nonregular ground states. We illustrate the results and give the ground state diagrams in several cases.
Geometry of quantum Hall states: Gravitational anomaly and transport coefficients
Energy Technology Data Exchange (ETDEWEB)
Can, Tankut, E-mail: tcan@scgp.stonybrook.edu [Simons Center for Geometry and Physics, Stony Brook University, Stony Brook, NY 11794 (United States); Laskin, Michael; Wiegmann, Paul B. [Department of Physics, University of Chicago, 929 57th St, Chicago, IL 60637 (United States)
2015-11-15
We show that universal transport coefficients of the fractional quantum Hall effect (FQHE) can be understood as a response to variations of spatial geometry. Some transport properties are essentially governed by the gravitational anomaly. We develop a general method to compute correlation functions of FQH states in a curved space, where local transformation properties of these states are examined through local geometric variations. We introduce the notion of a generating functional and relate it to geometric invariant functionals recently studied in geometry. We develop two complementary methods to study the geometry of the FQHE. One method is based on iterating a Ward identity, while the other is based on a field theoretical formulation of the FQHE through a path integral formalism.
Emergent geometry, thermal CFT and surface/state correspondence
Gan, Wen-Cong; Shu, Fu-Wen; Wu, Meng-He
2017-09-01
We study a conjectured correspondence between any codimension-two convex surface and a quantum state (SS-duality for short). By applying thermofield double formalism to the SS-duality, we show that thermal geometries naturally emerge as a result of hidden quantum entanglement between two boundary CFTs. We therefore propose a general framework to emerge the thermal geometry from CFT at finite temperature, without knowing many details about the thermal CFT. As an example, the case of 2d CFT is considered. We calculate its information metric and show that it is either BTZ black hole or thermal AdS as expected.
Ground states of linearly coupled Schrodinger systems
Directory of Open Access Journals (Sweden)
Haidong Liu
2017-01-01
Full Text Available This article concerns the standing waves of a linearly coupled Schrodinger system which arises from nonlinear optics and condensed matter physics. The coefficients of the system are spatially dependent and have a mixed behavior: they are periodic in some directions and tend to positive constants in other directions. Under suitable assumptions, we prove that the system has a positive ground state. In addition, when the L-infinity-norm of the coupling coefficient tends to zero, the asymptotic behavior of the ground states is also obtained.
Trapped Antihydrogen in Its Ground State
Gabrielse, G; Kolthammer, W S; McConnell, R; Richerme, P; Grzonka, D; Oelert, W; Sefzick, T; Zielinski, M; Fitzakerley, D W; George, M C; Hessels, E A; Storry, C H; Weel, M; Mullers, A; Walz, J
2012-01-01
Antihydrogen atoms are confined in an Ioffe trap for 15 to 1000 seconds -- long enough to ensure that they reach their ground state. Though reproducibility challenges remain in making large numbers of cold antiprotons and positrons interact, 5 +/- 1 simultaneously-confined ground state atoms are produced and observed on average, substantially more than previously reported. Increases in the number of simultaneously trapped antithydrogen atoms H are critical if laser-cooling of trapped antihydrogen is to be demonstrated, and spectroscopic studies at interesting levels of precision are to be carried out.
Potential Energy Surfaces of Nitrogen Dioxide for the Ground State
Institute of Scientific and Technical Information of China (English)
SHAO Ju-Xiang; ZHU Zheng-He; CHENG Xin-Lu; YANG Xiang-Dong
2007-01-01
The potential energy function of nitrogen dioxide with the C2v symmetry in the ground state is represented using the simplified Sorbie-Murrell many-body expansion function in terms of the symmetry of NO2. Using the potential energy function, some potential energy surfaces of NO2(C2v, X2A1), such as the bond stretching contour plot for a fixed equilibrium geometry angle θ and contour for O moving around N-O (R1), in which R1 is fixed at the equilibrium bond length, are depicted. The potential energy surfaces are analysed. Moreover, the equilibrium parameters for NO2 with the C2v, Cs and D8h symmetries, such as equilibrium geometry structures and energies, are calculated by the ab initio (CBS-Q) method.
Geometry of n-state systems, pure and mixed
Energy Technology Data Exchange (ETDEWEB)
Byrd, M S [Physics Department, Southern Illinois University, Carbondale, Illinois 62901-4401 (United States); Boya, L J [Departamento de Fiica Teorica, Facultad de Ciencias, Univeridad de Zaragoza. 50009 Zaragoza (Spain); Mims, M [Center for Particle Physics, Univesity of Texas at Austin, Austin, TX 787121081 (United States); Sudarshan, E C G [Center for Particle Physics, Univesity of Texas at Austin, Austin, TX 787121081 (United States)
2007-11-15
We discuss the geometry of states of quantum systems in an n-dimensional Hilbert space in terms of an explicit parameterization of all such systems. The geometry of the space of pure as well as mixed states for n-state systems is discussed. The parameterization is particularly useful since it allows for the simple construction and isolation of various physically meaningful subspaces of the space of all density matrices. This is used to describe possible geometric phases, their calculation, and analyze entropy and purity (or linear entropy) functions. In particular we provide conditions under which nontrivial abelian and/or nonabelian geometric phases aris in these subspaces in terms of the given parameterization, an explicit example is given, and multidimensional ientopic surfaces are discused.
Rearrangements in ground and excited states
de Mayo, Paul
1980-01-01
Rearrangements in Ground and Excited States, Volume 3 presents essays on the chemical generation of excited states; the cis-trans isomerization of olefins; and the photochemical rearrangements in trienes. The book also includes essays on the zimmerman rearrangements; the photochemical rearrangements of enones; the photochemical rearrangements of conjugated cyclic dienones; and the rearrangements of the benzene ring. Essays on the photo rearrangements via biradicals of simple carbonyl compounds; the photochemical rearrangements involving three-membered rings or five-membered ring heterocycles;
Pedoe, Dan
1988-01-01
""A lucid and masterly survey."" - Mathematics Gazette Professor Pedoe is widely known as a fine teacher and a fine geometer. His abilities in both areas are clearly evident in this self-contained, well-written, and lucid introduction to the scope and methods of elementary geometry. It covers the geometry usually included in undergraduate courses in mathematics, except for the theory of convex sets. Based on a course given by the author for several years at the University of Minnesota, the main purpose of the book is to increase geometrical, and therefore mathematical, understanding and to he
Trapping cold ground state argon atoms.
Edmunds, P D; Barker, P F
2014-10-31
We trap cold, ground state argon atoms in a deep optical dipole trap produced by a buildup cavity. The atoms, which are a general source for the sympathetic cooling of molecules, are loaded in the trap by quenching them from a cloud of laser-cooled metastable argon atoms. Although the ground state atoms cannot be directly probed, we detect them by observing the collisional loss of cotrapped metastable argon atoms and determine an elastic cross section. Using a type of parametric loss spectroscopy we also determine the polarizability of the metastable 4s[3/2](2) state to be (7.3±1.1)×10(-39) C m(2)/V. Finally, Penning and associative losses of metastable atoms in the absence of light assisted collisions, are determined to be (3.3±0.8)×10(-10) cm(3) s(-1).
Quantum typicality in spin network states of quantum geometry
Anzà, Fabio
2016-01-01
In this letter we extend the so-called typicality approach, originally formulated in statistical mechanics contexts, to SU(2) invariant spin network states. Our results do not depend on the physical interpretation of the spin-network, however they are mainly motivated by the fact that spin-network states can describe states of quantum geometry, providing a gauge-invariant basis for the kinematical Hilbert space of several background independent approaches to quantum gravity. The first result is, by itself, the existence of a regime in which we show the emergence of a typical state. We interpret this as the prove that, in that regime there are certain (local) properties of quantum geometry which are "universal". Such set of properties is heralded by the typical state, of which we give the explicit form. This is our second result. In the end, we study some interesting properties of the typical state, proving that the area-law for the entropy of a surface must be satisfied at the local level, up to logarithmic c...
Electronic Ground State of Higher Acenes
Jiang, De-en
2007-01-01
We examine the electronic ground state of acenes with different number of fused benzene rings (up to 40) by using first principles density functional theory. Their properties are compared with those of infinite polyacene. We find that the ground state of acenes that consist of more than seven fused benzene rings is an antiferromagnetic (in other words, open-shell singlet) state, and we show that this singlet is not necessarily a diradical, because the spatially separated magnetizations for the spin-up and spin-down electrons increase with the size of the acene. For example, our results indicate that there are about four spin-up electrons localized at one zigzag edge of 20-acene. The reason that both acenes and polyacene have the antiferromagnetic ground state is due to the zigzag-shaped boundaries, which cause pi-electrons to localize and form spin orders at the edges. Both wider graphene ribbons and large rectangular-shaped polycyclic aromatic hydrocarbons have been shown to share this antiferromagnetic grou...
Magnetic properties of ground-state mesons
Energy Technology Data Exchange (ETDEWEB)
Simonis, V. [Vilnius University Institute of Theoretical Physics and Astronomy, Vilnius (Lithuania)
2016-04-15
Starting with the bag model a method for the study of the magnetic properties (magnetic moments, magnetic dipole transition widths) of ground-state mesons is developed. We calculate the M1 transition moments and use them subsequently to estimate the corresponding decay widths. These are compared with experimental data, where available, and with the results obtained in other approaches. Finally, we give the predictions for the static magnetic moments of all ground-state vector mesons including those containing heavy quarks. We have a good agreement with experimental data for the M1 decay rates of light as well as heavy mesons. Therefore, we expect our predictions for the static magnetic properties (i.e., usual magnetic moments) to be of sufficiently high quality, too. (orig.)
First observation of $^{13}$Li ground state
Kohley, Z; DeYoung, P A; Volya, A; Baumann, T; Bazin, D; Christian, G; Cooper, N L; Frank, N; Gade, A; Hall, C; Hinnefeld, J; Luther, B; Mosby, S; Peters, W A; Smith, J K; Snyder, J; Spyrou, A; Thoennessen, M
2013-01-01
The ground state of neutron-rich unbound $^{13}$Li was observed for the first time in a one-proton removal reaction from $^{14}$Be at a beam energy of 53.6 MeV/u. The $^{13}$Li ground state was reconstructed from $^{11}$Li and two neutrons giving a resonance energy of 120$^{+60}_{-80}$ keV. All events involving single and double neutron interactions in the Modular Neutron Array (MoNA) were analyzed, simulated, and fitted self-consistently. The three-body ($^{11}$Li+$n+n$) correlations within Jacobi coordinates showed strong dineutron characteristics. The decay energy spectrum of the intermediate $^{12}$Li system ($^{11}$Li+$n$) was described with an s-wave scattering length of greater than -4 fm, which is a smaller absolute value than reported in a previous measurement.
Magnetic properties of ground-state mesons
Simonis, Vytautas
2016-01-01
Starting with the bag model a method for the study of the magnetic properties (magnetic moments, magnetic dipole transition widths) of ground-state mesons is developed. We calculate the M1 transition moments and use them subsequently to estimate the corresponding decay widths. These are compared with experimental data, where available, and with the results obtained in other approaches. Finally, we give the predictions for the static magnetic moments of all ground-state vector mesons including those containing heavy quarks. We have a good agreement with experimental data for the M1 decay rates of light as well as heavy mesons. Therefore, we expect our predictions for the static magnetic properties (usual magnetic moments) to be of sufficiently high quality, too.
Thermal ground state and nonthermal probes
Grandou, Thierry
2015-01-01
The Euclidean formulation of SU(2) Yang-Mills thermodynamics admits periodic, (anti)selfdual solutions to the fundamental, classical equation of motion which possess one unit of topological charge: (anti)calorons. A spatial coarse graining over the central region in a pair of such localised field configurations with trivial holonomy generates an inert adjoint scalar field $\\phi$, effectively describing the pure quantum part of the thermal ground state in the induced quantum field theory. The latter's local vertices are mediated by just-not-resolved (anti)caloron centers of action $\\hbar$. This is the basic reason for a rapid convergence of the loop expansion of thermodynamical quantities, polarization tensors, etc., their effective loop momenta being severely constrained in entirely fixed and physical unitary-Coulomb gauge. Here we show for the limit of zero holonomy how (anti)calorons associate a temperature independent electric permittivity and magnetic permeability to the thermal ground state of SU(2)$_{\\t...
Electronic ground state of Ni$_2^+$
Zamudio-Bayer, V; Bülow, C; Leistner, G; Terasaki, A; Issendorff, B v; Lau, J T
2016-01-01
The $^{4}\\Phi_{9/2}$ ground state of the Ni$_2^+$ diatomic molecular cation is determined experimentally from temperature and magnetic-field-dependent x-ray magnetic circular dichroism spectroscopy in a cryogenic ion trap, where an electronic and rotational temperature of $7.4 \\pm 0.2$ K was achieved by buffer gas cooling of the molecular ion. The contribution of the magnetic dipole term to the x-ray magnetic circular dichroism spin sum rule amounts to $7\\, T_z = 0.17 \\pm 0.06$ $\\mu_B$ per atom, approximately 11 \\% of the spin magnetic moment. We find that, in general, homonuclear diatomic molecular cations of $3d$ transition metals seem to adopt maximum spin magnetic moments in their electronic ground states.
Strangeness in the baryon ground states
Semke, A
2012-01-01
We compute the strangeness content of the baryon ground states based on an analysis of recent lattice simulations of the BMW, PACS, LHPC and HSC groups for the pion-mass dependence of the baryon masses. Our results rely on the relativistic chiral Lagrangian and large-$N_c$ sum rule estimates of the counter terms relevant for the baryon masses at N$^3$LO. A partial summation is implied by the use of physical baryon and meson masses in the one-loop contributions to the baryon self energies. A simultaneous description of the lattice results of the BMW, LHPC, PACS and HSC groups is achieved. We predict the pion- and strangeness sigma terms and the pion-mass dependence of the octet and decuplet ground states at different strange quark masses.
From 3-geometry transition amplitudes to graviton states
Mattei, F; Speziale, S; Testa, M; Mattei, Federico; Rovelli, Carlo; Speziale, Simone; Testa, Massimo
2006-01-01
In various background independent approaches, quantum gravity is defined in terms of a field propagation kernel: a sum over paths interpreted as a transition amplitude between 3-geometries, expected to project quantum states of the geometry on the solutions of the Wheeler-DeWitt equation. We study the relation between this formalism and conventional quantum field theory methods. We consider the propagation kernel of 4d Lorentzian general relativity in the temporal gauge, defined by a conventional formal Feynman path integral, gauge fixed a' la Fadeev--Popov. If space is compact, this turns out to depend only on the initial and final 3--geometries, while in the asymptotically flat case it depends also on the asymptotic proper time. We compute the explicit form of this kernel at first order around flat space, and show that it projects on the solutions of all quantum constraints, including the Wheeler-DeWitt equation, and yields the correct vacuum and n-graviton states. We also illustrate how the Newtonian inter...
From 3-geometry transition amplitudes to graviton states
Mattei, Federico; Rovelli, Carlo; Speziale, Simone; Testa, Massimo
2006-04-01
In various background independent approaches, quantum gravity is defined in terms of a field propagation kernel: a sum over paths interpreted as a transition amplitude between 3-geometries, expected to project quantum states of the geometry on the solutions of the Wheeler-deWitt equation. We study the relation between this formalism and conventional quantum field theory methods. We consider the propagation kernel of 4d Lorentzian general relativity in the temporal gauge, defined by a conventional formal Feynman path integral, gauge fixed à la Faddeev-Popov. If space is compact, this turns out to depend only on the initial and final 3-geometries, while in the asymptotically flat case it depends also on the asymptotic proper time. We compute the explicit form of this kernel at first order around flat space, and show that it projects on the solutions of all quantum constraints, including the Wheeler-DeWitt equation, and yields the correct vacuum and n-graviton states. We also illustrate how the Newtonian interaction is coded into the propagation kernel, a key open issue in the spinfoam approach.
Rearrangements in ground and excited states
de Mayo, Paul
1980-01-01
Rearrangements in Ground and Excited States, Volume 2 covers essays on the theoretical approach of rearrangements; the rearrangements involving boron; and the molecular rearrangements of organosilicon compounds. The book also includes essays on the polytopal rearrangement at phosphorus; the rearrangement in coordination complexes; and the reversible thermal intramolecular rearrangements of metal carbonyls. Chemists and people involved in the study of rearrangements will find the book invaluable.
Ground states for the fractional Schrodinger equation
Directory of Open Access Journals (Sweden)
Binhua Feng
2013-05-01
Full Text Available In this article, we show the existence of ground state solutions for the nonlinear Schrodinger equation with fractional Laplacian $$ (-Delta ^alpha u+ V(xu =lambda |u|^{p}uquadhbox{in $mathbb{R}^N$ for $alpha in (0,1$}. $$ We use the concentration compactness principle in fractional Sobolev spaces $H^alpha$ for $alpha in (0,1$. Our results generalize the corresponding results in the case $alpha =1$.
Repellin, Cécile; Neupert, Titus; Bernevig, B. Andrei; Regnault, Nicolas
2015-09-01
Multilayer fractional quantum Hall wave functions can be used to construct the non-Abelian states of the Zk Read-Rezayi series upon symmetrization over the layer index. Unfortunately, this construction does not yield the complete set of Zk ground states on the torus. We develop an alternative projective construction of Zk Read-Rezayi states that complements the existing one. On the multilayer torus geometry, our construction consists of introducing twisted boundary conditions connecting the layers before performing the symmetrization. We give a comprehensive account of this construction for bosonic states, and numerically show that the full ground state and quasihole manifolds are recovered for all computationally accessible system sizes. Furthermore, we analyze the neutral excitation modes above the Moore-Read on the torus through an extensive exact diagonalization study. We show numerically that our construction can be used to obtain excellent approximations to these modes. Finally, we extend our symmetrization scheme to the plane and sphere geometries.
Emergent geometry, thermal CFT and surface/state correspondence
Gan, Wen-Cong; Wu, Meng-He
2016-01-01
We study a conjectured correspondence between any codimension two convex surface and a quantum state (SS-duality for short). By generalizing thermofield double formalism to continuum version of the multi-scale entanglement renormalization ansatz (cMERA) and using the SS-duality, we propose a general framework to emerge the thermal geometry from CFT at finite temperature. As an example, the case of $2d$ CFT is considered carefully. We calculate its information metric and show that it is the BTZ black hole or the thermal AdS as expectation.
The polaron: Ground state, excited states, and far from equilibrium
Energy Technology Data Exchange (ETDEWEB)
Trugman, S.A. [Los Alamos National Lab., NM (United States). Theory Div.; Bonca, J. [Univ. of Ljubljana (Slovenia)]|[Jozef Stefan Inst., Ljubljana (Slovenia)
1998-12-01
The authors describe a variational approach for solving the Holstein polaron model with dynamical quantum phonons on an infinite lattice. The method is simple, fast, extremely accurate, and gives ground and excited state energies and wavefunctions at any momentum k. The method can also be used to calculate coherent quantum dynamics for inelastic tunneling and for strongly driven polarons far from equilibrium.
Characterizing Englacial Attenuation and Grounding Zone Geometry Using Airborne Radar Sounding
Schroeder, D. M.; Grima, C.; Blankenship, D. D.
2014-12-01
The impact of warm ocean water on ice sheet retreat and stability is a one of the primary drivers and sources of uncertainty for the rate of global sea level rise. One critical but challenging observation required to understand and model this impact is the location and extent of grounding ice sheet zones. However, existing surface topography based techniques do not directly detect the location where ocean water reaches (or breaches) grounded ice at the bed, which can significantly affect ice sheet stability. The primary geophysical tool for directly observing the basal properties of ice sheets is airborne radar sounding. However, uncertainty in englacial attenuation from unknown ice temperature and chemistry can lead to erroneous interpretation of subglacial conditions from bed echo strengths alone . Recently developed analysis techniques for radar sounding data have overcome this challenge by taking advantage of information in the angular distribution of bed echo energy and joint modeling of radar returns and water routing. We have developed similar approaches to analyze the spatial pattern and character of echoes to address the problems of improved characterization of grounding zone geometry and englacial attenuation. The spatial signal of the transition from an ice-bed interface to an ice-ocean interface is an increase in bed echo strength. However, rapidly changing attenuation near the grounding zone prevents the unambiguous interpretation of this signal in typical echo strength profiles and violates the assumptions of existing empirical attenuation correction techniques. We present a technique that treat bed echoes as continuous signals to take advantage of along-profile ice thickness and echo strength variations to constrain the spatial pattern of attenuation and detect the grounding zone transition. The transition from an ice-bed interface to an ice-ocean interface will also result in a change in the processes that determine basal interface morphology (e
Thermodynamic Ground States of Complex Oxide Heterointerfaces
DEFF Research Database (Denmark)
Gunkel, F.; Hoffmann-Eifert, S.; Heinen, R. A.
2017-01-01
The formation mechanism of 2-dimensional electron gases (2DEGs) at heterointerfaces between nominally insulating oxides is addressed with a thermodynamical approach. We provide a comprehensive analysis of the thermodynamic ground states of various 2DEG systems directly probed in high temperature...... equilibrium conductivity measurements. We unambiguously identify two distinct classes of oxide heterostructures: For epitaxial perovskite/perovskite heterointerfaces (LaAlO3/SrTiO3, NdGaO3/SrTiO3, and (La,Sr)(Al,Ta)O3/SrTiO3), we find the 2DEG formation being based on charge transfer into the interface...
Superimposed particles in 1D ground states
Energy Technology Data Exchange (ETDEWEB)
Sueto, Andras, E-mail: suto@szfki.hu [Research Institute for Solid State Physics and Optics, Hungarian Academy of Sciences, PO Box 49, H-1525 Budapest (Hungary)
2011-01-21
For a class of nonnegative, range-1 pair potentials in one-dimensional continuous space we prove that any classical ground state of lower density {>=}1 is a tower-lattice, i.e. a lattice formed by towers of particles the heights of which can differ only by 1, and the lattice constant is 1. The potential may be flat or may have a cusp at the origin; it can be continuous, but its derivative has a jump at 1. The result is valid on finite intervals or rings of integer length and on the whole line.
Shukla, M K; Leszczynski, Jerzy
2005-09-15
An ab-initio computational study was performed to investigate the effect of explicit hydration on the ground and lowest singlet PiPi* excited-state geometry and on the selected stretching vibrational frequencies corresponding to the different NH sites of the guanine acting as hydrogen-bond donors. The studied systems consisted of guanine interacting with one, three, five, six, and seven water molecules. Ground-state geometries were optimized at the HF level, while excited-state geometries were optimized at the CIS level. The 6-311G(d,p) basis set was used in all calculations. The nature of potential energy surfaces was ascertained via the harmonic vibrational frequency analysis; all structures were found minima at the respective potential energy surfaces. The changes in the geometry and the stretching vibrational frequencies of hydrogen-bond-donating sites of the guanine in the ground and excited state consequent to the hydration are discussed. It was found that the first solvation shell of the guanine can accommodate up to six water molecules. The addition of the another water molecule distorts the hydrogen-bonding network by displacing other neighboring water molecules away from the guanine plane.
Ground-state structures of Hafnium clusters
Energy Technology Data Exchange (ETDEWEB)
Ng, Wei Chun; Yoon, Tiem Leong [School of Physics, Universiti Sains Malaysia, 11800 USM, Penang (Malaysia); Lim, Thong Leng [Faculty of Engineering and Technoloty, Multimedia University, Melaca Campus, 75450 Melaka (Malaysia)
2015-04-24
Hafnium (Hf) is a very large tetra-valence d-block element which is able to form relatively long covalent bond. Researchers are interested to search for substitution to silicon in the semi-conductor industry. We attempt to obtain the ground-state structures of small Hf clusters at both empirical and density-functional theory (DFT) levels. For calculations at the empirical level, charge-optimized many-body functional potential (COMB) is used. The lowest-energy structures are obtained via a novel global-minimum search algorithm known as parallel tempering Monte-Carlo Basin-Hopping and Genetic Algorithm (PTMBHGA). The virtue of using COMB potential for Hf cluster calculation lies in the fact that by including the charge optimization at the valence shells, we can encourage the formation of proper bond hybridization, and thus getting the correct bond order. The obtained structures are further optimized using DFT to ensure a close proximity to the ground-state.
New ground state for quantum gravity
Magueijo, Joao
2012-01-01
In this paper we conjecture the existence of a new "ground" state in quantum gravity, supplying a wave function for the inflationary Universe. We present its explicit perturbative expression in the connection representation, exhibiting the associated inner product. The state is chiral, dependent on the Immirzi parameter, and is the vacuum of a second quantized theory of graviton particles. We identify the physical and unphysical Hilbert sub-spaces. We then contrast this state with the perturbed Kodama state and explain why the latter can never describe gravitons in a de Sitter background. Instead, it describes self-dual excitations, which are composites of the positive frequencies of the right-handed graviton and the negative frequencies of the left-handed graviton. These excitations are shown to be unphysical under the inner product we have identified. Our rejection of the Kodama state has a moral tale to it: the semi-classical limit of quantum gravity can be the wrong path for making contact with reality (w...
Ground and Excited States Of OH(-)(H2O)n Clusters.
Zanuttini, David; Gervais, Benoit
2015-07-23
We present an ab initio study of OH(-)(H2O)n (n = 1-7) clusters in their lowest three singlet and two triplet electronic states, calculated with the RASPT2 method. Minimum energy structures were obtained by geometry optimization for both (a) the 1(1)Σ(+) ground state and (b) the 1(3)Π excited state. From these structures, vertical detachment energies (VDEs), transition energies, and atomic charges were calculated. (a) We found that ground-state geometries present the hydroxide at the surface, accepting three and four H bonds from water. The excess charge is strongly stabilized by water up to a VDE of 6.7 eV for n = 7. Bound singlet excited states for ground-state geometries exist for n ≥ 3, and their VDE increases up to 1 eV for n = 7. (b) The 1(3)Π state equilibrium geometries completely differ from the ground-state geometries. They are characterized by the hydroxide acting as a single H bond donor to a water molecule, which then donates a H-bond to two others, forming a "tree" pattern. All minimum energy structures present this "tree" pattern and a constant total number of 2n - 2 H bonds, or equivalently 3 dangling hydrogens. The excess charge stabilizes from n = 2 and goes mainly at the surface, on the dangling hydrogens of water. An almost neutral OH radical is then formed. Resulting structural resemblances with the neutral system make the VDEs of the first excited states weakly geometry dependent but size sensitive because of additive polarization effects. In contrast, the 1(1)Σ(+) state at the 1(3)Π geometries is strongly sensitive to structural patterns. We bring out existing correlations between these patterns and the corresponding 1(1)Σ(+) state energy increase, which leads to couplings with excited states and possibly to an inversion of the state energy order. From these assessments, we propose a scenario for recombination of aqueous hydroxide following excitation in a charge-transfer-to-solvent state.
Ground state of high-density matter
Copeland, ED; Kolb, Edward W.; Lee, Kimyeong
1988-01-01
It is shown that if an upper bound to the false vacuum energy of the electroweak Higgs potential is satisfied, the true ground state of high-density matter is not nuclear matter, or even strange-quark matter, but rather a non-topological soliton where the electroweak symmetry is exact and the fermions are massless. This possibility is examined in the standard SU(3) sub C tensor product SU(2) sub L tensor product U(1) sub Y model. The bound to the false vacuum energy is satisfied only for a narrow range of the Higgs boson masses in the minimal electroweak model (within about 10 eV of its minimum allowed value of 6.6 GeV) and a somewhat wider range for electroweak models with a non-minimal Higgs sector.
Ground State Properties of Neutron Magic Nuclei
Saxena, G
2016-01-01
A systematic study of the ground state properties of the entire chains of even even neutron magic nuclei represented by isotones of traditional neutron magic numbers N = 8, 20, 40, 50, 82 and 126 has been carried out using relativistic mean field (rmf) plus Bardeen Cooper Schrieffer (BCS) approach. Our present investigation includes deformation, binding energy, two proton separation energy, single particle energy, rms radii along with proton and neutron density profiles, etc. Several of these results are compared with the results calculated using non relativistic approach (Skyrme Hartree Fock method) along with available experimental data and indeed they are found with excellent agreement. In addition, the possible locations of the proton and neutron drip lines, the (Z,N) values for the new shell closures, disappearance of traditional shell closures as suggested by the detailed analyzes of results are also discussed in detail.
Thermodynamic ground states of platinum metal nitrides
Energy Technology Data Exchange (ETDEWEB)
Aberg, D; Sadigh, B; Crowhurst, J; Goncharov, A
2007-10-09
We have systematically studied the thermodynamic stabilities of various phases of the nitrides of the platinum metal elements using density functional theory. We show that for the nitrides of Rh, Pd, Ir and Pt two new crystal structures, in which the metal ions occupy simple tetragonal lattice sites, have lower formation enthalpies at ambient conditions than any previously proposed structures. The region of stability can extend up to 17 GPa for PtN{sub 2}. Furthermore, we show that according to calculations using the local density approximation, these new compounds are also thermodynamically stable at ambient pressure and thus may be the ground state phases for these materials. We further discuss the fact that the local density and generalized gradient approximations predict different values of the absolute formation enthalpies as well different relative stabilities between simple tetragonal and the pyrite or marcasite structures.
Fingerprints of Majorana Bound States in Aharonov-Bohm Geometry
Tripathi, Krashna Mohan; Das, Sourin; Rao, Sumathi
2016-04-01
We study a ring geometry, coupled to two normal metallic leads, which has a Majorana bound state (MBS) embedded in one of its arms and is threaded by Aharonov-Bohm (A B ) flux ϕ . We show that by varying the A B flux, the two leads go through resonance in an anticorrelated fashion while the resonance conductance is quantized to 2 e2/h . We further show that such anticorrelation is completely absent when the MBS is replaced by an Andreev bound state (ABS). Hence this anti-correlation in conductance when studied as a function of ϕ provides a unique signature of the MBS which cannot be faked by an ABS. We contrast the phase sensitivity of the MBS and ABS in terms of tunneling conductances. We argue that the relative phase between the tunneling amplitude of the electrons and holes from either lead to the level (MBS or ABS), which is constrained to 0 ,π for the MBS and unconstrained for the ABS, is responsible for this interesting contrast in the A B effect between the MBS and ABS.
Powell, Rocky O.; Miller, Sarah J.; Westergard, Britt E.; Mulvihill, Christiane I.; Baldigo, Barry P.; Gallagher, Anne S.; Starr, Richard R.
2004-01-01
Many disturbed streams within New York State are being restored in an effort to provide bank and bed stability and thereby decrease sedimentation and erosion. Efforts to identify and provide accurate indicators for stable-channel characteristics for ungaged streams have been hampered by the lack of regional equations or relations that relate drainage area to bankfull discharge and to channel depth, width, and cross-sectional area (bankfull hydraulic-geometry relations). Regional equations are needed to confirm bankfull hydraulic-geometry, assess stream stability, evaluate restoration needs, and verify restoration design for ungaged streams that lack stage-to-discharge ratings or historic peak-flow records. This report presents guidelines for surveying bankfull channel geometry at USGS stream gages and developing regional hydraulic-geometry relations (equations) for wadeable streams in New York. It summarizes methods to (1) compile and assess existing hydrologic, geometric, photographic, and topographic data, (2) conduct stream-reconnaissance inspections, (3) identify channel-bankfull characteristics, (4) conduct longitudinal and cross-section surveys, (5) measure stream discharge, (6) develop and refine bankfull hydraulic-geometry equations, and (7) analyze and assure data completeness and quality. The techniques primarily address wadeable streams with either active or discontinued surface-water and crest-stage gages. The relations can be applied to ungaged or actively gaged streams that are wadeable, and may be extended to non-wadeable streams (with some limitations) if they have drainage areas comparable to those used to develop the relations.
Solving Quantum Ground-State Problems with Nuclear Magnetic Resonance
Li, Zhaokai; Chen, Hongwei; Lu, Dawei; Whitfield, James D; Peng, Xinhua; Aspuru-Guzik, Alán; Du, Jiangfeng
2011-01-01
Quantum ground-state problems are computationally hard problems; for general many-body Hamiltonians, there is no classical or quantum algorithm known to be able to solve them efficiently. Nevertheless, if a trial wavefunction approximating the ground state is available, as often happens for many problems in physics and chemistry, a quantum computer could employ this trial wavefunction to project the ground state by means of the phase estimation algorithm (PEA). We performed an experimental realization of this idea by implementing a variational-wavefunction approach to solve the ground-state problem of the Heisenberg spin model with an NMR quantum simulator. Our iterative phase estimation procedure yields a high accuracy for the eigenenergies (to the 10^-5 decimal digit). The ground-state fidelity was distilled to be more than 80%, and the singlet-to-triplet switching near the critical field is reliably captured. This result shows that quantum simulators can better leverage classical trial wavefunctions than c...
Institute of Scientific and Technical Information of China (English)
E.Javadimanesh; H.Hassanabadi; A.A.Rajabi; H.Rahimov; S.Zarrinkamar
2012-01-01
We study the half-lives of some nuclei via the alpha-decay process from ground state to ground state. To go through the problem, we have considered a potential model with Yukawa proximity potential and have thereby calculated the half-lives. The comparison with the existing data is motivating.
Structure and analytical potential energy function for the ground state of the BCx (x=0, -1)
Institute of Scientific and Technical Information of China (English)
Geng Zhen-Duo; Zhang Yan-Song; Fan Xiao-Wei; Lu Zhan-Sheng; Luo Gai-Xia
2006-01-01
In this paper, the electronic states of the ground states and dissociation limits of BC and BC- are correctly determined based on group theory and atomic and molecular reaction statics. The equilibrium geometries, harmonic frequencies and dissociation energies of the ground state of BC and BC- are calculated by using density function theory and quadratic CI method including single and double substitutions. The analytical potential energy functions of these states have been fitted with Murrell-Sorbie potential energy function from our ab initio calculation results. The spectroscopic data (αe, ωe and ωeXe) of each state is calculated via the relation between analytical potential energy function and spectroscopic data. All the calculations are in good agreement with the experimental data.
Geometry of non-supersymmetric three-charge bound states
Energy Technology Data Exchange (ETDEWEB)
Gimon, Eric; Gimon, Eric G.; Levi, Thomas S.; Ross, Simon F.
2007-05-14
We study the smooth non-supersymmetric three-charge microstatesof Jejjala, Madden, Ross and Titchener using Kaluza-Klein reductions of the solutions to five and four dimensions. Our aim is to improve our understanding of the relation between these non-supersymmetric solutions and the well-studied supersymmetric cases. We find some surprising qualitative differences. In the five-dimensional description, the solution has orbifold fixed points which break supersymmetry locally, so the geometries cannot be thought of as made up of separate half-BPS centers. In the four-dimensional description, the two singularities in the geometry are connected by a conical singularity, which makes it impossible to treat them independently and assign unambiguous brane charges to these centers.
Ground state correlations and mean field in 16O
Heisenberg, Jochen H.; Mihaila, Bogdan
1999-03-01
We use the coupled cluster expansion [exp(S) method] to generate the complete ground state correlations due to the NN interaction. Part of this procedure is the calculation of the two-body G matrix inside the nucleus in which it is being used. This formalism is being applied to 16O in a configuration space of 50ħω. The resulting ground state wave function is used to calculate the binding energy and one- and two-body densities for the ground state of 16O.
Ground state correlations and mean-field in $^{16}$O
Heisenberg, J H; Heisenberg, Jochen H.; Mihaila, Bogdan.
1999-01-01
We use the coupled cluster expansion ($\\exp(S)$ method) to generate the complete ground state correlations due to the $NN$ interaction. Part of this procedure is the calculation of the two-body ${\\mathbf G}$ matrix inside the nucleus in which it is being used. This formalism is being applied to $^{16}$O in a configuration space of 35 $\\hbar\\omega$. The resulting ground state wave function is used to calculate the binding energy and one- and two-body densities for the ground state of~$^{16}$O.
Classical ground states of symmetric Heisenberg spin systems
Schmidt, H J
2003-01-01
We investigate the ground states of classical Heisenberg spin systems which have point group symmetry. Examples are the regular polygons (spin rings) and the seven quasi-regular polyhedra including the five Platonic solids. For these examples, ground states with special properties, e.g. coplanarity or symmetry, can be completely enumerated using group-theoretical methods. For systems having coplanar (anti-) ground states with vanishing total spin we also calculate the smallest and largest energies of all states having a given total spin S. We find that these extremal energies depend quadratically on S and prove that, under certain assumptions, this happens only for systems with coplanar S = 0 ground states. For general systems the corresponding parabolas represent lower and upper bounds for the energy values. This provides strong support and clarifies the conditions for the so-called rotational band structure hypothesis which has been numerically established for many quantum spin systems.
Moment methods in extremal geometry
De Laat, D.
2016-01-01
In this thesis we develop techniques for solving problems in extremal geometry. We give an infinite dimensional generalization of moment techniques from polynomial optimization. We use this to construct semidefinite programming hierarchies for approximating optimal packing densities and ground state
Moment methods in extremal geometry
De Laat, D.
2016-01-01
In this thesis we develop techniques for solving problems in extremal geometry. We give an infinite dimensional generalization of moment techniques from polynomial optimization. We use this to construct semidefinite programming hierarchies for approximating optimal packing densities and ground state
Ground state energy of the modified Nambu-Goto string
Hadasz, L
1998-01-01
We calculate, using zeta function regularization method, semiclassical energy of the Nambu-Goto string supplemented with the boundary, Gauss-Bonnet term in the action and discuss the tachyonic ground state problem.
Arsenic in Ground Water of the United States - Direct Download
U.S. Geological Survey, Department of the Interior — This image shows national-scale patterns of naturally occurring arsenic in potable ground-water resources of the continental United States. The image was generated...
ON GROUND STATE SOLUTIONS FOR SUPERLINEAR DIRAC EQUATION
Institute of Scientific and Technical Information of China (English)
张建; 唐先华; 张文
2014-01-01
This article is concerned with the nonlinear Dirac equations Under suitable assumptions on the nonlinearity, we establish the existence of ground state solutions by the generalized Nehari manifold method developed recently by Szulkin and Weth.
Entanglement of two ground state neutral atoms using Rydberg blockade
DEFF Research Database (Denmark)
Miroshnychenko, Yevhen; Browaeys, Antoine; Evellin, Charles
2011-01-01
We report on our recent progress in trapping and manipulation of internal states of single neutral rubidium atoms in optical tweezers. We demonstrate the creation of an entangled state between two ground state atoms trapped in separate tweezers using the effect of Rydberg blockade. The quality of...
Borromean ground state of fermions in two dimensions
DEFF Research Database (Denmark)
G. Volosniev, A.; V. Fedorov, D.; S. Jensen, A.;
2014-01-01
-body threshold. They are the lowest in a possible sequence of so-called super-Efimov states. While the observation of the super-Efimov scaling could be very difficult, the borromean ground state should be observable in cold atomic gases and could be the basis for producing a quantum gas of three-body states...
Theory of ground state factorization in quantum cooperative systems.
Giampaolo, Salvatore M; Adesso, Gerardo; Illuminati, Fabrizio
2008-05-16
We introduce a general analytic approach to the study of factorization points and factorized ground states in quantum cooperative systems. The method allows us to determine rigorously the existence, location, and exact form of separable ground states in a large variety of, generally nonexactly solvable, spin models belonging to different universality classes. The theory applies to translationally invariant systems, irrespective of spatial dimensionality, and for spin-spin interactions of arbitrary range.
Quasiparticle Random Phase Approximation with an optimal Ground State
Simkovic, F; Raduta, A A
2001-01-01
A new Quasiparticle Random Phase Approximation approach is presented. The corresponding ground state is variationally determined and exhibits a minimum energy. New solutions for the ground state, some with spontaneously broken symmetry, of a solvable Hamiltonian are found. A non-iterative procedure to solve the non-linear QRPA equations is used and thus all possible solutions are found. These are compared with the exact results as well as with the solutions provided by other approaches.
Toward Triplet Ground State NaLi Molecules
Ebadi, Sepehr; Jamison, Alan; Rvachov, Timur; Jing, Li; Son, Hyungmok; Jiang, Yijun; Zwierlein, Martin; Ketterle, Wolfgang
2016-05-01
The NaLi molecule is expected to have a long lifetime in the triplet ground-state due to its fermionic nature, large rotational constant, and weak spin-orbit coupling. The triplet state has both electric and magnetic dipole moments, affording unique opportunities in quantum simulation and ultracold chemistry. We have mapped the excited state NaLi triplet potential by means of photoassociation spectroscopy. We report on this and our further progress toward the creation of the triplet ground-state molecules using STIRAP. NSF, ARO-MURI, Samsung, NSERC.
State-space Geometry, Statistical Fluctuations and Black Holes in String Theory
Bellucci, Stefano
2011-01-01
We study the state-space geometry of various extremal and nonextremal black holes in string theory. From the notion of the intrinsic geometry, we offer a new perspective of black hole vacuum fluctuations. For a given black hole entropy, we explicate the intrinsic state-space geometric meaning of the statistical fluctuations, local and global stability conditions and long range statistical correlations. We provide a set of physical motivations pertaining to the extremal and nonextremal black holes, \\textit{viz.}, the meaning of the chemical geometry and physics of correlation. We illustrate the state-space configurations for general charge extremal black holes. In sequel, we extend our analysis for various possible charge and anticharge nonextremal black holes. From the perspective of statistical fluctuation theory, we offer general remarks, future directions and open issues towards the intrinsic geometric understanding of the vacuum fluctuations and black holes in string theory. Keywords: Intrinsic Geometry; ...
Geometry and large N limits in Laughlin states
Klevtsov, Semyon
2016-01-01
In these notes I survey geometric aspects of the lowest Landau level wave functions, integer quantum Hall state and Laughlin states on compact Riemann surfaces. In particular, I review geometric adiabatic transport on the moduli spaces, derivation of the electromagnetic and gravitational anomalies, Chern-Simons theory and adiabatic phase, and the relation to holomorphic line bundles, Quillen metric, regularized spectral determinants, bosonisation formulas on Riemann surfaces and asymptotic expansion of the Bergman kernel.
Ensemble Theory for Stealthy Hyperuniform Disordered Ground States
Directory of Open Access Journals (Sweden)
S. Torquato
2015-05-01
Full Text Available It has been shown numerically that systems of particles interacting with isotropic “stealthy” bounded long-ranged pair potentials (similar to Friedel oscillations have classical ground states that are (counterintuitively disordered, hyperuniform, and highly degenerate. Disordered hyperuniform systems have received attention recently because they are distinguishable exotic states of matter poised between a crystal and liquid that are endowed with novel thermodynamic and physical properties. The task of formulating an ensemble theory that yields analytical predictions for the structural characteristics and other properties of stealthy degenerate ground states in d-dimensional Euclidean space R^{d} is highly nontrivial because the dimensionality of the configuration space depends on the number density ρ and there is a multitude of ways of sampling the ground-state manifold, each with its own probability measure for finding a particular ground-state configuration. The purpose of this paper is to take some initial steps in this direction. Specifically, we derive general exact relations for thermodynamic properties (energy, pressure, and isothermal compressibility that apply to any ground-state ensemble as a function of ρ in any d, and we show how disordered degenerate ground states arise as part of the ground-state manifold. We also derive exact integral conditions that both the pair correlation function g_{2}(r and structure factor S(k must obey for any d. We then specialize our results to the canonical ensemble (in the zero-temperature limit by exploiting an ansatz that stealthy states behave remarkably like “pseudo”-equilibrium hard-sphere systems in Fourier space. Our theoretical predictions for g_{2}(r and S(k are in excellent agreement with computer simulations across the first three space dimensions. These results are used to obtain order metrics, local number variance, and nearest-neighbor functions across dimensions. We also derive
Ensemble Theory for Stealthy Hyperuniform Disordered Ground States
Torquato, S.; Zhang, G.; Stillinger, F. H.
2015-04-01
It has been shown numerically that systems of particles interacting with isotropic "stealthy" bounded long-ranged pair potentials (similar to Friedel oscillations) have classical ground states that are (counterintuitively) disordered, hyperuniform, and highly degenerate. Disordered hyperuniform systems have received attention recently because they are distinguishable exotic states of matter poised between a crystal and liquid that are endowed with novel thermodynamic and physical properties. The task of formulating an ensemble theory that yields analytical predictions for the structural characteristics and other properties of stealthy degenerate ground states in d -dimensional Euclidean space Rd is highly nontrivial because the dimensionality of the configuration space depends on the number density ρ and there is a multitude of ways of sampling the ground-state manifold, each with its own probability measure for finding a particular ground-state configuration. The purpose of this paper is to take some initial steps in this direction. Specifically, we derive general exact relations for thermodynamic properties (energy, pressure, and isothermal compressibility) that apply to any ground-state ensemble as a function of ρ in any d , and we show how disordered degenerate ground states arise as part of the ground-state manifold. We also derive exact integral conditions that both the pair correlation function g2(r ) and structure factor S (k ) must obey for any d . We then specialize our results to the canonical ensemble (in the zero-temperature limit) by exploiting an ansatz that stealthy states behave remarkably like "pseudo"-equilibrium hard-sphere systems in Fourier space. Our theoretical predictions for g2(r ) and S (k ) are in excellent agreement with computer simulations across the first three space dimensions. These results are used to obtain order metrics, local number variance, and nearest-neighbor functions across dimensions. We also derive accurate analytical
Mukherjee, Sutirtha; Mandal, Sudhansu
The internal structure and topology of the ground states for fractional quantum Hall effect (FQHE) are determined by the relative angular momenta between all the possible pairs of electrons. Laughlin wave function is the only known microscopic wave function for which these relative angular momenta are homogeneous (same) for any pair of electrons and depend solely on the filling factor. Without invoking any microscopic theory, considering only the relationship between number of flux quanta and particles in spherical geometry, and allowing the possibility of inhomogeneous (different) relative angular momenta between any two electrons, we develop a general method for determining a closed-form ground state wave function for any incompressible FQHE state. Our procedure provides variationally obtained very accurate wave functions, yet having simpler structure compared to any other known complex microscopic wave functions for the FQHE states. This method, thus, has potential in predicting a very accurate ground state wave function for the puzzling states such as the state at filling fraction 5/2. We acknowledge support from Department of Science and Technology, India.
Modeling of Internal State and Performance of an Ironmaking Blast Furnace: Slot vs Sector Geometries
Shen, Yansong; Guo, Baoyu; Chew, Sheng; Austin, Peter; Yu, Aibing
2016-04-01
Mathematical modeling is a cost-effective method to understand internal state and predict performance of ironmaking blast furnace (BF) for improving productivity and maintaining stability. In the past studies, both slot and sector geometries were used for BF modeling. In this paper, a mathematical model is described for simulating the complex behaviors of solid, gas and liquid multiphase flow, heat and mass transfers, and chemical reactions in a BF. Then the model is used to compare different model configurations, viz. slot and sector geometries by investigating their effects on predicted behaviors, in terms of two aspects: (i) internal state including cohesive zone, velocity, temperature, components concentration, reduction degree, gas utilization, and (ii) performance indicators including liquid output at the bottom and gas utilization rate at the furnace top. The comparisons show that on one hand, predictions of internal state of the furnace such as fluid flow and thermo-chemical phenomena using the slot and sector geometries are qualitatively comparable but quantitatively different. Both sector and slot geometries give a similar cohesive zone shape but the sector geometry gives a higher cohesive zone near the wall and faster reduction. On the other hand, the two geometries can produce similar performance indicators including gas utilization at the furnace top and liquid output at the bottom. Such a study is useful in selecting geometry for numerically examining BF operation with respect to different needs.
Quench of a symmetry-broken ground state
Giampaolo, S. M.; Zonzo, G.
2017-01-01
We analyze the problem of how different ground states associated with the same set of Hamiltonian parameters evolve after a sudden quench. To realize our analysis we define a quantitative approach to the local distinguishability between different ground states of a magnetically ordered phase in terms of the trace distance between the reduced density matrices obtained by projecting two ground states in the same subset. Before the quench, regardless of the particular choice of subset, any system in a magnetically ordered phase is characterized by ground states that are locally distinguishable. On the other hand, after the quench, the maximum distinguishability shows an exponential decay in time. Hence, in the limit of very long times, all the information about the particular initial ground state is lost even if the systems are integrable. We prove our claims in the framework of the magnetically ordered phases that characterize both the X Y and the N -cluster Ising models. The fact that we find similar behavior in models within different classes of symmetry makes us confident about the generality of our results.
Borromean ground state of fermions in two dimensions
Volosniev, A. G.; Fedorov, D. V.; Jensen, A. S.; Zinner, N. T.
2014-09-01
The study of quantum mechanical bound states is as old as quantum theory itself. Yet, it took many years to realize that three-body Borromean systems that are bound when any two-body subsystem is unbound are abundant in nature. Here we demonstrate the existence of Borromean systems of spin-polarized (spinless) identical fermions in two spatial dimensions. The ground state with zero orbital (planar) angular momentum exists in a Borromean window between critical two- and three-body strengths. The doubly degenerate first excited states of angular momentum one appears only very close to the two-body threshold. They are the lowest in a possible sequence of so-called super-Efimov states. While the observation of the super-Efimov scaling could be very difficult, the Borromean ground state should be observable in cold atomic gases and could be the basis for producing a quantum gas of three-body states in two dimensions.
Ground Truth Events with Source Geometry in Eurasia and the Middle East
2016-06-02
in Saudi Arabia, 5 in Ethiopia, and 10 in Tanzania with magnitudes of 3 or greater. Source parameters were obtained through moment tensor inversions...TERMS seismic location; seismic ground truth; seismic moment tensor 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18. NUMBER OF PAGES...Arabia ..................... 4 Figure 2. Results from the grid search and moment tensor inversion for source mechanisms for events in Saudi Arabia
Oglesby, David D.
2012-03-01
Using the 3-D finite-element method, we develop dynamic spontaneous rupture models of earthquakes on the North Anatolian Fault system in the Sea of Marmara, Turkey, considering the geometrical complexity of the fault system in this region. We find that the earthquake size, rupture propagation pattern and ground motion all strongly depend on the interplay between the initial (static) regional pre-stress field and the dynamic stress field radiated by the propagating rupture. By testing several nucleation locations, we observe that those far from an oblique normal fault stepover segment (near Istanbul) lead to large through-going rupture on the entire fault system, whereas nucleation locations closer to the stepover segment tend to produce ruptures that die out in the stepover. However, this pattern can change drastically with only a 10° rotation of the regional stress field. Our simulations also reveal that while dynamic unclamping near fault bends can produce a new mode of supershear rupture propagation, this unclamping has a much smaller effect on the speed of the peak in slip velocity along the fault. Finally, we find that the complex fault geometry leads to a very complex and asymmetric pattern of near-fault ground motion, including greatly amplified ground motion on the insides of fault bends. The ground-motion pattern can change significantly with different hypocentres, even beyond the typical effects of directivity. The results of this study may have implications for seismic hazard in this region, for the dynamics and ground motion of geometrically complex faults, and for the interpretation of kinematic inverse rupture models.
Ferromagnetic Ground States in Face-Centered Cubic Hubbard Clusters
Souza, T. X. R.; Macedo, C. A.
2016-01-01
In this study, the ground state energies of face-centered cubic Hubbard clusters are analyzed using the Lanczos method. Examination of the ground state energy as a function of the number of particle per site n showed an energy minimum for face-centered cubic structures. This energy minimum decreased in n with increasing coulombic interaction parameter U. We found that the ground state energy had a minimum at n = 0.6, when U = 3W, where W denotes the non-interacting energy bandwidth and the face-centered cubic structure was ferromagnetic. These results, when compared with the properties of nickel, shows strong similarity with other finite temperature analyses in the literature and supports the Hirsh’s conjecture that the interatomic direct exchange interaction dominates in driving the system into a ferromagnetic phase. PMID:27583653
Estimation of beryllium ground state energy by Monte Carlo simulation
Energy Technology Data Exchange (ETDEWEB)
Kabir, K. M. Ariful [Department of Physical Sciences, School of Engineering and Computer Science, Independent University, Bangladesh (IUB) Dhaka (Bangladesh); Halder, Amal [Department of Mathematics, University of Dhaka Dhaka (Bangladesh)
2015-05-15
Quantum Monte Carlo method represent a powerful and broadly applicable computational tool for finding very accurate solution of the stationary Schrödinger equation for atoms, molecules, solids and a variety of model systems. Using variational Monte Carlo method we have calculated the ground state energy of the Beryllium atom. Our calculation are based on using a modified four parameters trial wave function which leads to good result comparing with the few parameters trial wave functions presented before. Based on random Numbers we can generate a large sample of electron locations to estimate the ground state energy of Beryllium. Our calculation gives good estimation for the ground state energy of the Beryllium atom comparing with the corresponding exact data.
Probing quantum frustrated systems via factorization of the ground state.
Giampaolo, Salvatore M; Adesso, Gerardo; Illuminati, Fabrizio
2010-05-21
The existence of definite orders in frustrated quantum systems is related rigorously to the occurrence of fully factorized ground states below a threshold value of the frustration. Ground-state separability thus provides a natural measure of frustration: strongly frustrated systems are those that cannot accommodate for classical-like solutions. The exact form of the factorized ground states and the critical frustration are determined for various classes of nonexactly solvable spin models with different spatial ranges of the interactions. For weak frustration, the existence of disentangling transitions determines the range of applicability of mean-field descriptions in biological and physical problems such as stochastic gene expression and the stability of long-period modulated structures.
Analysis of ground state in random bipartite matching
Shi, Gui-Yuan; Liao, Hao; Zhang, Yi-Cheng
2015-01-01
In human society, a lot of social phenomena can be concluded into a mathematical problem called the bipartite matching, one of the most well known model is the marriage problem proposed by Gale and Shapley. In this article, we try to find out some intrinsic properties of the ground state of this model and thus gain more insights and ideas about the matching problem. We apply Kuhn-Munkres Algorithm to find out the numerical ground state solution of the system. The simulation result proves the previous theoretical analysis using replica method. In the result, we also find out the amount of blocking pairs which can be regarded as a representative of the system stability. Furthermore, we discover that the connectivity in the bipartite matching problem has a great impact on the stability of the ground state, and the system will become more unstable if there were more connections between men and women.
Ground states of the SU(N) Heisenberg model.
Kawashima, Naoki; Tanabe, Yuta
2007-02-02
The SU(N) Heisenberg model with various single-row representations is investigated by quantum Monte Carlo simulations. While the zero-temperature phase boundary agrees qualitatively with the theoretical predictions based on the 1/N expansion, some unexpected features are also observed. For N> or =5 with the fundamental representation, for example, it is suggested that the ground states possess exact or approximate U(1) degeneracy. In addition, for the representation of Young tableau with more than one column, the ground state shows no valence-bond-solid order even at N greater than the threshold value.
Ground state properties of graphene in Hartree-Fock theory
Hainzl, Christian; Sparber, Christof
2012-01-01
We study the Hartree-Fock approximation of graphene in infinite volume, with instantaneous Coulomb interactions. First we construct its translation-invariant ground state and we recover the well-known fact that, due to the exchange term, the effective Fermi velocity is logarithmically divergent at zero momentum. In a second step we prove the existence of a ground state in the presence of local defects and we discuss some properties of the linear response to an external electric field. All our results are non perturbative.
Coherent Control of Ground State NaK Molecules
Yan, Zoe; Park, Jee Woo; Loh, Huanqian; Will, Sebastian; Zwierlein, Martin
2016-05-01
Ultracold dipolar molecules exhibit anisotropic, tunable, long-range interactions, making them attractive for the study of novel states of matter and quantum information processing. We demonstrate the creation and control of 23 Na40 K molecules in their rovibronic and hyperfine ground state. By applying microwaves, we drive coherent Rabi oscillations of spin-polarized molecules between the rotational ground state (J=0) and J=1. The control afforded by microwave manipulation allows us to pursue engineered dipolar interactions via microwave dressing. By driving a two-photon transition, we are also able to observe Ramsey fringes between different J=0 hyperfine states, with coherence times as long as 0.5s. The realization of long coherence times between different molecular states is crucial for applications in quantum information processing. NSF, AFOSR- MURI, Alfred P. Sloan Foundation, DARPA-OLE
Geometry of state space in plane Couette flow
Cvitanović, P.; Gibson, J. F.
A large conceptual gap separates the theory of low-dimensional chaotic dynamics from the infinite-dimensional nonlinear dynamics of turbulence. Recent advances in experimental imaging, computational methods, and dynamical systems theory suggest a way to bridge this gap in our understanding of turbulence. Recent discoveries show that recurrent coherent structures observed in wall-bounded shear flows (such as pipes and plane Couette flow) result from close passes to weakly unstable invariant solutions of the Navier-Stokes equations. These 3D, fully nonlinear solutions (equilibria, traveling waves, and periodic orbits) structure the state space of turbulent flows and provide a skeleton for analyzing their dynamics. We calculate a hierarchy of invariant solutions for plane Couette, a canonical wall-bounded shear flow. These solutions reveal organization in the flow's turbulent dynamics and can be used to predict directly from the fundamental equations physical quantities such as bulk flow rate and mean wall drag. All results and the code that generates them are disseminated through through our group's open-source CFD software and solution database Channelflow.org and the collaborative e-book ChaosBook.org.
Striped spin liquid crystal ground state instability of kagome antiferromagnets.
Clark, Bryan K; Kinder, Jesse M; Neuscamman, Eric; Chan, Garnet Kin-Lic; Lawler, Michael J
2013-11-01
The Dirac spin liquid ground state of the spin 1/2 Heisenberg kagome antiferromagnet has potential instabilities. This has been suggested as the reason why it does not emerge as the ground state in large-scale numerical calculations. However, previous attempts to observe these instabilities have failed. We report on the discovery of a projected BCS state with lower energy than the projected Dirac spin liquid state which provides new insight into the stability of the ground state of the kagome antiferromagnet. The new state has three remarkable features. First, it breaks spatial symmetry in an unusual way that may leave spinons deconfined along one direction. Second, it breaks the U(1) gauge symmetry down to Z(2). Third, it has the spatial symmetry of a previously proposed "monopole" suggesting that it is an instability of the Dirac spin liquid. The state described herein also shares a remarkable similarity to the distortion of the kagome lattice observed at low Zn concentrations in Zn-paratacamite and in recently grown single crystals of volborthite suggesting it may already be realized in these materials.
Gimbert, F.; Tsai, V. C.; Amundson, J. M.; Bartholomaus, T. C.; Walter, J. I.
2016-12-01
Water from ice melt and precipitation that flows to and pressurizes the base of glaciers contributes to glacier and ice sheet acceleration. Predicting acceleration and its impact on ice mass loss and sea-level rise under global climate warming therefore requires knowledge of subglacial channel evolution and water pressurization, which remains limited by a lack of observations. Here we show that ground motion caused by subglacial channel flow at Mendenhall Glacier (Alaska) can be used to recover simultaneously basal water pressure, channel geometry and sediment transport throughout the melt season. We provide observations of the interplay between these physical quantities and discuss the implications for glacier sliding and erosion. By constraining the physics of subglacial hydrology, our framework and its application to outlet glaciers of the Greenland and Antarctic ice sheets may lead to more reliable predictions of ice flow, sea level rise and subglacial erosion rates.
Asymptotics of Ground State Degeneracies in Quiver Quantum Mechanics
Cordova, Clay
2015-01-01
We study the growth of the ground state degeneracy in the Kronecker model of quiver quantum mechanics. This is the simplest quiver with two gauge groups and bifundamental matter fields, and appears universally in the context of BPS state counting in four-dimensional N=2 systems. For large ranks, the ground state degeneracy is exponential with slope a modular function that we are able to compute at integral values of its argument. We also observe that the exponential of the slope is an algebraic number and determine its associated algebraic equation explicitly in several examples. The speed of growth of the degeneracies, together with various physical features of the bound states, suggests a dual string interpretation.
State-Space Geometry, Statistical Fluctuations, and Black Holes in String Theory
Directory of Open Access Journals (Sweden)
Stefano Bellucci
2014-01-01
Full Text Available We study the state-space geometry of various extremal and nonextremal black holes in string theory. From the notion of the intrinsic geometry, we offer a state-space perspective to the black hole vacuum fluctuations. For a given black hole entropy, we explicate the intrinsic geometric meaning of the statistical fluctuations, local and global stability conditions, and long range statistical correlations. We provide a set of physical motivations pertaining to the extremal and nonextremal black holes, namely, the meaning of the chemical geometry and physics of correlation. We illustrate the state-space configurations for general charge extremal black holes. In sequel, we extend our analysis for various possible charge and anticharge nonextremal black holes. From the perspective of statistical fluctuation theory, we offer general remarks, future directions, and open issues towards the intrinsic geometric understanding of the vacuum fluctuations and black holes in string theory.
Observation of Hyperfine Transitions in Trapped Ground-State Antihydrogen
Olin, Arthur
2015-01-01
This paper discusses the first observation of stimulated magnetic resonance transitions between the hyperfine levels of trapped ground state atomic antihydrogen, confirming its presence in the ALPHA apparatus. Our observations show that these transitions are consistent with the values in hydrogen to within 4~parts~in~$10^3$. Simulations of the trapped antiatoms in a microwave field are consistent with our measurements.
Advantages of Unfair Quantum Ground-State Sampling.
Zhang, Brian Hu; Wagenbreth, Gene; Martin-Mayor, Victor; Hen, Itay
2017-04-21
The debate around the potential superiority of quantum annealers over their classical counterparts has been ongoing since the inception of the field. Recent technological breakthroughs, which have led to the manufacture of experimental prototypes of quantum annealing optimizers with sizes approaching the practical regime, have reignited this discussion. However, the demonstration of quantum annealing speedups remains to this day an elusive albeit coveted goal. We examine the power of quantum annealers to provide a different type of quantum enhancement of practical relevance, namely, their ability to serve as useful samplers from the ground-state manifolds of combinatorial optimization problems. We study, both numerically by simulating stoquastic and non-stoquastic quantum annealing processes, and experimentally, using a prototypical quantum annealing processor, the ability of quantum annealers to sample the ground-states of spin glasses differently than thermal samplers. We demonstrate that (i) quantum annealers sample the ground-state manifolds of spin glasses very differently than thermal optimizers (ii) the nature of the quantum fluctuations driving the annealing process has a decisive effect on the final distribution, and (iii) the experimental quantum annealer samples ground-state manifolds significantly differently than thermal and ideal quantum annealers. We illustrate how quantum annealers may serve as powerful tools when complementing standard sampling algorithms.
On the Ground State Wave Function of Matrix Theory
Lin, Ying-Hsuan
2014-01-01
We propose an explicit construction of the leading terms in the asymptotic expansion of the ground state wave function of BFSS SU(N) matrix quantum mechanics. Our proposal is consistent with the expected factorization property in various limits of the Coulomb branch, and involves a different scaling behavior from previous suggestions. We comment on some possible physical implications.
On the ground state wave function of matrix theory
Lin, Ying-Hsuan; Yin, Xi
2015-11-01
We propose an explicit construction of the leading terms in the asymptotic expansion of the ground state wave function of BFSS SU( N ) matrix quantum mechanics. Our proposal is consistent with the expected factorization property in various limits of the Coulomb branch, and involves a different scaling behavior from previous suggestions. We comment on some possible physical implications.
^{66}Ga ground state β spectrum
DEFF Research Database (Denmark)
Severin, Gregory; Knutson, L. D.; Voytas, P. A.;
2014-01-01
The ground state branch of the β decay of 66Ga is an allowed Fermi (0+ → 0+) transition with a relatively high f t value. The large f t and the isospin-forbidden nature of the transition indicates that the shape of the β spectrum of this branch may be sensitive to higher order contributions...
Magnetic excitons in singlet-ground-state ferromagnets
DEFF Research Database (Denmark)
Birgeneau, R.J.; Als-Nielsen, Jens Aage; Bucher, E.
1971-01-01
The authors report measurements of the dispersion of singlet-triplet magnetic excitons as a function of temperature in the singlet-ground-state ferromagnets fcc Pr and Pr3Tl. Well-defined excitons are observed in both the ferromagnetic and paramagnetic regions, but with energies which are nearly...
Ground-state charge transfer as a mechanism for surface-enhanced Raman scattering
Lippitsch, Max E.
1984-03-01
A model is presented for the contribution of ground-state charge transfer between a metal and adsorbate to surface-enhanced Raman scattering (SERS). It is shown that this contribution can be understood using the vibronic theory for calculating Raman intensities. The enhancement is due to vibronic coupling of the molecular ground state to the metal states, the coupling mechanism being a modulation of the ground-state charge-transfer energy by the molecular vibrations. An analysis of the coupling operator gives the selection rules for this process, which turn out to be dependent on the overall symmetry of the adsorbate-metal system, even if the charge transfer is small enough for the symmetry of the adsorbate to remain the same as that of the free molecule. It is shown that the model can yield predictions on the properties of SERS, e.g., specificity to adsorption geometry, appearance of forbidden bands, dependence on the applied potential, and dependence on the excitation wavelength. The predictions are in good agreement with experimental results. It is also deduced from this model that in many cases atomic-scale roughness is a prerequisite for the observation of SERS. A result on the magnitude of the enhancement can only be given in a crude approximation. Although in most cases an additional electromagnetic enhancement seems to be necessary to give an observable signal, this charge-transfer mechanism should be important in many SERS systems.
Hu, Weifeng
2015-01-01
We describe and extend the formalism of state-specific analytic density matrix renormalization group (DMRG) energy gradients, first used by Liu et al (J. Chem. Theor.Comput. 9, 4462 (2013)). We introduce a DMRG wavefunction maximum overlap following technique to facilitate state-specific DMRG excited state optimization. Using DMRG configuration interaction (DMRG-CI) gradients we relax the low-lying singlet states of a series of trans-polyenes up to C20H22. Using the relaxed excited state geometries as well as correlation functions, we elucidate the exciton, soliton, and bimagnon ("single-fission") character of the excited states, and find evidence for a planar conical intersection.
Collective excitations, instabilities, and ground state in dense quark matter
Gorbar, E V; Miransky, V A; Shovkovy, I A; Hashimoto, Michio
2006-01-01
We study the spectrum of light plasmons in the (gapped and gapless) two-flavor color superconducting phases and its connection with the chromomagnetic instabilities and the structure of the ground state. It is revealed that the chromomagnetic instabilities in the 4-7th and 8th gluonic channels correspond to two very different plasmon spectra. These spectra lead us to the unequivocal conclusion about the existence of gluonic condensates (some of which can be spatially inhomogeneous) in the ground state. We also argue that spatially inhomogeneous gluonic condensates should exist in the three-flavor quark matter with the values of the mass of strange quark corresponding to the gapless color-flavor locked state.
Directory of Open Access Journals (Sweden)
Logan D Andrews
2013-07-01
Full Text Available Enzymes stabilize transition states of reactions while limiting binding to ground states, as is generally required for any catalyst. Alkaline Phosphatase (AP and other nonspecific phosphatases are some of Nature's most impressive catalysts, achieving preferential transition state over ground state stabilization of more than 10²²-fold while utilizing interactions with only the five atoms attached to the transferred phosphorus. We tested a model that AP achieves a portion of this preference by destabilizing ground state binding via charge repulsion between the anionic active site nucleophile, Ser102, and the negatively charged phosphate monoester substrate. Removal of the Ser102 alkoxide by mutation to glycine or alanine increases the observed Pi affinity by orders of magnitude at pH 8.0. To allow precise and quantitative comparisons, the ionic form of bound P(i was determined from pH dependencies of the binding of Pi and tungstate, a P(i analog lacking titratable protons over the pH range of 5-11, and from the ³¹P chemical shift of bound P(i. The results show that the Pi trianion binds with an exceptionally strong femtomolar affinity in the absence of Ser102, show that its binding is destabilized by ≥10⁸-fold by the Ser102 alkoxide, and provide direct evidence for ground state destabilization. Comparisons of X-ray crystal structures of AP with and without Ser102 reveal the same active site and P(i binding geometry upon removal of Ser102, suggesting that the destabilization does not result from a major structural rearrangement upon mutation of Ser102. Analogous Pi binding measurements with a protein tyrosine phosphatase suggest the generality of this ground state destabilization mechanism. Our results have uncovered an important contribution of anionic nucleophiles to phosphoryl transfer catalysis via ground state electrostatic destabilization and an enormous capacity of the AP active site for specific and strong recognition of the
Fate of the Superconducting Ground State on the Moyal Plane
Basu, Prasad; Vaidya, Sachindeo
2009-01-01
It is known that Berry curvature of the band structure of certain crystals can lead to effective noncommutativity between spatial coordinates. Using the techniques of twisted quantum field theory, we investigate the question of the formation of a paired state of twisted fermions in such a system. We find that to leading order in the noncommutativity parameter, the gap between the non-interacting ground state and the paired state is {\\it smaller} compared to its commutative counterpart. This suggests that BCS type superconductivity, if present in such systems, is more fragile and easier to disrupt.
Energy Technology Data Exchange (ETDEWEB)
Aryanpour, Karan [Department of Physics, University of Arizona, Tucson, Arizona 85721 (United States); Shukla, Alok [Department of Physics, Indian Institute of Technology, Powai, Mumbai 400076 (India); Mazumdar, Sumit [Department of Physics, University of Arizona, Tucson, Arizona 85721 (United States); College of Optical Sciences, University of Arizona, Tucson, Arizona 85721 (United States)
2014-03-14
We present numerical studies of one- and two-photon excited states ordering in a number of polycyclic aromatic hydrocarbon molecules: coronene, hexa-peri-hexabenzocoronene, and circumcoronene, all possessing D{sub 6h} point group symmetry versus ovalene with D{sub 2h} symmetry, within the Pariser-Parr-Pople model of interacting π-electrons. The calculated energies of the two-photon states as well as their relative two-photon absorption cross-sections within the interacting model are qualitatively different from single-particle descriptions. More remarkably, a peculiar role of molecular geometry is found. The consequence of electron correlations is far stronger for ovalene, where the lowest spin-singlet two-photon state is a quantum superposition of pairs of lowest spin triplet states, as in the linear polyenes. The same is not true for D{sub 6h} group hydrocarbons. Our work indicates significant covalent character, in valence bond language, of the ground state, the lowest spin triplet state and a few of the lowest two-photon states in D{sub 2h} ovalene but not in those with D{sub 6h} symmetry.
Aryanpour, Karan; Shukla, Alok; Mazumdar, Sumit
2014-03-01
We present numerical studies of one- and two-photon excited states ordering in a number of polycyclic aromatic hydrocarbon molecules: coronene, hexa-peri-hexabenzocoronene, and circumcoronene, all possessing D6h point group symmetry versus ovalene with D2h symmetry, within the Pariser-Parr-Pople model of interacting π-electrons. The calculated energies of the two-photon states as well as their relative two-photon absorption cross-sections within the interacting model are qualitatively different from single-particle descriptions. More remarkably, a peculiar role of molecular geometry is found. The consequence of electron correlations is far stronger for ovalene, where the lowest spin-singlet two-photon state is a quantum superposition of pairs of lowest spin triplet states, as in the linear polyenes. The same is not true for D6h group hydrocarbons. Our work indicates significant covalent character, in valence bond language, of the ground state, the lowest spin triplet state and a few of the lowest two-photon states in D2h ovalene but not in those with D6h symmetry.
Mixed configuration ground state in iron(II) phthalocyanine
Energy Technology Data Exchange (ETDEWEB)
Fernandez-Rodriguez, Javier; Toby, Brian; van Veenendaal, Michel
2015-06-23
We calculate the angular dependence of the x-ray linear and circular dichroism at the L2,3 edges of α-Fe(II) Phthalocyanine (FePc) thin films using a ligand-field model with full configuration interaction. We find the best agreement with the experimental spectra for a mixed ground state of 3E (a2 e3b1 ) and 3B (a1 e4b1 ) g 1g g 2g 2g 1g g 2g with the two configurations coupled by the spin-orbit interaction. The 3Eg(b) and 3B2g states have easy-axis and easy-plane anisotropies, respectively. Our model accounts for an easy-plane magnetic anisotropy and the measured magnitudes of the in-plane orbital and spin moments. The proximity in energy of the two configurations allows a switching of the magnetic anisotropy from easy plane to easy axis with a small change in the crystal field, as recently observed for FePc adsorbed on an oxidized Cu surface. We also discuss the possibility of a quintet ground state (5A1g is 250 meV above the ground state) with planar anisotropy by manipulation of the Fe-C bond length by depositing the complex on a substrate that is subjected to a mechanical strain.
Mihaila, Bogdan; Heisenberg, Jochen
2000-04-01
We continue the investigations of ground state properties of closed-shell nuclei using the Argonne v18 realistic NN potential, together with the Urbana IX three-nucleon interaction. The ground state wave function is used to calculate the charge form factor and charge density. Starting with the ground state wave function of the closed-shell nucleus, we use the equation of motion technique to calculate the ground state and excited states of a neighboring nucleus. We then generate the corresponding magnetic form factor. We correct for distortions due to the interaction between the electron probe and the nuclear Coulomb field using the DWBA picture. We compare our results with the available experimental data. Even though our presentation will focus mainly on the ^16O and ^15N nuclei, results for other nuclei in the p and s-d shell will also be presented.
Barborini, Matteo; Guidoni, Leonardo
2016-09-01
The correct description of the ground state electronic and geometrical properties of multi-centre transition metal complexes necessitates of a high-level description of both dynamical and static correlation effects. In di-metallic complexes, the ground state low spin properties can be computed starting from single-determinants High-Spin (HS) and Broken Symmetry (BS) states by reconstructing an approximated low spin potential energy surface through the extended broken symmetry approach, based on the Heisenberg Hamiltonian. In the present work, we first apply this approach within the variational Monte Carlo method to tackle the geometry optimization of a Fe2S2(SH)42- model complex. To describe the HS and BS wavefunctions, we use a fully optimized unrestricted single determinant with a correlated Jastrow factor able to recover a large amount of dynamical correlation. We compared our results with those obtained by density functional theory and other multiconfigurational approaches, discussing the role of the nodal surface on the structural parameters.
McAnally, Michael O.; Hlavacek, Nikolaus C.; Drucker, Stephen
2012-06-01
The spectroscopically derived inertial constants for acrolein (propenal) in its T_1(n,π*) state were used to test predictions from a variety of computational methods. One focus was on multiconfigurational methods, such as CASSCF and CASPT2, that are applicable to excited states. We also examined excited-state methods that utilize single reference configurations, including EOM-EE-CCSD and TD-PBE0. Finally, we applied unrestricted ground-state techniques, such as UCCSD(T) and the more economical UPBE0 method, to the T_1(n,π*) excited state under the constraint of C_s symmetry. The unrestricted ground-state methods are applicable because at a planar geometry, the T_1(n,π*) state of acrolein is the lowest-energy state of its spin multiplicity. Each of the above methods was used with a triple zeta quality basis set to optimize the T_1(n,π*) geometry. This procedure resulted in the following sets of inertial constants: Inertial constants (cm-1) of acrolein in its T_1(n,π*) state Method A B C Method A B C CASPT2(6,5) 1.667 0.1491 0.1368 UCCSD(T)^b 1.668 0.1480 0.1360 CASSCF(6,5) 1.667 0.1491 0.1369 UPBE0 1.699 0.1487 0.1367 EOM-EE-CCSD 1.675 0.1507 0.1383 TD-PBE0 1.719 0.1493 0.1374 Experiment^a 1.662 0.1485 0.1363 The two multiconfigurational methods produce the same inertial constants, and those constants agree closely with experiment. However the sets of computed bond lengths differ significantly for the two methods. In the CASSCF calculation, the lengthening of the C=O and C=C bonds and the shortening of the C--C bond are more pronounced than in CASPT2. O. S. Bokareva et al., Int. J. Quant. Chem. {108}, 2719 (2008).
Simulation of the hydrogen ground state in stochastic electrodynamics
Nieuwenhuizen, Theo M.; Liska, Matthew T. P.
2015-10-01
Stochastic electrodynamics is a classical theory which assumes that the physical vacuum consists of classical stochastic fields with average energy \\frac{1}{2}{{\\hslash }}ω in each mode, i.e., the zero-point Planck spectrum. While this classical theory explains many quantum phenomena related to harmonic oscillator problems, hard results on nonlinear systems are still lacking. In this work the hydrogen ground state is studied by numerically solving the Abraham-Lorentz equation in the dipole approximation. First the stochastic Gaussian field is represented by a sum over Gaussian frequency components, next the dynamics is solved numerically using OpenCL. The approach improves on work by Cole and Zou 2003 by treating the full 3d problem and reaching longer simulation times. The results are compared with a conjecture for the ground state phase space density. Though short time results suggest a trend towards confirmation, in all attempted modellings the atom ionises at longer times.
Ground-State Phase Diagram of S = 1 Diamond Chains
Hida, Kazuo; Takano, Ken'ichi
2017-03-01
We investigate the ground-state phase diagram of a spin-1 diamond chain. Owing to a series of conservation laws, any eigenstate of this system can be expressed using the eigenstates of finite odd-length chains or infinite chains with spins 1 and 2. The ground state undergoes quantum phase transitions with varying λ, a parameter that controls frustration. Exact upper and lower bounds for the phase boundaries between these phases are obtained. The phase boundaries are determined numerically in the region not explored in a previous work [Takano et al., https://doi.org/10.1088/0953-8984/8/35/009" xlink:type="simple">J. Phys.: Condens. Matter 8, 6405 (1996)].
Cluster expansion for ground states of local Hamiltonians
Bastianello, Alvise; Sotiriadis, Spyros
2016-08-01
A central problem in many-body quantum physics is the determination of the ground state of a thermodynamically large physical system. We construct a cluster expansion for ground states of local Hamiltonians, which naturally incorporates physical requirements inherited by locality as conditions on its cluster amplitudes. Applying a diagrammatic technique we derive the relation of these amplitudes to thermodynamic quantities and local observables. Moreover we derive a set of functional equations that determine the cluster amplitudes for a general Hamiltonian, verify the consistency with perturbation theory and discuss non-perturbative approaches. Lastly we verify the persistence of locality features of the cluster expansion under unitary evolution with a local Hamiltonian and provide applications to out-of-equilibrium problems: a simplified proof of equilibration to the GGE and a cumulant expansion for the statistics of work, for an interacting-to-free quantum quench.
Ground-state structures of atomic metallic hydrogen.
McMahon, Jeffrey M; Ceperley, David M
2011-04-22
Ab initio random structure searching using density functional theory is used to determine the ground-state structures of atomic metallic hydrogen from 500 GPa to 5 TPa. Including proton zero-point motion within the harmonic approximation, we estimate that molecular hydrogen dissociates into a monatomic body-centered tetragonal structure near 500 GPa (r(s)=1.23) that remains stable to 1 TPa (r(s)=1.11). At higher pressures, hydrogen stabilizes in an …ABCABC… planar structure that is similar to the ground state of lithium, but with a different stacking sequence. With increasing pressure, this structure compresses to the face-centered cubic lattice near 3.5 TPa (r(s)=0.92).
Ground-state rotational constants of 12CH 3D
Chackerian, C.; Guelachvili, G.
1980-12-01
An analysis of ground-state combination differences in the ν2( A1) fundamental band of 12CH 3D ( ν0 = 2200.03896 cm -1) has been made to yield values for the rotational constants B0, D0J, D0JK, H0JJJ, H0JJK, H0JKK, LJJJJ, L0JJJK, and order of magnitude values for L0JJKK and L0JKKK. These constants should be useful in assisting radio searches for this molecule in astrophysical sources. In addition, splittings of A1A2 levels ( J ≥ 17, K = 3) have been measured in both the ground and excited vibrational states of this band.
Non-uniform ground state for the Bose gas
2000-01-01
We study the ground state, sum a_X |X>, of N hard-core bosons on a finite lattice in configuration space, X={x_1,...,x_N}. All a_X being positive, the ratios a_X / sum a_Y can be interpreted as probabilities P_a (X). Let E denote the energy of the ground state and B_X the number of nearest-neighbor particle-hole pairs in the configuration X. We prove the concentration of P_a to X's with B_X in a sqrt(|E|)-neighborhood of |E|, show that the average of a_X over configurations with B_X=n increas...
Cluster expansion for ground states of local Hamiltonians
Directory of Open Access Journals (Sweden)
Alvise Bastianello
2016-08-01
Full Text Available A central problem in many-body quantum physics is the determination of the ground state of a thermodynamically large physical system. We construct a cluster expansion for ground states of local Hamiltonians, which naturally incorporates physical requirements inherited by locality as conditions on its cluster amplitudes. Applying a diagrammatic technique we derive the relation of these amplitudes to thermodynamic quantities and local observables. Moreover we derive a set of functional equations that determine the cluster amplitudes for a general Hamiltonian, verify the consistency with perturbation theory and discuss non-perturbative approaches. Lastly we verify the persistence of locality features of the cluster expansion under unitary evolution with a local Hamiltonian and provide applications to out-of-equilibrium problems: a simplified proof of equilibration to the GGE and a cumulant expansion for the statistics of work, for an interacting-to-free quantum quench.
The ground state in a spin-one color superconductor
Schmitt, A
2004-01-01
Color superconductors in which quarks of the same flavor form Cooper pairs are investigated. These Cooper pairs carry total spin one. A systematic group-theoretical classification of possible phases in a spin-one color superconductor is presented, revealing parallels and differences to the theory of superfluid $^3$He. General expressions for the gap parameter, the critical temperature, and the pressure are derived and evaluated for several spin-one phases, with special emphasis on the angular structure of the gap equation. It is shown that, in a spin-one color superconductor, the (transverse) A phase is expected to be the ground state. This is in contrast to $^3$He, where the ground state is in the B phase.
EIT ground-state cooling of long ion strings
Lechner, R; Hempel, C; Jurcevic, P; Lanyon, B P; Monz, T; Brownnutt, M; Blatt, R; Roos, C F
2016-01-01
Electromagnetically-induced-transparency (EIT) cooling is a ground-state cooling technique for trapped particles. EIT offers a broader cooling range in frequency space compared to more established methods. In this work, we experimentally investigate EIT cooling in strings of trapped atomic ions. In strings of up to 18 ions, we demonstrate simultaneous ground state cooling of all radial modes in under 1 ms. This is a particularly important capability in view of emerging quantum simulation experiments with large numbers of trapped ions. Our analysis of the EIT cooling dynamics is based on a novel technique enabling single-shot measurements of phonon numbers, by rapid adiabatic passage on a vibrational sideband of a narrow transition.
Cluster expansion for ground states of local Hamiltonians
Energy Technology Data Exchange (ETDEWEB)
Bastianello, Alvise, E-mail: abastia@sissa.it [SISSA, via Bonomea 265, 34136 Trieste (Italy); INFN, Sezione di Trieste (Italy); Sotiriadis, Spyros [SISSA, via Bonomea 265, 34136 Trieste (Italy); INFN, Sezione di Trieste (Italy); Institut de Mathématiques de Marseille (I2M), Aix Marseille Université, CNRS, Centrale Marseille, UMR 7373, 39, rue F. Joliot Curie, 13453, Marseille (France); University of Roma Tre, Department of Mathematics and Physics, L.go S.L. Murialdo 1, 00146 Roma (Italy)
2016-08-15
A central problem in many-body quantum physics is the determination of the ground state of a thermodynamically large physical system. We construct a cluster expansion for ground states of local Hamiltonians, which naturally incorporates physical requirements inherited by locality as conditions on its cluster amplitudes. Applying a diagrammatic technique we derive the relation of these amplitudes to thermodynamic quantities and local observables. Moreover we derive a set of functional equations that determine the cluster amplitudes for a general Hamiltonian, verify the consistency with perturbation theory and discuss non-perturbative approaches. Lastly we verify the persistence of locality features of the cluster expansion under unitary evolution with a local Hamiltonian and provide applications to out-of-equilibrium problems: a simplified proof of equilibration to the GGE and a cumulant expansion for the statistics of work, for an interacting-to-free quantum quench.
Room temperature skyrmion ground state stabilized through interlayer exchange coupling
Energy Technology Data Exchange (ETDEWEB)
Chen, Gong, E-mail: gchenncem@gmail.com; Schmid, Andreas K. [NCEM, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Mascaraque, Arantzazu [Depto. Física de Materiales, Universidad Complutense de Madrid, 28040 Madrid (Spain); Unidad Asociada IQFR (CSIC) - UCM, 28040 Madrid (Spain); N' Diaye, Alpha T. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)
2015-06-15
Possible magnetic skyrmion device applications motivate the search for structures that extend the stability of skyrmion spin textures to ambient temperature. Here, we demonstrate an experimental approach to stabilize a room temperature skyrmion ground state in chiral magnetic films via exchange coupling across non-magnetic spacer layers. Using spin polarized low-energy electron microscopy to measure all three Cartesian components of the magnetization vector, we image the spin textures in Fe/Ni films. We show how tuning the thickness of a copper spacer layer between chiral Fe/Ni films and perpendicularly magnetized Ni layers permits stabilization of a chiral stripe phase, a skyrmion phase, and a single domain phase. This strategy to stabilize skyrmion ground states can be extended to other magnetic thin film systems and may be useful for designing skyrmion based spintronics devices.
Terahertz spectroscopy of ground state HD18O
Yu, Shanshan; Pearson, John C.; Drouin, Brian J.; Miller, Charles E.; Kobayashi, Kaori; Matsushima, Fusakazu
2016-10-01
Terahertz absorption spectroscopy was employed to measure the ground state pure rotational transitions of the water isotopologue HD18O . A total of 105 pure rotational transitions were observed in the 0.5-5.0 THz region with ∼ 100 kHz accuracy for the first time. The observed positions were fit to experimental accuracy using the Euler series expansion of the asymmetric-top Hamiltonian together with the literature Microwave, Far-IR and IR data in the ground state and ν2 . The new measurements and predictions reported here support the analysis of astronomical observations by high-resolution spectroscopic telescopes such as SOFIA and ALMA where laboratory rest frequencies with uncertainties of 1 MHz or less are required for proper analysis of velocity resolved astrophysical data.
Ground state solutions for non-local fractional Schrodinger equations
Directory of Open Access Journals (Sweden)
Yang Pu
2015-08-01
Full Text Available In this article, we study a time-independent fractional Schrodinger equation with non-local (regional diffusion $$ (-\\Delta^{\\alpha}_{\\rho}u + V(xu = f(x,u \\quad \\text{in }\\mathbb{R}^{N}, $$ where $\\alpha \\in (0,1$, $N > 2\\alpha$. We establish the existence of a non-negative ground state solution by variational methods.
0{sup +} ground state dominance in many-body systems
Energy Technology Data Exchange (ETDEWEB)
Zhao, Yu-Min [Southeast Univ., Dept. of Physics, Nanjing (China); Arima, Akito [The House of Councilors, Tokyo (Japan); Yoshinaga, Naotaka [Saitama Univ., Physics Dept., Saitama (Japan)
2002-12-01
We propose a simple approach to predict the angular momentum I ground states (Ig.s.) probabilities of many-body systems without diagonalization of the hamiltonian using random interactions. It is suggested that the 0g.s. dominance in boson systems and even valence nucleon systems is not given by the model space as previously assumed, but by specific two-body interactions. (author)
Detecting topological order in a ground state wave function
2005-01-01
A large class of topological orders can be understood and classified using the string-net condensation picture. These topological orders can be characterized by a set of data (N, d_i, F^{ijk}_{lmn}, \\delta_{ijk}). We describe a way to detect this kind of topological order using only the ground state wave function. The method involves computing a quantity called the ``topological entropy'' which directly measures the quantum dimension D = \\sum_i d^2_i.
Reduced M(atrix) theory models: ground state solutions
López, J L
2015-01-01
We propose a method to find exact ground state solutions to reduced models of the SU($N$) invariant matrix model arising from the quantization of the 11-dimensional supermembrane action in the light-cone gauge. We illustrate the method by applying it to lower dimensional toy models and for the SU(2) group. This approach could, in principle, be used to find ground state solutions to the complete 9-dimensional model and for any SU($N$) group. The Hamiltonian, the supercharges and the constraints related to the SU($2$) symmetry are built from operators that generate a multicomponent spinorial wave function. The procedure is based on representing the fermionic degrees of freedom by means of Dirac-like gamma matrices, as was already done in the first proposal of supersymmetric (SUSY) quantum cosmology. We exhibit a relation between these finite $N$ matrix theory ground state solutions and SUSY quantum cosmology wave functions giving a possible physical significance of the theory even for finite $N$.
Alternative ground states enable pathway switching in biological electron transfer
Abriata, Luciano A.; Álvarez-Paggi, Damián; Ledesma, Gabriela N.; Blackburn, Ninian J.; Vila, Alejandro J.; Murgida, Daniel H.
2012-01-01
Electron transfer is the simplest chemical reaction and constitutes the basis of a large variety of biological processes, such as photosynthesis and cellular respiration. Nature has evolved specific proteins and cofactors for these functions. The mechanisms optimizing biological electron transfer have been matter of intense debate, such as the role of the protein milieu between donor and acceptor sites. Here we propose a mechanism regulating long-range electron transfer in proteins. Specifically, we report a spectroscopic, electrochemical, and theoretical study on WT and single-mutant CuA redox centers from Thermus thermophilus, which shows that thermal fluctuations may populate two alternative ground-state electronic wave functions optimized for electron entry and exit, respectively, through two different and nearly perpendicular pathways. These findings suggest a unique role for alternative or “invisible” electronic ground states in directional electron transfer. Moreover, it is shown that this energy gap and, therefore, the equilibrium between ground states can be fine-tuned by minor perturbations, suggesting alternative ways through which protein–protein interactions and membrane potential may optimize and regulate electron–proton energy transduction. PMID:23054836
Nuclear ground-state masses and deformations: FRDM(2012)
Moller, P; Ichikawa, T; Sagawa, H
2015-01-01
We tabulate the atomic mass excesses and binding energies, ground-state shell-plus-pairing corrections, ground-state microscopic corrections, and nuclear ground-state deformations of 9318 nuclei ranging from $^{16}$O to $A=339$. The calculations are based on the finite-range droplet macroscopic model and the folded-Yukawa single-particle microscopic model. Relative to our FRDM(1992) mass table in {\\sc Atomic Data and Nuclear Data Tables} [{\\bf 59} 185 (1995)], the results are obtained in the same model, but with considerably improved treatment of deformation and fewer of the approximations that were necessary earlier, due to limitations in computer power. The more accurate execution of the model and the more extensive and more accurate experimental mass data base now available allows us to determine one additional macroscopic-model parameter, the density-symmetry coefficient $L$, which was not varied in the previous calculation, but set to zero. Because we now realize that the FRDM is inaccurate for some high...
One-Way Information Deficit and Geometry for a Class of Two-Qubit States
Institute of Scientific and Technical Information of China (English)
WANG Yao-Kun; MA Teng; LI Bo; WANG Zhi-Xi
2013-01-01
The work deficit,as introduced by Jonathan Oppenheim et al.[Phys.Rev.Lett.89 (2002) 180402]is a good measure of the quantum correlations in a state and provides a new standpoint for understanding quantum non-locality.In this paper,we analytically evaluate the one-way information deficit (OWID) for the Bell-diagonal states and a class of two-qubit states and further give the geometry picture for OWID.The dynamic behavior of the OWID under decoherence channel is investigated and it is shown that the OWID of some classes of X states is more robust against the decoherence than the entanglement.
Algebraic geometry tools for the study of entanglement: an application to spin squeezed states
Bernardi, Alessandra; Carusotto, Iacopo
2012-03-01
A short review of algebraic geometry tools for the decomposition of tensors and polynomials is given from the point of view of applications to quantum and atomic physics. Examples of application to assemblies of indistinguishable two-level bosonic atoms are discussed using modern formulations of the classical Sylvester algorithm for the decomposition of homogeneous polynomials in two variables. In particular, the symmetric rank and symmetric border rank of spin squeezed states are calculated as well as their Schrödinger-cat-like decomposition as the sum of macroscopically different coherent spin states; Fock states provide an example of states for which the symmetric rank and the symmetric border rank are different.
Coupled cluster calculations of ground and excited states of nuclei
Kowalski, K L; Hjorth-Jensen, M; Papenbrock, T; Piecuch, P
2004-01-01
The standard and renormalized coupled cluster methods with singles, doubles, and noniterative triples and their generalizations to excited states, based on the equation of motion coupled cluster approach, are applied to the He-4 and O-16 nuclei. A comparison of coupled cluster results with the results of the exact diagonalization of the Hamiltonian in the same model space shows that the quantum chemistry inspired coupled cluster approximations provide an excellent description of ground and excited states of nuclei. The bulk of the correlation effects is obtained at the coupled cluster singles and doubles level. Triples, treated noniteratively, provide the virtually exact description.
Ground states of fermionic lattice Hamiltonians with permutation symmetry
Kraus, Christina V.; Lewenstein, Maciej; Cirac, J. Ignacio
2013-08-01
We study the ground states of lattice Hamiltonians that are invariant under permutations, in the limit where the number of lattice sites N→∞. For spin systems, these are product states, a fact that follows directly from the quantum de Finetti theorem. For fermionic systems, however, the problem is very different, since mode operators acting on different sites do not commute, but anticommute. We construct a family of fermionic states, F, from which such ground states can be easily computed. They are characterized by few parameters whose number only depends on M, the number of modes per lattice site. We also give an explicit construction for M=1,2. In the first case, F is contained in the set of Gaussian states, whereas in the second it is not. Inspired by that construction, we build a set of fermionic variational wave functions, and apply it to the Fermi-Hubbard model in two spatial dimensions, obtaining results that go beyond the generalized Hartree-Fock theory.
Ground state energies from converging and diverging power series expansions
Lisowski, C.; Norris, S.; Pelphrey, R.; Stefanovich, E.; Su, Q.; Grobe, R.
2016-10-01
It is often assumed that bound states of quantum mechanical systems are intrinsically non-perturbative in nature and therefore any power series expansion methods should be inapplicable to predict the energies for attractive potentials. However, if the spatial domain of the Schrödinger Hamiltonian for attractive one-dimensional potentials is confined to a finite length L, the usual Rayleigh-Schrödinger perturbation theory can converge rapidly and is perfectly accurate in the weak-binding region where the ground state's spatial extension is comparable to L. Once the binding strength is so strong that the ground state's extension is less than L, the power expansion becomes divergent, consistent with the expectation that bound states are non-perturbative. However, we propose a new truncated Borel-like summation technique that can recover the bound state energy from the diverging sum. We also show that perturbation theory becomes divergent in the vicinity of an avoided-level crossing. Here the same numerical summation technique can be applied to reproduce the energies from the diverging perturbative sums.
On large amplitude motions of simplest amides in the ground and excited electronic states
Tukachev, N. V.; Bataev, V. A.; Godunov, I. A.
2016-12-01
For the formamide, acetamide, N-methylformamide and N-methylacetamide molecules in the ground (S0) and lowest excited singlet (S1) and triplet (T1) electronic states equilibrium geometry parameters, harmonic vibrational frequencies, barriers to conformational transitions and conformer energy differences were estimated by means of MP2, CCSD(T), CASSCF, CASPT2 and MRCI ab initio methods. One-, two- and three-dimensional potential energy surface (PES) sections corresponding to different large amplitude motions (LAM) were calculated by means of MP2/aug-cc-pVTZ (S0) and CASPT2/cc-pVTZ (S1,T1). For these molecules, in each excited electronic state six minima were found on 2D PES sections. Using PES sections, different anharmonic vibrational problems were solved and the frequencies of large amplitude vibrations were determined.
Continuous Vibrational Cooling of Ground State Rb2
Tallant, Jonathan; Marcassa, Luis
2014-05-01
The process of photoassociation generally results in a distribution of vibrational levels in the electronic ground state that is energetically close to the dissociation limit. Several schemes have appeared that aim to transfer the population from the higher vibrational levels to lower ones, especially the ground vibrational state. We demonstrate continuous production of vibrationally cooled Rb2 using optical pumping. The vibrationally cooled molecules are produced in three steps. First, we use a dedicated photoassociation laser to produce molecules in high vibrational levels of the X1Σg+ state. Second, a broadband fiber laser at 1071 nm is used to transfer the molecules to lower vibrational levels via optical pumping through the A1Σu+ state. This process transfers the molecules from vibrational levels around ν ~= 113 to a distribution of levels where ν superluminescent diode near 685 nm that has its frequency spectrum shaped. The resulting vibrational distributions are probed using resonance-enhanced multiphoton ionization with a pulsed dye laser near 670 nm. The results are presented and compared with theoretical simulations. This work was supported by Fapesp and INCT-IQ.
The Monge metric on the sphere and geometry of quantum states
Energy Technology Data Exchange (ETDEWEB)
Zyczkowski, Karol [Centrum Fizyki Teoretycznej, Polska Akademia Nauk, Warsaw (Poland); Instytut Fizyki im. Mariana Smoluchowskiego, Uniwersytet Jagiellonski, Cracow (Poland)). E-mail: karol@cft.edu.pl; Slomczynski, Wojciech [Instytut Matematyki, Uniwersytet Jagiellonski, Cracow (Poland)). E-mail: slomczyn@im.uj.edu.pl
2001-08-31
Topological and geometrical properties of the set of mixed quantum states in the N-dimensional Hilbert space are analysed. Assuming that the corresponding classical dynamics takes place on the sphere we use the vector SU(2) coherent states and the generalized Husimi distributions to define the Monge distance between two arbitrary density matrices. The Monge metric has a simple semiclassical interpretation and induces a non-trivial geometry. Among all pure states the distance from the maximally mixed state {rho}*, proportional to the identity matrix, admits the largest value for the coherent states, while the delocalized 'chaotic' states are close to {rho}*. This contrasts the geometry induced by the standard (trace, Hilbert-Schmidt or Bures) metrics, for which the distance from {rho}* is the same for all pure states. We discuss possible physical consequences including unitary time evolution and the process of decoherence. We introduce also a simplified Monge metric, defined in the space of pure quantum states and more suitable for numerical computation. (author)
Estimating the ground-state probability of a quantum simulation with product-state measurements
Directory of Open Access Journals (Sweden)
Bryce eYoshimura
2015-10-01
Full Text Available .One of the goals in quantum simulation is to adiabatically generate the ground state of a complicated Hamiltonian by starting with the ground state of a simple Hamiltonian and slowly evolving the system to the complicated one. If the evolution is adiabatic and the initial and final ground states are connected due to having the same symmetry, then the simulation will be successful. But in most experiments, adiabatic simulation is not possible because it would take too long, and the system has some level of diabatic excitation. In this work, we quantify the extent of the diabatic excitation even if we do not know {it a priori} what the complicated ground state is. Since many quantum simulator platforms, like trapped ions, can measure the probabilities to be in a product state, we describe techniques that can employ these simple measurements to estimate the probability of being in the ground state of the system after the diabatic evolution. These techniques do not require one to know any properties about the Hamiltonian itself, nor to calculate its eigenstate properties. All the information is derived by analyzing the product-state measurements as functions of time.
Steady-state and transient heat transfer through fins of complex geometry
Directory of Open Access Journals (Sweden)
Taler Dawid
2014-06-01
Full Text Available Various methods for steady-state and transient analysis of temperature distribution and efficiency of continuous-plate fins are presented. For a constant heat transfer coefficient over the fin surface, the plate fin can be divided into imaginary rectangular or hexangular fins. At first approximate methods for determining the steady-state fin efficiency like the method of equivalent circular fin and the sector method are discussed. When the fin geometry is complex, thus transient temperature distribution and fin efficiency can be determined using numerical methods. A numerical method for transient analysis of fins with complex geometry is developed. Transient temperature distributions in continuous fins attached to oval tubes is computed using the finite volume - finite element methods. The developed method can be used in the transient analysis of compact heat exchangers to calculate correctly the heat flow rate transferred from the finned tubes to the fluid.
Grofe, Adam; Qu, Zexing; Truhlar, Donald G; Li, Hui; Gao, Jiali
2017-03-14
We describe a diabatic-at-construction (DAC) strategy for defining diabatic states to determine the adiabatic ground and excited electronic states and their potential energy surfaces using the multistate density functional theory (MSDFT). The DAC approach differs in two fundamental ways from the adiabatic-to-diabatic (ATD) procedures that transform a set of preselected adiabatic electronic states to a new representation. (1) The DAC states are defined in the first computation step to form an active space, whose configuration interaction produces the adiabatic ground and excited states in the second step of MSDFT. Thus, they do not result from a similarity transformation of the adiabatic states as in the ATD procedure; they are the basis for producing the adiabatic states. The appropriateness and completeness of the DAC active space can be validated by comparison with experimental observables of the ground and excited states. (2) The DAC diabatic states are defined using the valence bond characters of the asymptotic dissociation limits of the adiabatic states of interest, and they are strictly maintained at all molecular geometries. Consequently, DAC diabatic states have specific and well-defined physical and chemical meanings that can be used for understanding the nature of the adiabatic states and their energetic components. Here we present results for the four lowest singlet states of LiH and compare them to a well-tested ATD diabatization method, namely the 3-fold way; the comparison reveals both similarities and differences between the ATD diabatic states and the orthogonalized DAC diabatic states. Furthermore, MSDFT can provide a quantitative description of the ground and excited states for LiH with multiple strongly and weakly avoided curve crossings spanning over 10 Å of interatomic separation.
Topological Many-Body States in Quantum Antiferromagnets via Fuzzy Super-Geometry
Hasebe, Kazuki
2013-01-01
Recent vigorous investigations of topological order have not only discovered new topological states of matter but also shed new light to "already known" topological states. One established example with topological order is the valence bond solid (VBS) states in quantum antiferromagnets. The VBS states are disordered spin liquids with no spontaneous symmetry breaking but most typically manifest topological order known as hidden string order on 1D chain. Interestingly, the VBS models are based on mathematics analogous to fuzzy geometry. We review applications of the mathematics of fuzzy super-geometry in the construction of supersymmetric versions of VBS (SVBS) states, and give a pedagogical introduction of SVBS models and their properties [arXiv:0809.4885, 1105.3529, 1210.0299]. As concrete examples, we present detail analysis of supersymmetric versions of SU(2) and SO(5) VBS states, i.e. UOSp(N|2) and UOSp(N|4) SVBS states whose mathematics are closely related to fuzzy two- and four-superspheres. The SVBS sta...
Hu, Weifeng; Chan, Garnet Kin-Lic
2015-07-14
We describe and extend the formalism of state-specific analytic density matrix renormalization group (DMRG) energy gradients, first used by Liu et al. [J. Chem. Theor. Comput. 2013, 9, 4462]. We introduce a DMRG wave function maximum overlap following technique to facilitate state-specific DMRG excited-state optimization. Using DMRG configuration interaction (DMRG-CI) gradients, we relax the low-lying singlet states of a series of trans-polyenes up to C20H22. Using the relaxed excited-state geometries, as well as correlation functions, we elucidate the exciton, soliton, and bimagnon ("single-fission") character of the excited states, and find evidence for a planar conical intersection.
Ultracold Heteronuclear Mixture of Ground and Excited State Atoms
Khramov, Alexander; Dowd, William; Roy, Richard; Makrides, Constantinos; Petrov, Alexander; Kotochigova, Svetlana; Gupta, Subhadeep
2014-01-01
We report on the realization of an ultracold mixture of lithium atoms in the ground state and ytterbium atoms in the excited metastable 3P2 state. Such a mixture can support broad magnetic Feshbach resonances which may be utilized for the production of ultracold molecules with an electronic spin degree of freedom, as well as novel Efimov trimers. We investigate the interaction properties of the mixture in the presence of an external magnetic field and find an upper limit for the background interspecies two-body inelastic decay coefficient of K'2 < 3e-12 cm^3/s for the 3P2 m_J=-1 substate. We calculate the dynamic polarizabilities of the Yb 3P2 magnetic substates for a range of wavelengths, and find good agreement with our measurements at 1064nm. Our calculations also allow the identification of magic frequencies where Yb ground and metastable states are identically trapped and the determination of the interspecies van der Waals coefficients.
Spatial competition of the ground states in 1111 iron pnictides
Lang, G.; Veyrat, L.; Gräfe, U.; Hammerath, F.; Paar, D.; Behr, G.; Wurmehl, S.; Grafe, H.-J.
2016-07-01
Using nuclear quadrupole resonance, the phase diagram of 1111 R FeAsO1 -xFx (R =La , Ce, Sm) iron pnictides is constructed as a function of the local charge distribution in the paramagnetic state, which features low-doping-like (LD-like) and high-doping-like (HD-like) regions. Compounds based on magnetic rare earths (Ce, Sm) display a unified behavior, and comparison with La-based compounds reveals the detrimental role of static iron 3 d magnetism on superconductivity, as well as a qualitatively different evolution of the latter at high doping. It is found that the LD-like regions fully account for the orthorhombicity of the system, and are thus the origin of any static iron magnetism. Orthorhombicity and static magnetism are not hindered by superconductivity but limited by dilution effects, in agreement with two-dimensional (2D) (respectively three-dimensional) nearest-neighbor square lattice site percolation when the rare earth is nonmagnetic (respectively magnetic). The LD-like regions are not intrinsically supportive of superconductivity, contrary to the HD-like regions, as evidenced by the well-defined Uemura relation between the superconducting transition temperature and the superfluid density when accounting for the proximity effect. This leads us to propose a complete description of the interplay of ground states in 1111 pnictides, where nanoscopic regions compete to establish the ground state through suppression of superconductivity by static magnetism, and extension of superconductivity by proximity effect.
Analytical Potential Energy Function for the Ground State X1∑+ of Lanthanum Monofluoride
Institute of Scientific and Technical Information of China (English)
CHEN Lin-Hong; SHANG Ren-Cheng
2003-01-01
The equilibrium geometry, harmonic frequency and bond dissociation energy of lanthanum monofluoride have been calculated using Density-Functional Theory (DFT), post-HF methods MP2 and CCSD(T) with the energyconsistent relativistic effective core potentials. The possible electronic state and reasonable dissociation limit of the ground state of LaF are determined based on atomic and molecular reaction statics. Potential energy curve scans for the ground state X 1∑+ have been performed at B3LYP and CCSD(T) levels, due to their better results of harmonic frequency and bond dissociation energy. We find that the potential energy calculated with CCSD(T) is about 0.6 eV larger than the bond dissociation energy, when the internuclear distance is as large as 0.8 nm. The problem that single-reference ab initio methods do not meet dissociation limit during calculations of lanthanide heavy-metal elements is analyzed. We propose the calculation scheme to derive the analytical Murrell-Sorbie potential energy function. Vibrotational spectroscopic constants Be, ωe, ωeχe, αe, βe, De and He obtained by the standard Dunham treatment coincide well with the results of rotational analyses on spectroscopic experiments.
Ground State Correlations and the Multiconfiguration Mixing Method
Pillet, N; Van Giai, N; Berger, J F; Giai, Nguyen Van
2004-01-01
We study the convergence properties of a truncation scheme in describing the ground state properties of a many-particle system of fermions. The model wave function is built within a multiconfiguration mixing approach where the many-body wave function is described as a superposition of multiparticle-multihole configurations constructed upon a Slater determinant. The convergence properties of physical quantities such as correlation energies and single-particle occupation probabilities in terms of the increasing number of particle-hole configurations are investigated for the case of an exactly solvable pairing hamiltonian.
Ground-state spin of {sup 59}Mn
Energy Technology Data Exchange (ETDEWEB)
Oinonen, M.; Koester, U.; Aeystoe, J. [CERN, Geneva (Switzerland). EP Div.; Fedoseyev, V.; Mishin, V. [Rossijskaya Akademiya Nauk, Troitsk (Russian Federation). Inst. Spektroskopii; Huikari, J.; Jokinen, A.; Nieminen, A.; Peraejaervi, K. [Jyvaeskylae Univ. (Finland). Dept. of Physics; Knipper, A.; Walter, G. [Institute de Recherches Subatomiques, 67 - Strasbourg (France)
2001-02-01
Beta-decay of {sup 59}Mn has been studied at PSB-ISOLDE, CERN. The intense and pure Mn beam was produced using the Resonance Ionization Laser Ion Source (RILIS). Based on the measured {beta}-decay rates the ground-state spin and parity are proposed to be J{sup {pi}} = 5/2{sup -}. This result is consistent with the systematic trend of the odd-A Mn nuclei and extends the systematics one step further towards the neutron drip line. (orig.)
Triaxiality near the 110Ru ground state from Coulomb excitation
Doherty, D. T.; Allmond, J. M.; Janssens, R. V. F.; Korten, W.; Zhu, S.; Zielińska, M.; Radford, D. C.; Ayangeakaa, A. D.; Bucher, B.; Batchelder, J. C.; Beausang, C. W.; Campbell, C.; Carpenter, M. P.; Cline, D.; Crawford, H. L.; David, H. M.; Delaroche, J. P.; Dickerson, C.; Fallon, P.; Galindo-Uribarri, A.; Kondev, F. G.; Harker, J. L.; Hayes, A. B.; Hendricks, M.; Humby, P.; Girod, M.; Gross, C. J.; Klintefjord, M.; Kolos, K.; Lane, G. J.; Lauritsen, T.; Libert, J.; Macchiavelli, A. O.; Napiorkowski, P. J.; Padilla-Rodal, E.; Pardo, R. C.; Reviol, W.; Sarantites, D. G.; Savard, G.; Seweryniak, D.; Srebrny, J.; Varner, R.; Vondrasek, R.; Wiens, A.; Wilson, E.; Wood, J. L.; Wu, C. Y.
2017-03-01
A multi-step Coulomb excitation measurement with the GRETINA and CHICO2 detector arrays was carried out with a 430-MeV beam of the neutron-rich 110Ru (t1/2 = 12 s) isotope produced at the CARIBU facility. This represents the first successful measurement following the post-acceleration of an unstable isotope of a refractory element. The reduced transition probabilities obtained for levels near the ground state provide strong evidence for a triaxial shape; a conclusion confirmed by comparisons with the results of beyond-mean-field and triaxial rotor model calculations.
Evidence for the ground-state resonance of 26O
Lunderberg, E; Kohley, Z; Attanayake, H; Baumann, T; Bazin, D; Christian, G; Divaratne, D; Grimes, S M; Haagsma, A; Finck, J E; Frank, N; Luther, B; Mosby, S; Nagy, T; Peaslee, G F; Schiller, A; Snyder, J; Spyrou, A; Strongman, M J; Thoennessen, M
2012-01-01
Evidence for the ground state of the neutron-unbound nucleus 26O was observed for the first time in the single proton-knockout reaction from a 82 MeV/u 27F beam. Neutrons were measured in coincidence with 24O fragments. 26O was determined to be unbound by 150+50-150 keV from the observation of low-energy neutrons. This result agrees with recent shell model calculations based on microscopic two- and three-nucleon forces.
First Observation of Ground State Dineutron Decay: Be16
Spyrou, A.; Kohley, Z.; Baumann, T.; Bazin, D.; Brown, B. A.; Christian, G.; Deyoung, P. A.; Finck, J. E.; Frank, N.; Lunderberg, E.; Mosby, S.; Peters, W. A.; Schiller, A.; Smith, J. K.; Snyder, J.; Strongman, M. J.; Thoennessen, M.; Volya, A.
2012-03-01
We report on the first observation of dineutron emission in the decay of Be16. A single-proton knockout reaction from a 53MeV/u B17 beam was used to populate the ground state of Be16. Be16 is bound with respect to the emission of one neutron and unbound to two-neutron emission. The dineutron character of the decay is evidenced by a small emission angle between the two neutrons. The two-neutron separation energy of Be16 was measured to be 1.35(10) MeV, in good agreement with shell model calculations, using standard interactions for this mass region.
Ground state of a confined Yukawa plasma including correlation effects
Henning, C; Filinov, A; Piel, A; Bonitz, M
2007-01-01
The ground state of an externally confined one-component Yukawa plasma is derived analytically using the local density approximation (LDA). In particular, the radial density profile is computed. The results are compared with the recently obtained mean-field (MF) density profile \\cite{henning.pre06}. While the MF results are more accurate for weak screening, LDA with correlations included yields the proper description for large screening. By comparison with first-principle simulations for three-dimensional spherical Yukawa crystals we demonstrate that both approximations complement each other. Together they accurately describe the density profile in the full range of screening parameters.
Tetraphenylhexaazaanthracenes: 16π Weakly Antiaromatic Species with Singlet Ground States.
Constantinides, Christos P; Zissimou, Georgia A; Berezin, Andrey A; Ioannou, Theodosia A; Manoli, Maria; Tsokkou, Demetra; Theodorou, Eleni; Hayes, Sophia C; Koutentis, Panayiotis A
2015-08-21
Tetraphenylhexaazaanthracene, TPHA-1, is a fluorescent zwitterionic biscyanine with a closed-shell singlet ground state. TPHA-1 overcomes its weak 16π antiaromaticity by partitioning its π system into 6π positive and 10π negative cyanines. The synthesis of TPHA-1 is low yielding and accompanied by two analogous TPHA isomers: the deep red, non-charge-separated, quinoidal TPHA-2, and the deep green TPHA-3 that partitions into two equal but oppositely charged 8π cyanines. The three TPHA isomers are compared.
Ground state hyperfine splitting of high Z hydrogenlike ions
Shabaev, V M; Kühl, T; Artemiev, A N; Yerokhin, V A
1997-01-01
The ground state hyperfine splitting values of high Z hydrogenlike ions are calculated. The relativistic, nuclear and QED corrections are taken into account. The nuclear magnetization distribution correction (the Bohr-Weisskopf effect) is evaluated within the single particle model with the g_{S}-factor chosen to yield the observed nuclear moment. An additional contribution caused by the nuclear spin-orbit interaction is included in the calculation of the Bohr-Weisskopf effect. It is found that the theoretical value of the wavelength of the transition between the hyperfine splitting components in ^{165}Ho^{66+} is in good agreement with experiment.
Photoabsorption by ground-state alkali-metal atoms.
Weisheit, J. C.
1972-01-01
Principal-series oscillator strengths and ground-state photoionization cross sections are computed for sodium, potassium, rubidium, and cesium. The degree of polarization of the photoelectrons is also predicted for each atom. The core-polarization correction to the dipole transition moment is included in all of the calculations, and the spin-orbit perturbation of valence-p-electron orbitals is included in the calculations of the Rb and Cs oscillator strengths and of all the photoionization cross sections. The results are compared with recent measurements.
Ground- and excited-state impurity bands in quantum wells
Ghazali, A.; Gold, A.; Serre, J.
1989-02-01
The density of states and the spectral density of electrons in quantum wells with charged impurities are calculated with use of a multiple-scattering method. The impurity-density-dependent broadening and the gradual merging of the ground (1s) and excited (2p+/-,2s) impurity levels into impurity bands are investigated. At low density the shapes of the 1s, 2p+/-, and 2s spectral densities are found to be in excellent agreement with the analytical results obtained for the ideal two-dimensional Coulomb problem.
Universal crossover from ground-state to excited-state quantum criticality
Kang, Byungmin; Potter, Andrew C.; Vasseur, Romain
2017-01-01
We study the nonequilibrium properties of a nonergodic random quantum chain in which highly excited eigenstates exhibit critical properties usually associated with quantum critical ground states. The ground state and excited states of this system belong to different universality classes, characterized by infinite-randomness quantum critical behavior. Using strong-disorder renormalization group techniques, we show that the crossover between the zero and finite energy density regimes is universal. We analytically derive a flow equation describing the unitary dynamics of this isolated system at finite energy density from which we obtain universal scaling functions along the crossover.
Uniqueness of ground states of some coupled nonlinear Schrodinger systems and their application
MA,LI; Lin ZHAO
2007-01-01
We establish the uniqueness of ground states of some coupled nonlinear Schrodinger systems in the whole space. We firstly use Schwartz symmetrization to obtain the existence of ground states for a more general case. To prove the uniqueness of ground states, we use the radial symmetry of the ground states to transform the systems into an ordinary differential system, and then we use the integral forms of the system. More interestingly, as an application of our uniqueness results, we derive a s...
Accretion disc geometry evolution of GRS 1915+105 during its plataeu states
Sarathi Pal, Partha; Gopal Dutta, Broja; Chakrabarti, Sandip Kumar
2016-07-01
The evolution of Time-lags are correlated with the accretion geometry during Plateau states of GRS 1915+105. We find that the lag spectrum for the χ_3 class is different from that of χ_1, χ_2 and χ_4 classes. Hard lags occur only when Comptonizing efficiency (CE) is about 0.9% for different plateau states and its evolution follows the sequence of class transitions suggested on the basis of CE parameter. We conclude that the variation of time lags could be due to change of size of the CENBOL which is often triggered by Compton cooling process.
State-space geometry, non-extremal black holes and Kaluza-Klein monopoles
Bellucci, Stefano
2012-01-01
We examine the statistical nature of the charged anticharged non-extremal black holes in string theory. From the perspective of the intrinsic Riemannian Geometry, the first principle of the statistical mechanics shows that the stability properties of general nonextremal nonlarge charged black brane solutions are divulged from the positivity of the corresponding principle minors of the space-state metric tensor. Under the addition of the Kaluza-Klein monopoles, a novel aspect of the Gaussian fluctuations demonstrates that the canonical fluctuations can be ascertained without any approximation. We offer the state-space geometric implication for the most general non-extremal black brane configurations in string theory.
Charge transfer to ground-state ions produces free electrons
You, D.; Fukuzawa, H.; Sakakibara, Y.; Takanashi, T.; Ito, Y.; Maliyar, G. G.; Motomura, K.; Nagaya, K.; Nishiyama, T.; Asa, K.; Sato, Y.; Saito, N.; Oura, M.; Schöffler, M.; Kastirke, G.; Hergenhahn, U.; Stumpf, V.; Gokhberg, K.; Kuleff, A. I.; Cederbaum, L. S.; Ueda, K.
2017-01-01
Inner-shell ionization of an isolated atom typically leads to Auger decay. In an environment, for example, a liquid or a van der Waals bonded system, this process will be modified, and becomes part of a complex cascade of relaxation steps. Understanding these steps is important, as they determine the production of slow electrons and singly charged radicals, the most abundant products in radiation chemistry. In this communication, we present experimental evidence for a so-far unobserved, but potentially very important step in such relaxation cascades: Multiply charged ionic states after Auger decay may partially be neutralized by electron transfer, simultaneously evoking the creation of a low-energy free electron (electron transfer-mediated decay). This process is effective even after Auger decay into the dicationic ground state. In our experiment, we observe the decay of Ne2+ produced after Ne 1s photoionization in Ne-Kr mixed clusters.
Charge transfer to ground-state ions produces free electrons
You, D.; Fukuzawa, H.; Sakakibara, Y.; Takanashi, T.; Ito, Y.; Maliyar, G. G.; Motomura, K.; Nagaya, K.; Nishiyama, T.; Asa, K.; Sato, Y.; Saito, N.; Oura, M.; Schöffler, M.; Kastirke, G.; Hergenhahn, U.; Stumpf, V.; Gokhberg, K.; Kuleff, A. I.; Cederbaum, L. S.; Ueda, K
2017-01-01
Inner-shell ionization of an isolated atom typically leads to Auger decay. In an environment, for example, a liquid or a van der Waals bonded system, this process will be modified, and becomes part of a complex cascade of relaxation steps. Understanding these steps is important, as they determine the production of slow electrons and singly charged radicals, the most abundant products in radiation chemistry. In this communication, we present experimental evidence for a so-far unobserved, but potentially very important step in such relaxation cascades: Multiply charged ionic states after Auger decay may partially be neutralized by electron transfer, simultaneously evoking the creation of a low-energy free electron (electron transfer-mediated decay). This process is effective even after Auger decay into the dicationic ground state. In our experiment, we observe the decay of Ne2+ produced after Ne 1s photoionization in Ne–Kr mixed clusters. PMID:28134238
Eigenvectors in the superintegrable model II: ground-state sector
Energy Technology Data Exchange (ETDEWEB)
Au-Yang, Helen; Perk, Jacques H H [Department of Physics, Oklahoma State University, 145 Physical Sciences, Stillwater, OK 74078-3072 (United States)], E-mail: helenperk@yahoo.com, E-mail: perk@okstate.edu
2009-09-18
In 1993, Baxter gave 2{sup m{sub Q}} eigenvalues of the transfer matrix of the N-state superintegrable chiral Potts model with the spin-translation quantum number Q, where m{sub Q} = lfloor(NL - L - Q)/Nrfloor. In our previous paper we studied the Q = 0 ground-state sector, when the size L of the transfer matrix is chosen to be a multiple of N. It was shown that the corresponding {tau}{sub 2} matrix has a degenerate eigenspace generated by the generators of r = m{sub 0} simple sl{sub 2} algebras. These results enable us to express the transfer matrix in the subspace in terms of these generators E{sup {+-}}{sub m} and H{sub m} for m = 1, ..., r. Moreover, the corresponding 2{sup r} eigenvectors of the transfer matrix are expressed in terms of rotated eigenvectors of H{sub m}.
Theoretical study on thermal decomposition of azoisobutyronitrile in ground state
Institute of Scientific and Technical Information of China (English)
SUN Chengke; ZHAO Hongmei; LI Zonghe
2004-01-01
The thermal decomposition mechanisms of azoisobutyronitrile (AIBN) in the ground state have been investigated systematically. Based on the potential energy surfaces (PES) of various possible dissociation paths obtained using the semiempirical AM1 method with partial optimization, the density function theory B3LYP/6-311G* method was employed to optimize the geometric parameters of the reactants, the intermediates, the products and the transition states,which were further confirmed by the vibrational analysis. The obtained results show that the reaction process of the two-bond (three-body) simultaneous cleavage Me2(CN)C-N=Nleading to the reaction proceeding in the former pathway. The calculation results were consistent with all the experimental facts.
Ground state structures and properties of Si3H ( = 1–6) clusters
Indian Academy of Sciences (India)
D Balamurugan; R Prasad
2003-01-01
The ground state structures and properties of Si3H (1 ≤ ≤ 6) clusters have been calculated using Car–Parrinello molecular dynamics with simulated annealing and steepest descent optimization methods. We have studied cohesive energy per particle and first excited electronic level gap of the clusters as a function of hydrogenation. Hydrogenation is done till all dangling bonds of silicon are saturated. Our results show that over coordination of hydrogen is favoured in Si3H clusters and the geometry of Si3 cluster does not change due to hydrogenation. Cohesive energy per particle and first excited electronic level gap study of the clusters show that Si3H6 cluster is most stable and Si3H3 cluster is most unstable among the clusters considered here.
Ground state for CH2 and symmetry for methane decomposition
Institute of Scientific and Technical Information of China (English)
Zhang Li; Luo Wen-Lang; Ruan Wen; Jiang Gang; Zhu Zheng-He
2008-01-01
Using the different level of methods B3P86, BLYP, B3PW91, HF, QCISD, CASSCF (4,4) and MP2 with the various basis functions 6-311G**, D95, cc-pVTZ and DGDZVP, the calculations of this paper confirm that the ground state is X3B1 with C2v group for CH2. Furthermore, the three kinds of theoretical methods, I.e. B3P86, CCSD(T, MP4) and G2 with the same basis set cc-pVTZ only are used to recalculate the zero-point energy revision which are modified by scaling factor 0.989 for the high level based on the virial theorem, and also with the correction for basis set superposition error. These results are also contrary to X3Σ-g for the ground state of CH2 in reference. Based on the atomic and molecular reaction statics, this paper proves that the decomposition type (1) I.e. CH4→CH2+H2, is forbidden and the decomposition type (2) I.e. CH4→CH3+H is allowed for CH4. This is similar to the decomposition of SiH4.
Ground-state electronic structure of actinide monocarbides and mononitrides
DEFF Research Database (Denmark)
Petit, Leon; Svane, Axel; Szotek, Z.
2009-01-01
The self-interaction corrected local spin-density approximation is used to investigate the ground-state valency configuration of the actinide ions in the actinide monocarbides, AC (A=U,Np,Pu,Am,Cm), and the actinide mononitrides, AN. The electronic structure is characterized by a gradually...... increasing degree of f electron localization from U to Cm, with the tendency toward localization being slightly stronger in the (more ionic) nitrides compared to the (more covalent) carbides. The itinerant band picture is found to be adequate for UC and acceptable for UN, while a more complex manifold...... of competing localized and delocalized f-electron configurations underlies the ground states of NpC, PuC, AmC, NpN, and PuN. The fully localized 5f-electron configuration is realized in CmC (f7), CmN (f7), and AmN (f6). The observed sudden increase in lattice parameter from PuN to AmN is found to be related...
Au42: A possible ground-state noble metallic nanotube
Wang, Jing; Ning, Hua; Ma, Qing-Min; Liu, Ying; Li, You-Cheng
2008-10-01
A large hollow tubelike Au42 is predicted as a new ground-state configuration based on the scalar relativistic density functional theory. The shape of this new Au42 cluster is similar to a (5,5) single-wall gold nanotube, the two ends of which are capped by half of a fullerenelike Au32. In the same way, a series of Aun (n =37,42,47,52,57,62,67,72,…, Δn =5) tubelike structures has been constructed. The highest occupied molecular orbital-lowest unoccupied molecular orbital gaps suggested a significant semiconductor-conductor alternation in n ɛ[32,47]. Similar to the predictions and speculation of Daedalus [D. E. H. Jones, New Sci. 32, 245 (1966); E. Osawa, Superaromaticity (Kagaku, Kyoto, 1970), Vol. 25, pp. 854-863; Z. Yoshida and E. Osawa, Aromaticity Chemical Monograph (Kagaku Dojin, Kyoto, Japan, 1971), Vol. 22, pp. 174-176; D. A. Bochvar and E. G. Gal'pern, Dokl. Akad. Nauk SSSR 209, 610 (1973)], here a large hollow ground-state gold nanotube was predicted theoretically.
On the nature of the oligoacene ground state
Hachmann, Johannes; Dorando, Jonathan; Aviles, Michael; Kin-Lic Chan, Garnet
2007-03-01
The nature of the oligoacene ground state - its spin, singlet-triplet gap, and diradical character as a function of chain-length - is a question of ongoing theoretical and experimental interest with notable technological implications. Previous computational studies have given inconclusive answers to this challenging electronic structure problem (see e.g. [1]). In the present study we exploit the capabilities of the local ab initio Density Matrix Renormalization Group (DMRG) [2], which allows the numerically exact (FCI) solution of the Schr"odinger equation in a chosen 1-particle basis and active space for quasi-one-dimensional systems. We compute the singlet-triplet gap from first principles as a function of system length ranging from naphthalene to tetradecacene, correlating the full π-space (i.e. up to 58 electrons in 58 orbitals) and converging the results to a few μEh accuracy [3]. In order to study the diradical nature of the oligoacene ground state we calculate expectation values over different diradical occupation and pair-correlation operators. Furthermore we study the natural orbitals and their occupation. [1] Bendikov, Duong, Starkey, Houk, Carter, Wudl, JACS 126 (2004), 7416. [2] Hachmann, Cardoen, Chan, JCP 125 (2006), 144101. [3] Hachmann, Dorando, Avil'es, Chan, in preparation.
Streamflow characteristics related to channel geometry of streams in western United States
Hedman, E.R.; Osterkamp, W.R.
1982-01-01
Assessment of surface-mining and reclamation activities generally requires extensive hydrologic data. Adequate streamflow data from instrumented gaging stations rarely are available, and estimates of surface- water discharge based on rainfall-runoff models, drainage area, and basin characteristics sometimes have proven unreliable. Channel-geometry measurements offer an alternative method of quickly and inexpensively estimating stream-flow characteristics for ungaged streams. The method uses the empirical development of equations to yield a discharge value from channel-geometry and channel-material data. The equations are developed by collecting data at numerous streamflow-gaging sites and statistically relating those data to selected discharge characteristics. Mean annual runoff and flood discharges with selected recurrence intervals can be estimated for perennial, intermittent, and ephemeral streams. The equations were developed from data collected in the western one-half of the conterminous United States. The effect of the channel-material and runoff characteristics are accounted for with the equations.
An integral equation-based numerical solver for Taylor states in toroidal geometries
O'Neil, Michael
2016-01-01
We develop an algorithm for the numerical calculation of Taylor states (also known as Beltrami, or force-free fields) in toroidal and toroidal-shell geometries using an analytical framework developed for the solution to the time-harmonic Maxwell equations. The scheme relies on the generalized Debye source representation of Maxwell fields and an integral representation of Beltrami fields which immediately yields a well-conditioned second-kind integral equation. This integral equation has a unique solution whenever the Beltrami parameter $\\lambda$ is not a member of a discrete, countable set of resonances which physically correspond to spontaneous symmetry breaking in the plasma. Several numerical examples relevant to magnetohydrodynamic equilibria calculations are provided. Lastly, our approach easily generalizes to arbitrary geometries, both bounded and unbounded, and of varying genus.
Ground state configurations in antiferromagnetic ultrathin films with dipolar anisotropy
Energy Technology Data Exchange (ETDEWEB)
Leon, H., E-mail: hleon@imre.oc.uh.cu [Instituto de Ciencia y Tecnologia de Materiales, Universidad de La Habana, Zapata e/ Mazon y G. Vedado, 10400 La Habana (Cuba)
2013-02-15
The formalism developed in a previous work to calculate the dipolar energy in quasi-two-dimensional crystals with ferromagnetic order is now extended to collinear antiferromagnetic order. Numerical calculations of the dipolar energy are carried out for systems with tetragonally distorted fcc [001] structures, the case of NiO and MnO ultrathin film grown in non-magnetic substrates, where the magnetic phase is a consequence of superexchange and dipolar interactions. The employed approximation allows to demonstrate that dipolar coupling between atomic layers is responsible for the orientation of the magnetization when it differs from the one in a single layer. The ground state energy of a given NiO or MnO film is found to depend not only on the strain, but also on how much the interlayer separation and the 2D lattice constant are changed with respect to the ideal values corresponding to the non-distorted cubic structure. Nevertheless, it is shown that the orientation of the magnetization in the magnetic phase of any of these films is determined by the strain exclusively. A striped phase with the magnetization along the [112{sup Macron }] direction appears as the ground state configuration of NiO and MnO ultrathin films. In films with equally oriented stripes along the layers this magnetic phase is twofold degenerate, while in films with multidomain layers it is eightfold degenerate. These results are not in contradiction with experimentally observed out-of-plane or in-plane magnetization of striped phases in NiO and MnO ultrathin films. - Highlights: Black-Right-Pointing-Pointer Dipolar energy in collinear antiferromagnetic ultrathin films is calculated. Black-Right-Pointing-Pointer Numerical results are presented for distorted fcc [001] structures. Black-Right-Pointing-Pointer The lowest energy of a system depends on how the tetragonal distortion is achieved. Black-Right-Pointing-Pointer A striped phase with magnetization in the [112{sup Macron }] direction is the
Energy Technology Data Exchange (ETDEWEB)
Delcey, Mickaël G. [Department of Chemistry – Ångström, The Theoretical Chemistry Programme, Uppsala University, Box 518, 751 20 Uppsala (Sweden); Freitag, Leon; González, Leticia, E-mail: leticia.gonzalez@univie.ac.at [Institut für Theoretische Chemie, Universität Wien, Währinger Straße 17, 1090 Vienna (Austria); Pedersen, Thomas Bondo [Centre for Theoretical and Computational Chemistry, Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, 0315 Oslo (Norway); Aquilante, Francesco [Department of Chemistry – Ångström, The Theoretical Chemistry Programme, Uppsala University, Box 518, 751 20 Uppsala (Sweden); Dipartimento di Chimica “G. Ciamician,” Università di Bologna, V. F. Selmi 2, 40126 Bologna (Italy); Lindh, Roland, E-mail: roland.lindh@kemi.uu.se [Department of Chemistry – Ångström, The Theoretical Chemistry Programme, Uppsala University, Box 518, 751 20 Uppsala (Sweden); Uppsala Center for Computational Chemistry - UC3, Uppsala University, Box 518, 751 20 Uppsala (Sweden)
2014-05-07
We present a formulation of analytical energy gradients at the complete active space self-consistent field (CASSCF) level of theory employing density fitting (DF) techniques to enable efficient geometry optimizations of large systems. As an example, the ground and lowest triplet state geometries of a ruthenium nitrosyl complex are computed at the DF-CASSCF level of theory and compared with structures obtained from density functional theory (DFT) using the B3LYP, BP86, and M06L functionals. The average deviation of all bond lengths compared to the crystal structure is 0.042 Å at the DF-CASSCF level of theory, which is slightly larger but still comparable with the deviations obtained by the tested DFT functionals, e.g., 0.032 Å with M06L. Specifically, the root-mean-square deviation between the DF-CASSCF and best DFT coordinates, delivered by BP86, is only 0.08 Å for S{sub 0} and 0.11 Å for T{sub 1}, indicating that the geometries are very similar. While keeping the mean energy gradient errors below 0.25%, the DF technique results in a 13-fold speedup compared to the conventional CASSCF geometry optimization algorithm. Additionally, we assess the singlet-triplet energy vertical and adiabatic differences with multiconfigurational second-order perturbation theory (CASPT2) using the DF-CASSCF and DFT optimized geometries. It is found that the vertical CASPT2 energies are relatively similar regardless of the geometry employed whereas the adiabatic singlet-triplet gaps are more sensitive to the chosen triplet geometry.
LABS problem and ground state spin glasses system
Leukhin, A. N.; Bezrodnyi, V. I.; Kozlova, Yu. A.
2016-12-01
In our work we demonstrate the new results of an exhaustive search for optimal binary sequences with minimum peak sidelobe (MPS) up to length N=85. The design problem for law autocorrelation binary sequences (LABS) is a notoriously difficult computational problem which is numbered as the problem number 005 in CSPLib. In statistical physics LABS problem can be interrepted as the energy of N iteracting Ising spins. This is a Bernasconi model. Due to this connection to physics we refer a binary sequence as one-dimensional spin lattice. At this assumption optimal binary sequences by merit factor (MF) criteria are the ground-state spin system without disorder which exhibits a glassy regime.
Ground state structures and properties of small hydrogenated silicon clusters
Indian Academy of Sciences (India)
R Prasad
2003-01-01
We present results for ground state structures and properties of small hydrogenated silicon clusters using the Car–Parrinello molecular dynamics with simulated annealing. We discuss the nature of bonding of hydrogen in these clusters. We find that hydrogen can form a bridge like Si–H–Si bond connecting two silicon atoms. We find that in the case of a compact and closed silicon cluster hydrogen bonds to the silicon cluster from outside. To understand the structural evolutions and properties of silicon cluster due to hydrogenation, we have studied the cohesive energy and first excited electronic level gap of clusters as a function of hydrogenation. We find that first excited electronic level gap of Si and SiH fluctuates as function of size and this may provide a first principle basis for the short-range potential fluctuations in hydrogenated amorphous silicon. The stability of hydrogenated silicon clusters is also discussed.
Ground-state correlations within a nonperturbative approach
De Gregorio, G.; Herko, J.; Knapp, F.; Lo Iudice, N.; Veselý, P.
2017-02-01
The contribution of the two-phonon configurations to the ground state of 4He and 16O is evaluated nonperturbatively using a Hartree-Fock basis within an equation-of-motion phonon method using a nucleon-nucleon optimized chiral potential. Convergence properties of energies and root-mean-square radii versus the harmonic oscillator frequency and space dimensions are investigated. The comparison with the second-order perturbation theory calculations shows that the higher-order terms have an appreciable repulsive effect and yield too-small binding energies and nuclear radii. It is argued that four-phonon configurations, through their strong coupling to two phonons, may provide most of the attractive contribution necessary for filling the gap between theoretical and experimental quantities. Possible strategies for accomplishing such a challenging task are discussed.
Sympathetic cooling of molecular ion motion to the ground state
Rugango, Rene; Dixon, Thomas H; Gray, John M; Khanyile, Ncamiso; Shu, Gang; Clark, Robert J; Brown, Kenneth R
2014-01-01
We demonstrate sympathetic sideband cooling of a $^{40}$CaH$^{+}$ molecular ion co-trapped with a $^{40}$Ca$^{+}$ atomic ion in a linear Paul trap. Both axial modes of the two-ion chain are simultaneously cooled to near the ground state of motion. The center of mass mode is cooled to an average quanta of harmonic motion $\\overline{n}_{\\mathrm{COM}} = 0.13 \\pm 0.03$, corresponding to a temperature of $12.47 \\pm 0.03 ~\\mu$K. The breathing mode is cooled to $\\overline{n}_{\\mathrm{BM}} = 0.05 \\pm 0.02$, corresponding to a temperature of $15.36 \\pm 0.01~\\mu$K.
Ground-state properties of neutron magic nuclei
Energy Technology Data Exchange (ETDEWEB)
Saxena, G., E-mail: gauravphy@gmail.com [Govt. Women Engineering College, Department of Physics (India); Kaushik, M. [Shankara Institute of Technology, Department of Physics (India)
2017-03-15
A systematic study of the ground-state properties of the entire chains of even–even neutron magic nuclei represented by isotones of traditional neutron magic numbers N = 8, 20, 40, 50, 82, and 126 has been carried out using relativistic mean-field plus Bardeen–Cooper–Schrieffer approach. Our present investigation includes deformation, binding energy, two-proton separation energy, single-particle energy, rms radii along with proton and neutron density profiles, etc. Several of these results are compared with the results calculated using nonrelativistic approach (Skyrme–Hartree–Fock method) along with available experimental data and indeed they are found with excellent agreement. In addition, the possible locations of the proton and neutron drip-lines, the (Z, N) values for the new shell closures, disappearance of traditional shell closures as suggested by the detailed analyzes of results are also discussed in detail.
Parusel, A. B.; Pohorille, A.
2001-01-01
The electronic ground and first excited states of retinal and its Schiff base are optimized for the first time using the semiempirical AM1 Hamiltonian. The barrier for rotation about the C(11)-C(12) double bond is characterized by variation of both the twist angle delta(C(10)-C(11)-C(12)-C(13)) and the bond length d(C(11)-C(12)). The potential energy surface is obtained by varying these two parameters. The calculated ground state rotational barrier is equal to 15.6 kcal/mol for retinal and 20.5 kcal/mol for its Schiff base. The all-trans conformation is more stable by 3.7 kcal/mol than the 11-cis geometry. For the first excited state, S(1,) the 90 degrees twisted geometry represents a saddle point for retinal with the rotational barrier of 14.6 kcal/mol. In contrast, this conformation is an energy minimum for the Schiff base. It can be easily reached at room temperature from the planar minima since it is separated from them by a barrier of only 0.6 kcal/mol. The 90 degrees minimum conformation is more stable than the all-trans by 8.6 kcal/mol. We are thus able to present a reaction path on the S(1) surface of the retinal Schiff base with an almost barrier-less geometrical relaxation into a twisted minimum geometry, as observed experimentally. The character of the ground and first excited singlet states underscores the need for the inclusion of double excitations in the calculations.
Martinetti, Pierre; Tomassini, Luca
2013-10-01
We study the metric aspect of the Moyal plane from Connes' noncommutative geometry point of view. First, we compute Connes' spectral distance associated with the natural isometric action of on the algebra of the Moyal plane . We show that the distance between any state of and any of its translated states is precisely the amplitude of the translation. As a consequence, we obtain the spectral distance between coherent states of the quantum harmonic oscillator as the Euclidean distance on the plane. We investigate the classical limit, showing that the set of coherent states equipped with Connes' spectral distance tends towards the Euclidean plane as the parameter of deformation goes to zero. The extension of these results to the action of the symplectic group is also discussed, with particular emphasis on the orbits of coherent states under rotations. Second, we compute the spectral distance in the double Moyal plane, intended as the product of (the minimal unitization of) by . We show that on the set of states obtained by translation of an arbitrary state of , this distance is given by the Pythagoras theorem. On the way, we prove some Pythagoras inequalities for the product of arbitrary unital and non-degenerate spectral triples. Applied to the Doplicher- Fredenhagen-Roberts model of quantum spacetime [DFR], these two theorems show that Connes' spectral distance and the DFR quantum length coincide on the set of states of optimal localization.
Competing ν = 5/2 fractional quantum Hall states in confined geometry
Fu, Hailong; Wang, Pengjie; Shan, Pujia; Xiong, Lin; Pfeiffer, Loren N.; West, Ken; Kastner, Marc A.; Lin, Xi
2016-11-01
Some theories predict that the filling factor 5/2 fractional quantum Hall state can exhibit non-Abelian statistics, which makes it a candidate for fault-tolerant topological quantum computation. Although the non-Abelian Pfaffian state and its particle-hole conjugate, the anti-Pfaffian state, are the most plausible wave functions for the 5/2 state, there are a number of alternatives with either Abelian or non-Abelian statistics. Recent experiments suggest that the tunneling exponents are more consistent with an Abelian state rather than a non-Abelian state. Here, we present edge-current-tunneling experiments in geometrically confined quantum point contacts, which indicate that Abelian and non-Abelian states compete at filling factor 5/2. Our results are consistent with a transition from an Abelian state to a non-Abelian state in a single quantum point contact when the confinement is tuned. Our observation suggests that there is an intrinsic non-Abelian 5/2 ground state but that the appropriate confinement is necessary to maintain it. This observation is important not only for understanding the physics of the 5/2 state but also for the design of future topological quantum computation devices.
Competing ν = 5/2 fractional quantum Hall states in confined geometry.
Fu, Hailong; Wang, Pengjie; Shan, Pujia; Xiong, Lin; Pfeiffer, Loren N; West, Ken; Kastner, Marc A; Lin, Xi
2016-11-01
Some theories predict that the filling factor 5/2 fractional quantum Hall state can exhibit non-Abelian statistics, which makes it a candidate for fault-tolerant topological quantum computation. Although the non-Abelian Pfaffian state and its particle-hole conjugate, the anti-Pfaffian state, are the most plausible wave functions for the 5/2 state, there are a number of alternatives with either Abelian or non-Abelian statistics. Recent experiments suggest that the tunneling exponents are more consistent with an Abelian state rather than a non-Abelian state. Here, we present edge-current-tunneling experiments in geometrically confined quantum point contacts, which indicate that Abelian and non-Abelian states compete at filling factor 5/2. Our results are consistent with a transition from an Abelian state to a non-Abelian state in a single quantum point contact when the confinement is tuned. Our observation suggests that there is an intrinsic non-Abelian 5/2 ground state but that the appropriate confinement is necessary to maintain it. This observation is important not only for understanding the physics of the 5/2 state but also for the design of future topological quantum computation devices.
Ground States and Excited States in a Tunable Graphene Quantum Dot
Institute of Scientific and Technical Information of China (English)
WANG Lin-Jun; CAO Gang; TU Tao; LI Hai-Ou; ZHOU Cheng; HAO Xiao-Jie; GUO Guang-Can; GUO Guo-Ping
2011-01-01
We prepare an etched gate tunable quantum dot in single-layer graphene and present transport measurement in this system. We extract the information of the ground states and excited states of the graphene quantum dot, as denoted by the presence of characteristic Coulomb blockade diamond diagrams. The results demonstrate that the quantum dot in single-layer graphene bodes well in future quantum transport study and quantum computing applications.%@@ We prepare an etched gate tunable quantum dot in single-layer graphene and present transport measurement in this system.We extract the information of the ground states and excited states of the graphene quantum dot, as denoted by the presence of characteristic Coulomb blockade diamond diagrams.The results demonstrate that the quantum dot in single-layer graphene bodes well in future quantum transport study and quantum computing applications.
DEFF Research Database (Denmark)
Reynisson, J.; Wilbrandt, R.; Brinck, V.
2002-01-01
of the long wavelength absorption band. A strong fluorescence is observed at 520 nm (tau(n) = 14.6 ns, phi(n) = 0.12 in deaerated acetonitrile). The fluorescence is quenched by 10 aromatic electron donors predominantly via a dynamic charge transfer mechanism, but ground state complexation is shown...
Institute of Scientific and Technical Information of China (English)
Zeng Hui; Zhao Jun
2012-01-01
In this paper,the energy,equilibrium geometry,and harmonic frequency of the ground electronic state of PO2 are computed using the B3LYP,B3P86,CCSD(T),and QCISD(T) methods in conjunction with the 6-311++G(3df,3pd) and cc-pVTZ basis sets.A comparison between the computational results and the experimental values indicates that the B3P86/6-311++G(3df,3pd) method can give better energy calculation results for the PO2 molecule.It is shown that the ground state of the PO2 molecule has C2v symmetry and its ground electronic state is X2A1.The equilibrium parameters of the structure are Rp-O =0.1465 nm,∠OPO =134.96°,and the dissociation energy is Ed =19.218 eV.The bent vibrational frequency v1 =386 cm-1,symmetric stretching frequency v2 =1095 cm-1,and asymmetric stretching frequency v3 =1333 cm-1 are obtained.On the basis of atomic and molecular reaction statics,a reasonable dissociation limit for the ground state of the PO2 molecule is determined.Then the analytic potential energy function of the PO2 molecule is derived using many-body expansion theory.The potential curves correctly reproduce the configurations and the dissociation energy for the PO2 molecule.
Lee, Myeong H; Geva, Eitan; Dunietz, Barry D
2016-05-19
The dependence of charge-transfer states on interfacial geometry at the phthalocyanine/fullerene organic photovoltaic system is investigated. The effect of deviations from the equilibrium geometry of the donor-donor-acceptor trimer on the energies of and electronic coupling between different types of interfacial electronic excited states is calculated from first-principles. Deviations from the equilibrium geometry are found to destabilize the donor-to-donor charge transfer states and to weaken their coupling to the photoexcited donor-localized states, thereby reducing their ability to serve as charge traps. At the same time, we find that the energies of donor-to-acceptor charge transfer states and their coupling to the donor-localized photoexcited states are either less sensitive to the interfacial geometry or become more favorable due to modifications relative to the equilibrium geometry, thereby enhancing their ability to serve as gateway states for charge separation. Through these findings, we eludicate how interfacial geometry modifications can play a key role in achieving charge separation in this widely studied organic photovoltaic system.
Ground and excited electronic state analysis of PrF²⁺ and PmF²⁺.
Schoendorff, George; Chi, Benjamin; Ajieren, Hans; Wilson, Angela K
2015-03-05
The ground state and excited state manifolds are computed for PrF(2+) and PmF(2+) at the CASSCF (n,8) level of theory where the active space spans the Ln 4f orbitals as well as the F 2pz orbital. Dynamical correlation is included using second-order multireference quasidegenerate perturbation theory (MCQDPT2). The spin-orbit multiplets for each of the excited states are resolved, and spin-orbit coupling constants are computed using the Breit-Pauli spin-orbit operator. Equilibrium geometries for each of the ground and excited states are computed, and the nature of the Ln-F bond is examined. Potential energy curves for the lowest four triplet states and lowest two quintet states are computed for PrF(2+), which split into 14 levels upon application of the spin-orbit Hamiltonian. Likewise, the lowest six quintet states are computed for PmF(2+) as well as the lowest triplet state and the lowest two septet states. These nine states split into 43 terms upon application of the spin-orbit Hamiltonian.
Gamiz-Hernandez, Ana P; Magomedov, Artiom; Hummer, Gerhard; Kaila, Ville R I
2015-02-12
Proton-coupled electron transfer (PCET) processes are elementary chemical reactions involved in a broad range of radical and redox reactions. Elucidating fundamental PCET reaction mechanisms are thus of central importance for chemical and biochemical research. Here we use quantum chemical density functional theory (DFT), time-dependent density functional theory (TDDFT), and the algebraic diagrammatic-construction through second-order (ADC(2)) to study the mechanism, thermodynamic driving force effects, and reaction barriers of both ground state proton transfer (pT) and photoinduced proton-coupled electron transfer (PCET) between nitrosylated phenyl-phenol compounds and hydrogen-bonded t-butylamine as an external base. We show that the obtained reaction barriers for the ground state pT reactions depend linearly on the thermodynamic driving force, with a Brønsted slope of 1 or 0. Photoexcitation leads to a PCET reaction, for which we find that the excited state reaction barrier depends on the thermodynamic driving force with a Brønsted slope of 1/2. To support the mechanistic picture arising from the static potential energy surfaces, we perform additional molecular dynamics simulations on the excited state energy surface, in which we observe a spontaneous PCET between the donor and the acceptor groups. Our findings suggest that a Brønsted analysis may distinguish the ground state pT and excited state PCET processes.
State estimators for tracking sharply-maneuvering ground targets
Visina, Radu S.; Bar-Shalom, Yaakov; Willett, Peter
2017-05-01
This paper presents an algorithm, based on the Interacting Multiple Model Estimator, that can be used to track the state of kinematic point targets, moving in two dimensions, that are capable of making sharp heading maneuvers over short periods of time, such as certain ground vehicles moving in an open field. The targets are capable of up to 60 °/s turn rates, while polar measurements are received at 1 Hz. We introduce the Non-Zero Mean, White Noise Turn-Rate IMM (IMM-WNTR) that consists of 3 modes based on a White Noise Turn Rate (WNTR) kinematic model that contains additive, white, Gaussian turn rate process noises. Two of the modes are considered maneuvering modes, and they have opposite (left/right), non-zero mean turn rate input noise. The need for non-zero mean turn rate process noise is explained, and Monte Carlo simulations compare this novel design to the traditional (single-mode) White Noise Acceleration Kalman Filter (WNA KF) and the two-mode White Noise Acceleration/Nearly-Coordinated Turn Rate IMM (IMM-CT). Results show that the IMM-WNTR filter achieves better accuracy and real-time consistency between expected error and actual error as compared to the (single-mode) WNA KF and the IMM-CT in all simulated scenarios, making it a very accurate state estimator for targets with sharp coordinated turn capability in 2D.
Zero-Point Fluctuations in the Nuclear Born-Oppenheimer Ground State
Zettili, Nouredine
The small-amplitude oscillations of rigid nuclei around the equilibrium state are described by means of the nuclear Born-Oppenheimer (NBO) method. In this limit, the method is shown to give back the random phase approximation (RPA) equations of motion. The contribution of the zero-point fluctuations to the ground state are examined, and the NBO ground state energy derived is shown to be identical to the RPA ground state energy.
Geometry of the set of mixed quantum states: An apophatic approach
Bengtsson, Ingemar; Życzkowski, Karol
2011-01-01
The set of quantum states consists of density matrices of order $N$, which are hermitian, positive and normalized by the trace condition. We analyze the structure of this set in the framework of the Euclidean geometry naturally arising in the space of hermitian matrices. For N=2 this set is the Bloch ball, embedded in $\\mathbbm R^3$. For $N \\ge 3$ this set of dimensionality $N^2-1$ has a much richer structure. We study its properties and at first advocate an apophatic approach, which concentrates on characteristics not possessed by this set. We also apply more constructive techniques and analyze two dimensional cross-sections and projections of the set of quantum states. They are dual to each other. At the end we make some remarks on certain dimension dependent properties.
Adiabatic corrections to holographic entanglement in thermofield doubles and confining ground states
Marolf, Donald
2016-01-01
We study entanglement in states of holographic CFTs defined by Euclidean path integrals over geometries with slowly varying metrics. In particular, our CFT spacetimes have $S^1$ fibers whose size $b$ varies along one direction ($x$) of an ${\\mathbb R}^{d-1}$ base. Such examples respect an ${\\mathbb R}^{d-2}$ Euclidean symmetry. Treating the $S^1$ direction as time leads to a thermofield double state on a spacetime with adiabatically varying redshift, while treating another direction as time leads to a confining ground state with slowly varying confinement scale. In both contexts the entropy of slab-shaped regions defined by $|x - x_0| \\le L$ exhibits well-known phase transitions at length scales $L= L_{crit}$ characterizing the CFT entanglements. For the thermofield double, the numerical coefficients governing the effect of variations in $b(x)$ on the transition are surprisingly small and exhibit an interesting change of sign: gradients reduce $L_{crit}$ for $d \\le 3$ but increase $L_{crit}$ for $d\\ge4$. This...
Hara, Akito; Awano, Teruyoshi
2017-06-01
Ultrashallow thermal donors (USTDs), which consist of light element impurities such as carbon, hydrogen, and oxygen, have been found in Czochralski silicon (CZ Si) crystals. To the best of our knowledge, these are the shallowest hydrogen-like donors with negative central-cell corrections in Si. We observed the ground-state splitting of USTDs by far-infrared optical absorption at different temperatures. The upper ground-state levels are approximately 4 meV higher than the ground-state levels. This energy level splitting is also consistent with that obtained by thermal excitation from the ground state to the upper ground state. This is direct evidence that the wave function of the USTD ground state is made up of a linear combination of conduction band minimums.
Resonance Raman Spectroscopic and Theoretical Study of Geometry Distortion of Thiourea in 21A State
Institute of Scientific and Technical Information of China (English)
Hai-bo Zhang; Yan-ying Zhao; Xu-ming Zheng
2012-01-01
The A-band resonance Raman spectra of thiourea were obtained in water and acetonitrile solution.B3LYP/6-311++G(3df,3pd) and RCIS/6-311++G(3df,3pd) calculations were done to elucidate the ultraviolet electronic transitions,the distorted geometry structure and the saddle point of thiourea in 21A excited state,respectively.The resonance Raman spectra were assigned.The absorption spectrum and resonance Raman intensities were modeled using Heller's time-dependent wavepacket approach to resonance Raman scattering.The results indicate that largest change in the displacement takes place with the C=S stretch mode v6 (|Δ|=0.95) and noticeable changes appear in the HsN3H6+H8N4H7 wag v5 (|Δ|=0.19),NCN symmetric stretch+C=S stretch+N3H6+H8N4 wag v4 (|Δ|=0.18),while the moderate intensities of 2v15 and 4v15 are mostly due to the large excited state frequency changes of v15,but not due to its significant change in the normal mode displacement.The mechanism of the appearance of even overtones of the S=CN2 out of plane deformation is explored.The results indicate that a Franck-Condon region saddle point is the driving force for the quadric phonon mechanism within the standard A-term of resonance Raman scattering,which leads to the pyramidalization of the carbon center and the geometry distortion of thiourea molecule in 21A excited state.
Ground-state properties of neutron-rich Mg isotopes
Watanabe, Shin; Shimada, Mitsuhiro; Tagami, Shingo; Kimura, Masaaki; Takechi, Maya; Fukuda, Mitsunori; Nishimura, Daiki; Suzuki, Takeshi; Matsumoto, Takuma; Shimizu, Yoshifumi R; Yahiro, Masanobu
2014-01-01
We analyze recently-measured total reaction cross sections for 24-38Mg isotopes incident on 12C targets at 240 MeV/nucleon by using the folding model and antisymmetrized molecular dynamics(AMD). The folding model well reproduces the measured reaction cross sections, when the projectile densities are evaluated by the deformed Woods-Saxon (def-WS) model with AMD deformation. Matter radii of 24-38Mg are then deduced from the measured reaction cross sections by ?ne-tuning the parameters of the def-WS model. The deduced matter radii are largely enhanced by nuclear deformation. Fully-microscopic AMD calculations with no free parameter well reproduce the deduced matter radii for 24-36Mg, but still considerably underestimate them for 37,38Mg. The large matter radii suggest that 37,38Mg are candidates for deformed halo nucleus. AMD also reproduces other existing measured ground-state properties (spin-parity, total binding energy, and one-neutron separation energy) of Mg isotopes. Neutron-number (N) dependence of defor...
Local reversibility and entanglement structure of many-body ground states
Kuwahara, Tomotaka; Amico, Luigi; Vedral, Vlatko
2015-01-01
The low-temperature physics of quantum many-body systems is largely governed by the structure of their ground states. Minimizing the energy of local interactions, ground states often reflect strong properties of locality such as the area law for entanglement entropy and the exponential decay of correlations between spatially separated observables. In this letter we present a novel characterization of locality in quantum states, which we call `local reversibility'. It characterizes the type of operations that are needed to reverse the action of a general disturbance on the state. We prove that unique ground states of gapped local Hamiltonian are locally reversible. This way, we identify new fundamental features of many-body ground states, which cannot be derived from the aforementioned properties. We use local reversibility to distinguish between states enjoying microscopic and macroscopic quantum phenomena. To demonstrate the potential of our approach, we prove specific properties of ground states, which are ...
The physics of solid-state neutron detector materials and geometries.
Caruso, A N
2010-11-10
Detection of neutrons, at high total efficiency, with greater resolution in kinetic energy, time and/or real-space position, is fundamental to the advance of subfields within nuclear medicine, high-energy physics, non-proliferation of special nuclear materials, astrophysics, structural biology and chemistry, magnetism and nuclear energy. Clever indirect-conversion geometries, interaction/transport calculations and modern processing methods for silicon and gallium arsenide allow for the realization of moderate- to high-efficiency neutron detectors as a result of low defect concentrations, tuned reaction product ranges, enhanced effective omnidirectional cross sections and reduced electron-hole pair recombination from more physically abrupt and electronically engineered interfaces. Conversely, semiconductors with high neutron cross sections and unique transduction mechanisms capable of achieving very high total efficiency are gaining greater recognition despite the relative immaturity of their growth, lithographic processing and electronic structure understanding. This review focuses on advances and challenges in charged-particle-based device geometries, materials and associated mechanisms for direct and indirect transduction of thermal to fast neutrons within the context of application. Calorimetry- and radioluminescence-based intermediate processes in the solid state are not included.
Ground state properties of a Bose-Einstein condensate confined in an anharmonic external potential
Institute of Scientific and Technical Information of China (English)
Wang Deng-Long; Yan Xiao-Hong; Tang Yi
2004-01-01
In light of the interference experiment of Bose-Einstein condensates, we present an anharmonic external potential model to study ground state properties of Bose-Einstein condensates. The ground state energy and the chemical potential have been analytically obtained, which are lower than those in harmonic trap. Additionally, it is found that the anharmonic strength of the external potential has an important effect on density and velocity distributions of the ground state for the Thomas-Fermi model.
Upper Bounds on the Degeneracy of the Ground State in Quantum Field Models
Directory of Open Access Journals (Sweden)
Asao Arai
2016-01-01
Full Text Available Axiomatic abstract formulations are presented to derive upper bounds on the degeneracy of the ground state in quantum field models including massless ones. In particular, given is a sufficient condition under which the degeneracy of the ground state of the perturbed Hamiltonian is less than or equal to the degeneracy of the ground state of the unperturbed one. Applications of the abstract theory to models in quantum field theory are outlined.
Exact many-electron ground states on diamond and triangle Hubbard chains
2008-01-01
We construct exact ground states of interacting electrons on triangle and diamond Hubbard chains. The construction requires (i) a rewriting of the Hamiltonian into positive semidefinite form, (ii) the construction of a many-electron ground state of this Hamiltonian, and (iii) the proof of the uniqueness of the ground state. This approach works in any dimension, requires no integrability of the model, and only demands sufficiently many microscopic parameters in the Hamiltonian which have to fu...
Lower bounds for the ground-state degeneracies of frustrated systems on fractal lattices
Curado; Nobre
2000-12-01
The total number of ground states for nearest-neighbor-interaction Ising systems with frustrations, defined on hierarchical lattices, is investigated. A simple method is presented, which allows one to factorize the ground-state degeneracy, at a given hierarchy level n, in terms of contributions due to all hierarchy levels. Such a method may yield the exact ground-state degeneracy of uniformly frustrated systems, whereas it works as an approximation for randomly frustrated models. In the latter cases, it is demonstrated that such an approximation yields lower-bound estimates for the ground-state degeneracies.
Ground-State Analysis for an Exactly Solvable Coupled-Spin Hamiltonian
Directory of Open Access Journals (Sweden)
Eduardo Mattei
2013-11-01
Full Text Available We introduce a Hamiltonian for two interacting su(2 spins. We use a mean-field analysis and exact Bethe ansatz results to investigate the ground-state properties of the system in the classical limit, defined as the limit of infinite spin (or highest weight. Complementary insights are provided through investigation of the energy gap, ground-state fidelity, and ground-state entanglement, which are numerically computed for particular parameter values. Despite the simplicity of the model, a rich array of ground-state features are uncovered. Finally, we discuss how this model may be seen as an analogue of the exactly solvable p+ip pairing Hamiltonian.
Ground state solutions for asymptotically periodic Schrodinger equations with critical growth
Directory of Open Access Journals (Sweden)
Hui Zhang
2013-10-01
Full Text Available Using the Nehari manifold and the concentration compactness principle, we study the existence of ground state solutions for asymptotically periodic Schrodinger equations with critical growth.
Spontaneous fission half-lives of heavy nuclei in ground state and in isomeric state
Ren, Zhongzhou; Xu, Chang
2005-09-01
We generalize the formulas of spontaneous fission half-lives of even-even nuclei in their ground state to both the case of odd nuclei and the case of fission isomers [Phys. Rev. C 71 (2005) 014309]. The spontaneous fission half-lives of odd- A nuclei and of odd-odd nuclei in the ground state are calculated by Swiatecki's formula, by its generalized form, and by a new formula where the blocking effect of unpaired nucleon on the half-lives has been taken into account with different mechanisms. By introducing a blocking factor or a generalized seniority in the formulas of the half-lives of even-even nuclei, we can reasonably reproduce the experimental fission half-lives of odd- A nuclei and of odd-odd nuclei with the same parameters used in ground state of even-even nuclei. For spontaneous fission of the isomers in transuranium nuclei the new formula can be simplified into a three-parameter formula and the isomeric half-lives can be well reproduced by the formula. The new formula of the isomeric half-lives is as good as Metag's formula of fission isomers. The half-lives of isomers from these formulas are very accurate and therefore these formulas can give reliable predictions for half-lives of new isomers of neighboring nuclei.
Derivation of novel human ground state naive pluripotent stem cells.
Gafni, Ohad; Weinberger, Leehee; Mansour, Abed AlFatah; Manor, Yair S; Chomsky, Elad; Ben-Yosef, Dalit; Kalma, Yael; Viukov, Sergey; Maza, Itay; Zviran, Asaf; Rais, Yoach; Shipony, Zohar; Mukamel, Zohar; Krupalnik, Vladislav; Zerbib, Mirie; Geula, Shay; Caspi, Inbal; Schneir, Dan; Shwartz, Tamar; Gilad, Shlomit; Amann-Zalcenstein, Daniela; Benjamin, Sima; Amit, Ido; Tanay, Amos; Massarwa, Rada; Novershtern, Noa; Hanna, Jacob H
2013-12-12
Mouse embryonic stem (ES) cells are isolated from the inner cell mass of blastocysts, and can be preserved in vitro in a naive inner-cell-mass-like configuration by providing exogenous stimulation with leukaemia inhibitory factor (LIF) and small molecule inhibition of ERK1/ERK2 and GSK3β signalling (termed 2i/LIF conditions). Hallmarks of naive pluripotency include driving Oct4 (also known as Pou5f1) transcription by its distal enhancer, retaining a pre-inactivation X chromosome state, and global reduction in DNA methylation and in H3K27me3 repressive chromatin mark deposition on developmental regulatory gene promoters. Upon withdrawal of 2i/LIF, naive mouse ES cells can drift towards a primed pluripotent state resembling that of the post-implantation epiblast. Although human ES cells share several molecular features with naive mouse ES cells, they also share a variety of epigenetic properties with primed murine epiblast stem cells (EpiSCs). These include predominant use of the proximal enhancer element to maintain OCT4 expression, pronounced tendency for X chromosome inactivation in most female human ES cells, increase in DNA methylation and prominent deposition of H3K27me3 and bivalent domain acquisition on lineage regulatory genes. The feasibility of establishing human ground state naive pluripotency in vitro with equivalent molecular and functional features to those characterized in mouse ES cells remains to be defined. Here we establish defined conditions that facilitate the derivation of genetically unmodified human naive pluripotent stem cells from already established primed human ES cells, from somatic cells through induced pluripotent stem (iPS) cell reprogramming or directly from blastocysts. The novel naive pluripotent cells validated herein retain molecular characteristics and functional properties that are highly similar to mouse naive ES cells, and distinct from conventional primed human pluripotent cells. This includes competence in the generation
Many-body Expanded Analytical Potential Energy Function for Ground State PuOH Molecule
Institute of Scientific and Technical Information of China (English)
LI Yue-Xun; GAO Tao; ZHU Zheng-He
2006-01-01
Using the density functional method B3LYP with relativistic effective core potential (RECP) for Pu atom, the low-lying excited states (4∑+, 6∑+, 8∑+) for three structures of PuOH molecule were optimized. The results show that the ground state is X6∑+of the linear Pu-O-H (C∞v), its corresponding equilibrium geometry and dissociation energy are RPu-O=0.20595 nm, RO-H=0.09581 nm and -8.68 eV, respectively. At the same time, two other metastable structures [PuOH (Cs) and H-Pu-O (C∞v)] were found. The analytical potential energy function has also been derived for whole range using the many-body expansion method. This potential energy function represents the considerable topographical features of PuOH molecule in detail, which is adequately accurate in the whole potential surface and can be used for the molecular reaction dynamics research.
Structures of Annulenes and Model Annulene Systems in the Ground and Lowest Excited States
Directory of Open Access Journals (Sweden)
Pier Remigio Salvi
2010-11-01
Full Text Available The paper introduces general considerations on structural properties of aromatic, antiaromatic and non-aromatic conjugated systems in terms of potential energy along bond length alternation and distortion coordinates, taking as examples benzene, cyclobutadiene and cyclooctatetraene. Pentalene, formally derived from cyclooctatetraene by cross linking, is also considered as a typical antiaromatic system. The main interest is concerned with [n]annulenes and model [n]annulene molecular systems, n ranging from 10 to 18. The rich variety of conformational and configurational isomers and of dynamical processes among them is described. Specific attention is devoted to bridged [10]- and [14]annulenes in the ground and lowest excited states as well as to s-indacene and biphenylene. Experimental data obtained from vibrational and electronic spectroscopies are discussed and compared with ab initio calculation results. Finally, porphyrin, tetraoxaporphyrin dication and diprotonated porphyrin are presented as annulene structures adopting planar/non-planar geometries depending on the steric hindrance in the inner macrocycle ring. Radiative and non-radiative relaxation processes from excited state levels have been observed by means of time-resolved fluorescence and femtosecond transient absorption spectroscopy. A short account is also given of porphycene, the structural isomer of porphyrin, and of porphycene properties.
Park, Sunghun; Recher, Patrik
2015-12-11
A phase from an adiabatic exchange of Majorana bound states (MBS) reveals their exotic anyonic nature. For detecting this exchange phase, we propose an experimental setup consisting of a Corbino geometry Josephson junction on the surface of a topological insulator, in which two MBS at zero energy can be created and rotated. We find that if a metallic tip is weakly coupled to a point on the junction, the time-averaged differential conductance of the tip-Majorana coupling shows peaks at the tip voltages eV=±(α-2πl)ℏ/T_{J}, where α=π/2 is the exchange phase of the two circulating MBS, T_{J} is the half rotation time of MBS, and l an integer. This result constitutes a clear experimental signature of Majorana fermion exchange.
Counting charged massless states in the (0,2) heterotic CFT/geometry connection
Beccaria, Matteo; Puhm, Andrea
2010-01-01
We use simple current techniques and their relation to orbifolds with discrete torsion for studying the (0,2) CFT/geometry duality with non-rational internal $N=2$ SCFTs. Explicit formulas for the charged spectra of heterotic $SO(10)$ GUT models are computed in terms of their extended Poincar\\'{e} polynomials and the complementary Poincar\\'{e} polynomial which can be computed in terms of the elliptic genera. While non-BPS states contribute to the charged spectrum, their contributions can be determined also for non-rational cases. For model building, with generalizations to $SU(5)$ and SM gauge groups, one can take advantage of the large class of Landau-Ginzburg orbifold examples.
Zhang, Tianyuan; Evangelista, Francesco A
2016-09-13
In this work we propose a novel approach to solve the Schrödinger equation which combines projection onto the ground state with a path-filtering truncation scheme. The resulting projector configuration interaction (PCI) approach realizes a deterministic version of the full configuration interaction quantum Monte Carlo (FCIQMC) method [Booth, G. H.; Thom, A. J. W.; Alavi, A. J. Chem. Phys. 2009, 131, 054106]. To improve upon the linearized imaginary-time propagator, we develop an optimal projector scheme based on an exponential Chebyshev expansion in the limit of an infinite imaginary time step. After writing the exact projector as a path integral in determinant space, we introduce a path filtering procedure that truncates the size of the determinantal basis and approximates the Hamiltonian. The path filtering procedure is controlled by one real threshold that determines the accuracy of the PCI energy and is not biased toward any determinant. Therefore, the PCI approach can equally well describe static and dynamic electron correlation effects. This point is illustrated in benchmark computations on N2 at both equilibrium and stretched geometries. In both cases, the PCI achieves chemical accuracy with wave functions that contain less than 0.5% determinants of full CI space. We also report computations on the ground state of C2 with up to quaduple-ζ basis sets and wave functions as large as 200 million determinants, which allow a direct comparison of the PCI, FCIQMC, and density matrix renormalization group (DMRG) methods. The size of the PCI wave function grows modestly with the number of unoccupied orbitals, and its accuracy may be tuned to match that of FCIQMC and DMRG.
E2 transitions between excited single-phonon states: Role of ground-state correlations
Energy Technology Data Exchange (ETDEWEB)
Kamerdzhiev, S. P. [National Research Centre Kurchatov Institute (Russian Federation); Voitenkov, D. A., E-mail: dvoytenkov@ippe.ru [Institute for Physics and Power Engineering (Russian Federation)
2016-11-15
The probabilities for E2 transitions between low-lying excited 3{sup −} and 5{sup −} single-phonon states in the {sup 208}Pb and {sup 132}Sn magic nuclei are estimated on the basis of the theory of finite Fermi systems. The approach used involves a new type of ground-state correlations, that which originates from integration of three (rather than two, as in the random-phase approximation) single-particle Green’s functions. These correlations are shown to make a significant contribution to the probabilities for the aforementioned transitions.
Pan, Yi; Lau, Kai-Chung; Al-Mogren, Muneerah Mogren; Mahjoub, Ahmed; Hochlaf, Majdi
2014-10-01
We treat theoretically 2-quinolinol(lactam), an analog of carbostyril and DNA bases. We characterized the ground state structure of 2-quinolinol and its isomer(lactim) using density functional theory(DFT). The reaction profile and energetics for lactam-lactim tautomerization and cis-lactim to trans-lactim isomerization predicted with explicitly correlated methods. We explored the pattern of the lowest singlet and triplet manifolds of states and electronic S1 ← S0 transitions using multiconfigurational methodologies. The theoretical results are compared with available experimental data and used to interpret the on-going photoelectron study of 2-quinolinol. Our analysis should help to understand the effect of tautomerism and aromaticity on the DNA bases.
On the State Space Geometry of the Kuramoto--Sivashinsky Flow in a Periodic Domain
Cvitanovic, Predrag; Davidchack, Ruslan L.; Siminos, Evangelos
2010-01-01
The continuous and discrete symmetries of the Kuramoto-Sivashinsky system restricted to a spatially periodic domain play a prominent role in shaping the invariant sets of its chaotic dynamics. The continuous spatial translation symmetry leads to relative equilibrium (traveling wave) and relative periodic orbit (modulated traveling wave) solutions. The discrete symmetries lead to existence of equilibrium and periodic orbit solutions, induce decomposition of state space into invariant subspaces, and enforce certain structurally stable heteroclinic connections between equilibria. We show, for the example of a particular small-cell Kuramoto-Sivashinsky system, how the geometry of its dynamical state space is organized by a rigid cage built by heteroclinic connections between equilibria, and demonstrate the preponderance of unstable relative periodic orbits and their likely role as the skeleton underpinning spatiotemporal turbulence in systems with continuous symmetries. We also offer novel visualizations of the high-dimensional Kuramoto-Sivashinsky state space flow through projections onto low-dimensional, PDE representation-independent, dynamically invariant intrinsic coordinate frames, as well as in terms of the physical, symmetry invariant energy transfer rates.
Geometry from Information Geometry
Caticha, Ariel
2015-01-01
We use the method of maximum entropy to model physical space as a curved statistical manifold. It is then natural to use information geometry to explain the geometry of space. We find that the resultant information metric does not describe the full geometry of space but only its conformal geometry -- the geometry up to local changes of scale. Remarkably, this is precisely what is needed to model "physical" space in general relativity.
Ground State of a Two-Electron Quantum Dot with a Gaussian Confining Potential
Institute of Scientific and Technical Information of China (English)
XIE Wen-Fang
2006-01-01
We investigate the ground-state properties of a two-dimensional two-electron quantum dot with a Gaussian confining potential under the influence of perpendicular homogeneous magnetic field. Calculations are carried out by using the method of numerical diagonalization of Hamiltonian matrix within the effective-mass approximation. A ground-state behaviour (singlet→triplet state transitions) as a function of the strength of a magnetic field has been found. It is found that the dot radius R of the Gaussian potential is important for the ground-state transition and the feature of ground-state for the Gaussian potential quantum dot (QD), and the parabolic potential QDs are similar when R is larger. The larger the quantum dot radius, the smaller the magnetic field for the singlet-triplet transition of the ground-state of two interacting electrons in the Gaussian quantum dot.
Ground-state and excited-state structures of tungsten-benzylidyne complexes
Energy Technology Data Exchange (ETDEWEB)
Lovaasen, B. M.; Lockard, J. V.; Cohen, B. W.; Yang, S.; Zhang, X.; Simpson, C. K.; Chen, L. X.; Hopkins, M. D. (Chemical Sciences and Engineering Division); ( XSD); (The Univ. of Chicago)
2012-01-01
The molecular structure of the tungsten-benzylidyne complex trans-W({triple_bond}CPh)(dppe){sub 2}Cl (1; dppe = 1,2-bis(diphenylphosphino)ethane) in the singlet (d{sub xy}){sup 2} ground state and luminescent triplet (d{sub xy}){sup 1}({pi}*(WCPh)){sup 1} excited state (1*) has been studied using X-ray transient absorption spectroscopy, X-ray crystallography, and density functional theory (DFT) calculations. Molecular-orbital considerations suggest that the W-C and W-P bond lengths should increase in the excited state because of the reduction of the formal W-C bond order and decrease in W {yields} P {pi}-backbonding, respectively, between 1 and 1*. This latter conclusion is supported by comparisons among the W-P bond lengths obtained from the X-ray crystal structures of 1, (d{sub xy}){sup 1}-configured 1{sup +}, and (d{sub xy}){sup 2} [W(CPh)(dppe){sub 2}(NCMe)]{sup +} (2{sup +}). X-ray transient absorption spectroscopic measurements of the excited-state structure of 1* reveal that the W-C bond length is the same (within experimental error) as that determined by X-ray crystallography for the ground state 1, while the average W-P/W-Cl distance increases by 0.04 {angstrom} in the excited state. The small excited-state elongation of the W-C bond relative to the M-E distortions found for M({triple_bond}E)L{sub n} (E = O, N) compounds with analogous (d{sub xy}){sup 1}({pi}*(ME)){sup 1} excited states is due to the {pi} conjugation within the WCPh unit, which lessens the local W-C {pi}-antibonding character of the {pi}*(WCPh) lowest unoccupied molecular orbital (LUMO). These conclusions are supported by DFT calculations on 1 and 1*. The similar core bond distances of 1, 1{sup +}, and 1* indicates that the inner-sphere reorganization energy associated with ground- and excited-state electron-transfer reactions is small.
Institute of Scientific and Technical Information of China (English)
鄢国森; 先晖; 谢代前
1997-01-01
A 285-pomt multi-reference configuration-interaction involving single and double excitations ( MRS DCI) potential energy surface for the electronic ground state of L12H is determined by using 6-311G (2df,2pd)basis set.A Simons-Parr-Finlan polynomial expansion is used to fit the discrete surface with a x2 of 4.64×106 The equn librium geometry occurs at Rc=0.172 nm and,LiHL1=94.10°.The dissociation energy for reaction I2H(2A)→L12(1∑g)+H(2S) is 243.910 kJ/mol,and that for reaction L12H(2A’)→HL1(1∑) + L1(2S) is 106.445 kl/mol The inversion barrier height is 50.388 kj/mol.The vibrational energy levels are calculated using the discrete variable representation (DVR) method.
Schmidt, Matthew; Constable, Steve; Ing, Christopher; Roy, Pierre-Nicholas
2014-06-21
We developed and studied the implementation of trial wavefunctions in the newly proposed Langevin equation Path Integral Ground State (LePIGS) method [S. Constable, M. Schmidt, C. Ing, T. Zeng, and P.-N. Roy, J. Phys. Chem. A 117, 7461 (2013)]. The LePIGS method is based on the Path Integral Ground State (PIGS) formalism combined with Path Integral Molecular Dynamics sampling using a Langevin equation based sampling of the canonical distribution. This LePIGS method originally incorporated a trivial trial wavefunction, ψT, equal to unity. The present paper assesses the effectiveness of three different trial wavefunctions on three isotopes of hydrogen for cluster sizes N = 4, 8, and 13. The trial wavefunctions of interest are the unity trial wavefunction used in the original LePIGS work, a Jastrow trial wavefunction that includes correlations due to hard-core repulsions, and a normal mode trial wavefunction that includes information on the equilibrium geometry. Based on this analysis, we opt for the Jastrow wavefunction to calculate energetic and structural properties for parahydrogen, orthodeuterium, and paratritium clusters of size N = 4 - 19, 33. Energetic and structural properties are obtained and compared to earlier work based on Monte Carlo PIGS simulations to study the accuracy of the proposed approach. The new results for paratritium clusters will serve as benchmark for future studies. This paper provides a detailed, yet general method for optimizing the necessary parameters required for the study of the ground state of a large variety of systems.
Energy Technology Data Exchange (ETDEWEB)
Schmidt, Matthew; Constable, Steve; Ing, Christopher; Roy, Pierre-Nicholas, E-mail: pnroy@uwaterloo.ca [Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada)
2014-06-21
We developed and studied the implementation of trial wavefunctions in the newly proposed Langevin equation Path Integral Ground State (LePIGS) method [S. Constable, M. Schmidt, C. Ing, T. Zeng, and P.-N. Roy, J. Phys. Chem. A 117, 7461 (2013)]. The LePIGS method is based on the Path Integral Ground State (PIGS) formalism combined with Path Integral Molecular Dynamics sampling using a Langevin equation based sampling of the canonical distribution. This LePIGS method originally incorporated a trivial trial wavefunction, ψ{sub T}, equal to unity. The present paper assesses the effectiveness of three different trial wavefunctions on three isotopes of hydrogen for cluster sizes N = 4, 8, and 13. The trial wavefunctions of interest are the unity trial wavefunction used in the original LePIGS work, a Jastrow trial wavefunction that includes correlations due to hard-core repulsions, and a normal mode trial wavefunction that includes information on the equilibrium geometry. Based on this analysis, we opt for the Jastrow wavefunction to calculate energetic and structural properties for parahydrogen, orthodeuterium, and paratritium clusters of size N = 4 − 19, 33. Energetic and structural properties are obtained and compared to earlier work based on Monte Carlo PIGS simulations to study the accuracy of the proposed approach. The new results for paratritium clusters will serve as benchmark for future studies. This paper provides a detailed, yet general method for optimizing the necessary parameters required for the study of the ground state of a large variety of systems.
Choi, Jinwoo; Chang, Eonho; Anstine, Dylan M.; Chakraborty, Himadri
2016-05-01
We study the ground state properties of C60 and C240 molecules in a spherical frame of local density approximation (LDA). Within this mean-field theory, two different approximations to the exchange-correlation (xc) functional are used: (i) The Gunnerson-Lundqvist parametrization augmented by a treatment to correct for the electron self-interaction and (ii) the van Leeuwen and Baerends (LB94) model potential that inclusively restores electron's asymptotic properties. Results show differences in the ground-state potential, level energies and electron densities between the two xc choices. We then use the ground structure to find the excited and ionized states of the systems and calculate dipole single-photoionization cross sections in a time-dependent LDA method that incorporates linear-response dynamical correlations. Comparative effects of the choices of xc on collective plasmon and single-excitation Auger resonances as well as on geometry driven cavity oscillations are found significant. The work is supported by the NSF, USA.
Revised Iterative Solution of Ground State of Double-Well Potential
Institute of Scientific and Technical Information of China (English)
ZHAO Wei-Qin
2005-01-01
The revised new iterative method for solving the ground state of Schrodinger equation is deduced. Based on Green functions defined by quadratures along a single trajectory this iterative method is applied to solve the ground state of the double-well potential. The result is compared to the one based on the original iterative method. The limitation of the asymptotic expansion is also discussed.
Ground state solutions for nonlinear fractional Schrodinger equations involving critical growth
Directory of Open Access Journals (Sweden)
Hua Jin
2017-03-01
Full Text Available This article concerns the ground state solutions of nonlinear fractional Schrodinger equations involving critical growth. We obtain the existence of ground state solutions when the potential is not a constant and not radial. We do not use the Ambrosetti-Rabinowitz condition, or the monotonicity condition on the nonlinearity.
Ground state correlations and mean field using the exp(S) method
Heisenberg, J H; Heisenberg, Jochen H.; Mihaila, Bogdan
1999-01-01
This document gives a detailed account of the terms used in the computation of the ground state mean field and the ground state correlations. While the general approach to this description is given in a separate paper (nucl-th/9802029) we give here the explicite expressions used.
The study of magnetization of the spin systm in the ground state
Institute of Scientific and Technical Information of China (English)
Jiang Wei; Wang Xi-Kun; Zhao Qiang
2006-01-01
Within the framework of the effective-field theory with self-spin correlations and the differential operator technique,the ground state magnetizations of the biaxial crystal field spin system on the honeycomb lattices have been studied.The influences of the biaxial crystal field on the magnetization in the ground state have been investigated in detail.
Improved lower bounds on the ground-state entropy of the antiferromagnetic Potts model.
Chang, Shu-Chiuan; Shrock, Robert
2015-05-01
We present generalized methods for calculating lower bounds on the ground-state entropy per site, S(0), or equivalently, the ground-state degeneracy per site, W=e(S(0)/k(B)), of the antiferromagnetic Potts model. We use these methods to derive improved lower bounds on W for several lattices.
Adsorption geometry and interface states: Relaxed and compressed phases of NTCDA/Ag(111)
Jakob, P.; Zaitsev, N. L.; Namgalies, A.; Tonner, R.; Nechaev, I. A.; Tautz, F. S.; Höfer, U.; Sánchez-Portal, D.
2016-09-01
The theoretical modeling of metal-organic interfaces represents a formidable challenge, especially considering the delicate balance of various interaction mechanisms and the large size of the involved molecular species. In the present study, the energies of interface states, which are known to display a high sensitivity to the adsorption geometry and electronic structure of the deposited molecular species, have been used to test the suitability and reliability of current theoretical approaches. Two well-ordered overlayer structures (relaxed and compressed monolayers) of 1,4,5,8-naphthalene-tetracarboxylic acid dianhydride (NTCDA) on Ag(111) have been investigated using two-photon photoemission to derive precise interface-state energies for these closely related systems. The experimental values are reproduced by our density-functional theory (DFT) calculations with two approaches to treat dispersion interactions (semi-empirical correction DFT-D3 and parametrized functional optB88) and basis set approaches (localized numerical atomic orbitals, plane waves) with remarkable accuracy. Our results underline the trustworthiness and some of the limitations of current DFT-based methods regarding the description of geometric and electronic properties of metal-organic interfaces.
Parniak, Michał; Wasilewski, Wojciech
2015-01-01
We demonstrate an interface between light coupled to transition between excited states of rubidium and long-lived ground-state atomic coherence. In our proof-of-principle experiment a non-linear process of four-wave mixing in an open-loop configuration is used to achieve light emission proportional to independently prepared ground-state atomic coherence. We demonstrate strong correlations between Raman light heralding generation of ground-state coherence and the new four-wave mixing signal. Dependance of the efficiency of the process on laser detunings is studied.
Guido, Ciro A; Knecht, Stefan; Kongsted, Jacob; Mennucci, Benedetta
2013-05-14
We analyze potentials and limits of the Time-Dependent Density Functional Theory (TD-DFT) approach for the determination of excited-state geometries of organic molecules in gas-phase and in solution. Three very popular DFT exchange-correlation functionals, two hybrids (B3LYP and PBE0) and one long-range corrected (CAM-B3LYP), are here investigated, and the results are compared to the correlated RI-CC2 wave function approach. Solvent effects are further analyzed by means of a polarizable continuum model. A total of 15 organic chromophores (including both small molecules and larger push-pull systems) are considered as prototypes of n → π* and π → π* singlet excitations. Our analysis allows to point out specific correlations between the accuracy of the various functionals and the type of excitation and/or the type of chemical bonds involved. We find that while the best ground-state geometries are obtained with PBE0 and B3LYP, CAM-B3LYP yields the most accurate description of electronic and geometrical characteristics of excited states, both in gas-phase and in solution.
Stevenson, I C; Chen, Y P; Elliott, D S
2016-01-01
We report a newly observed photoassociation resonance in $^7$Li-$^{85}$Rb, a mixed $2(1) - 4(1)$ excited state, that spontaneously decays to the rovibronic ground state. This resonance between ultracold Li and Rb is the strongest ground state molecule-forming photoassociation line observed in LiRb, and forms deeply bound $X \\: ^1\\Sigma^+$ molecules in large numbers. The production rate of the $v=0 \\ J=0$ rovibrational ground state is $\\sim 1.5 \\times 10^{4}$ molecules/s.
Bankfull hydraulic geometry relationships are used to estimate channel dimensions for stream flow simulation models, which require channel geometry data as input parameters. Often, one nationwide curve is used across the entire U.S. (e.g. in SWAT), even though studies have shown that the use of reg...
The significant role of covalency in determining the ground state of cobalt phthalocyanines molecule
Directory of Open Access Journals (Sweden)
Jing Zhou
2016-03-01
Full Text Available To shed some light on the metal 3d ground state configuration of cobalt phthalocyanines system, so far in debate, we present an investigation by X-ray absorption spectroscopy (XAS at Co L2,3 edge and theoretical calculation. The density functional theory calculations reveal highly anisotropic covalent bond between central cobalt ion and nitrogen ligands, with the dominant σ donor accompanied by weak π-back acceptor interaction. Our combined experimental and theoretical study on the Co-L2,3 XAS spectra demonstrate a robust ground state of 2A1g symmetry that is built from 73% 3d7 character and 27% 3 d 8 L ¯ ( L ¯ denotes a ligand hole components, as the first excited-state with 2Eg symmetry lies about 158 meV higher in energy. The effect of anisotropic and isotropic covalency on the ground state was also calculated and the results indicate that the ground state with 2A1g symmetry is robust in a large range of anisotropic covalent strength while a transition of ground state from 2A1g to 2Eg configuration when isotropic covalent strength increases to a certain extent. Here, we address a significant anisotropic covalent effect of short Co(II-N bond on the ground state and suggest that it should be taken into account in determining the ground state of analogous cobalt complexes.
Koroleva, L. A.; Krasnoshchekov, S. V.; Matveev, V. K.; Pentin, Yu. A.
2016-08-01
The structural parameters of s- trans- and s- cis-isomers of a methacrolein molecule in the ground ( S 0) electronic state are determined by means of MP2 method with the cc-pVTZ basis set. Kinematic factor F(φ) is expanded in a Fourier series. The potential function of internal rotation (PFIR) of methacrolein in this state is built using experimental frequencies of transitions of the torsional vibration of both isomers, obtained from an analysis of the vibrational structure of the high-resolution UV spectrum with allowance for the geometry and difference between the energy (Δ H) of the isomers. It is shown that the V n parameters of the potential function of internal rotation of the molecule, built using the frequencies of the transition of the torsional vibrations of s- trans- and s- cis-isomers of the methacrolein molecule, determined from vibrational structure of the high-resolution UV spectrum and the FTIR spectrum, are close.
Kumari, Rekha; Varghese, Anitha; George, Louis
2017-01-01
Absorption and fluorescence studies on novel Schiff bases (E)-4-(4-(4-nitro benzylideneamino)benzyl)oxazolidin-2-one (NBOA) and (E)-4-(4-(4-chlorobenzylidene amino)benzyl)oxazolidin-2-one (CBOA) were recorded in a series of twelve solvents upon increasing polarity at room temperature. Large Stokes shift indicates bathochromic fluorescence band for both the molecules. The photoluminescence properties of Schiff bases containing electron withdrawing and donating substituents were analyzed. Intramolecular charge transfer behavior can be studied based on the influence of different substituents in Schiff bases. Changes in position and intensity of absorption and fluorescence spectra are responsible for the stabilization of singlet excited-states of Schiff base molecules with different substituents, in polar solvents. This is attributed to the Intramolecular charge transfer (ICT) mechanism. In case of electron donating (-Cl) substituent, ICT contributes largely to positive solvatochromism when compared to electron withdrawing (-NO2) substituent. Ground-state and singlet excited-state dipole moments of NBOA and CBOA were calculated experimentally using solvent polarity function approaches given by Lippert-Mataga, Bakhshiev, Kawskii-Chamma-Viallet and Reichardt. Due to considerable π- electron density redistribution, singlet excited-state dipole moment was found to be greater than ground-state dipole moment. Ground-state dipole moment value which was determined by quantum chemical method was used to estimate excited-state dipole moment using solvatochromic correlations. Kamlet-Abboud-Taft and Catalan multiple linear regression approaches were used to study non-specific solute-solvent interaction and hydrogen bonding interactions in detail. Optimized geometry and HOMO-LUMO energies of NBOA and CBOA have been determined by DFT and TD-DFT/PCM (B3LYP/6-311G (d, p)). Mulliken charges and molecular electrostatic potential have also been evaluated from DFT calculations.
Piao, Daqing; Barbour, Randall L; Graber, Harry L; Lee, Daniel C
2015-10-01
This work analytically examines some dependences of the differential pathlength factor (DPF) for steady-state photon diffusion in a homogeneous medium on the shape, dimension, and absorption and reduced scattering coefficients of the medium. The medium geometries considered include a semi-infinite geometry, an infinite-length cylinder evaluated along the azimuthal direction, and a sphere. Steady-state photon fluence rate in the cylinder and sphere geometries is represented by a form involving the physical source, its image with respect to the associated extrapolated half-plane, and a radius-dependent term, leading to simplified formula for estimating the DPFs. With the source-detector distance and medium optical properties held fixed across all three geometries, and equal radii for the cylinder and sphere, the DPF is the greatest in the semi-infinite and the smallest in the sphere geometry. When compared to the results from finite-element method, the DPFs analytically estimated for 10 to 25 mm source–detector separations on a sphere of 50 mm radius with μa=0.01 mm(−1) and μ′s=1.0 mm(−1) are on average less than 5% different. The approximation for sphere, generally valid for a diameter≥20 times of the effective attenuation pathlength, may be useful for rapid estimation of DPFs in near-infrared spectroscopy of an infant head and for short source–detector separation.
Piao, Daqing; Barbour, Randall L.; Graber, Harry L.; Lee, Daniel C.
2015-01-01
Abstract. This work analytically examines some dependences of the differential pathlength factor (DPF) for steady-state photon diffusion in a homogeneous medium on the shape, dimension, and absorption and reduced scattering coefficients of the medium. The medium geometries considered include a semi-infinite geometry, an infinite-length cylinder evaluated along the azimuthal direction, and a sphere. Steady-state photon fluence rate in the cylinder and sphere geometries is represented by a form involving the physical source, its image with respect to the associated extrapolated half-plane, and a radius-dependent term, leading to simplified formula for estimating the DPFs. With the source-detector distance and medium optical properties held fixed across all three geometries, and equal radii for the cylinder and sphere, the DPF is the greatest in the semi-infinite and the smallest in the sphere geometry. When compared to the results from finite-element method, the DPFs analytically estimated for 10 to 25 mm source–detector separations on a sphere of 50 mm radius with μa=0.01 mm−1 and μs′=1.0 mm−1 are on average less than 5% different. The approximation for sphere, generally valid for a diameter ≥20 times of the effective attenuation pathlength, may be useful for rapid estimation of DPFs in near-infrared spectroscopy of an infant head and for short source–detector separation. PMID:26465613
Nonaxisymmetric MHD Instabilities of Chandrasekhar States in Taylor-Couette Geometry
Gellert, M.; Rüdiger, G.; Schultz, M.; Guseva, A.; Hollerbach, R.
2016-06-01
We consider axially periodic Taylor-Couette geometry with insulating boundary conditions. The imposed basic states are so-called Chandrasekhar states, where the azimuthal flow U ϕ and magnetic field B ϕ have the same radial profiles. Mainly three particular profiles are considered: the Rayleigh limit, quasi-Keplerian, and solid-body rotation. In each case we begin by computing linear instability curves and their dependence on the magnetic Prandtl number {{Pm}}. For the azimuthal wavenumber m = 1 modes, the instability curves always scale with the Reynolds number and the Hartmann number. For sufficiently small {{Pm}} these modes therefore only become unstable for magnetic Mach numbers less than unity, and are thus not relevant for most astrophysical applications. However, modes with m\\gt 1 can behave very differently. For sufficiently flat profiles, they scale with the magnetic Reynolds number and the Lundquist number, thereby allowing instability also for the large magnetic Mach numbers of astrophysical objects. We further compute fully nonlinear, three-dimensional equilibration of these instabilities, and investigate how the energy is distributed among the azimuthal (m) and axial (k) wavenumbers. In comparison spectra become steeper for large m, reflecting the smoothing action of shear. On the other hand kinetic and magnetic energy spectra exhibit similar behavior: if several azimuthal modes are already linearly unstable they are relatively flat, but for the rigidly rotating case where m = 1 is the only unstable mode they are so steep that neither Kolmogorov nor Iroshnikov-Kraichnan spectra fit the results. The total magnetic energy exceeds the kinetic energy only for large magnetic Reynolds numbers {{Rm}}\\gt 100.
Kresin, Vladimir
2008-01-01
Metallic nanoclusters displaying electronic shell structure exhibit the special feature of a correlation between their geometry and the number of delocalized electrons . Their shape evolution can be described as a quantum oscillation between quasi-resonant states (prolate and oblate configurations) whose amplitudes depend upon the degree of shell filling. The picture explains the evolution of absorption spectra and predicts a peculiar isotope effect .
Ground-state characterizations of systems predicted to exhibit L11 or L13 crystal structures
Nelson, Lance J.; Hart, Gus L. W.; Curtarolo, Stefano
2012-02-01
Despite their geometric simplicity, the crystal structures L11 (CuPt) and L13 (CdPt3) do not appear as ground states experimentally, except in Cu-Pt. We investigate the possibility that these phases are ground states in other binary intermetallic systems, but overlooked experimentally. Via the synergy between high-throughput and cluster-expansion computational methods, we conduct a thorough search for systems that may exhibit these phases and calculate order-disorder transition temperatures when they are predicted. High-throughput calculations predict L11 ground states in the systems Ag-Pd, Ag-Pt, Cu-Pt, Pd-Pt, Li-Pd, Li-Pt, and L13 ground states in the systems Cd-Pt, Cu-Pt, Pd-Pt, Li-Pd, Li-Pt. Cluster expansions confirm the appearance of these ground states in some cases. In the other cases, cluster expansion predicts unsuspected derivative superstructures as ground states. The order-disorder transition temperatures for all L11/L13 ground states were found to be sufficiently high that their physical manifestation may be possible.
Exact spin-cluster ground states in a mixed diamond chain
Takano, Ken'Ichi; Suzuki, Hidenori; Hida, Kazuo
2009-09-01
The mixed diamond chain is a frustrated Heisenberg chain composed of successive diamond-shaped units with two kinds of spins of magnitudes S and S/2 ( S : integer). Ratio λ of two exchange parameters controls the strength of frustration. With varying λ , the Haldane state and several spin-cluster states appear as the ground state. A spin-cluster state is a tensor product of exact local eigenstates of cluster spins. We prove that a spin-cluster state is the ground state in a finite interval of λ . For S=1 , we numerically determine the total phase diagram consisting of five phases.
Energy Technology Data Exchange (ETDEWEB)
Santhosh, K.P., E-mail: drkpsanthosh@gmail.co [School of Pure and Applied Physics, Kannur University, Payyanur Campus, Payyanur 670 327 (India); Sahadevan, Sabina; Joseph, Jayesh George [School of Pure and Applied Physics, Kannur University, Payyanur Campus, Payyanur 670 327 (India)
2011-01-15
Alpha half lives, branching ratios and hindrance factors of even-even nuclei in the range 78{<=}Z{<=}102 from ground state to ground state and ground state to excited states of daughter nuclei are computed using the Coulomb and proximity potential model for deformed nuclei (CPPMDN). The computed half life values and branching ratios are compared with experimental data and they are in good agreement. The standard deviation of half life and branching ratio are 0.79 and 0.94 respectively. It is found that the standard deviation of branching ratio for the ground state to ground state transition is only 0.25 and it increases as we move to the higher excited states which are due to the effect of nuclear structure. It is evident from the study that our ground state decay model is apt for describing not only the ground state to ground state decay but also decay to excited state.
A remark on ground state of boundary Izergin-Korepin model
Kojima, Takeo
2011-01-01
We study the ground state of the boundary Izergin-Korepin model. The boundary Izergin-Korepin model is defined by so-called $R$-matrix and $K$-matrix for $U_q(A_2^{(2)})$ which satisfy Yang-Baxter equation and boundary Yang-Baxter equation respectively. The ground state associated with identity $K$-matrix $K(z)=id$ was constructed in earlier study [Yang and Zhang, Nucl.Phys.B596,495-(2001)]. We construct the free field realization of the ground state associated with nontrivial diagonal $K$-matrix.
Characterization of ground state entanglement by single-qubit operations and excitation energies
Giampaolo, S M; Illuminati, F; Verrucchi, P; Giampaolo, Salvatore M.; Illuminati, Fabrizio; Siena, Silvio De; Verrucchi, Paola
2006-01-01
We consider single-qubit unitary operations and study the associated excitation energies above the ground state of interacting quantum spins. We prove that there exists a unique operation such that the vanishing of the corresponding excitation energy determines a necessary and sufficient condition for the separability of the ground state. We show that the energy difference associated to factorization exhibits a monotonic behavior with the one-tangle and the entropy of entanglement, including non analiticity at quantum critical points. The single-qubit excitation energy thus provides an independent, directly observable characterization of ground state entanglement, and a simple relation connecting two universal physical resources, energy and nonlocal quantum correlations.
Efficient sympathetic motional ground-state cooling of a molecular ion
Wan, Yong; Wolf, Fabian; Schmidt, Piet O
2015-01-01
Cold molecular ions are promising candidates in various fields ranging from precision spectroscopy and test of fundamental physics to ultra-cold chemistry. Control of internal and external degrees of freedom is a prerequisite for many of these applications. Motional ground state cooling represents the starting point for quantum logic-assisted internal state preparation, detection, and spectroscopy protocols. Robust and fast cooling is crucial to maximize the fraction of time available for the actual experiment. We optimize the cooling rate of ground state cooling schemes for single $^{25}\\mathrm{Mg}^{+}$ ions and sympathetic ground state cooling of $^{24}\\mathrm{MgH}^{+}$. In particular, we show that robust cooling is achieved by combining pulsed Raman sideband cooling with continuous quench cooling. Furthermore, we experimentally demonstrate an efficient strategy for ground state cooling outside the Lamb-Dicke regime.
Ground-state energies of the nonlinear sigma model and the Heisenberg spin chains
Zhang, Shoucheng; Schulz, H. J.; Ziman, Timothy
1989-01-01
A theorem on the O(3) nonlinear sigma model with the topological theta term is proved, which states that the ground-state energy at theta = pi is always higher than the ground-state energy at theta = 0, for the same value of the coupling constant g. Provided that the nonlinear sigma model gives the correct description for the Heisenberg spin chains in the large-s limit, this theorem makes a definite prediction relating the ground-state energies of the half-integer and the integer spin chains. The ground-state energies obtained from the exact Bethe ansatz solution for the spin-1/2 chain and the numerical diagonalization on the spin-1, spin-3/2, and spin-2 chains support this prediction.
User's manual for EVITS: a steady state fluids code for complex two-dimensional geometries
Energy Technology Data Exchange (ETDEWEB)
Domanus, H.M.
1976-07-01
A 2-D computer code, EVITS, has been developed for estimating steady state, incompressible, isothermal flow fields in complex geometries. A vorticity-stream function formulation is used along with a model to resolve viscous effects at solid boundaries. Sufficient geometry and boundary type options are included within the code so that a large number of flow situations can be specified without modifying the program. All instructions to the code are via an input dataset. Detailed instructions for preparing the user oriented input, along with examples, are included in this users' manual.
A Rigorous Investigation on the Ground State of the Penson-Kolb Model
Institute of Scientific and Technical Information of China (English)
YANG Kai-Hua; TIAN Guang-Shan; HAN Ru-Qi
2003-01-01
By using either numerical calculations or analytical methods, such as the bosonization technique, the ground state of the Penson-Kolb model has been previously studied by several groups. Some physicists argued that, as far as the existence of superconductivity in this model is concerned, it is canonically equivalent to the negative-U Hubbard model.However, others did not agree. In the present paper, we shall investigate this model by an independent and rigorous approach. We show that the ground state of the Penson-Kolb model is nondegenerate and has a nonvanishing overlap with the ground state of the negative-U Hubbard model. Furthermore, we also show that the ground states of both the models have the same good quantum numbers and may have superconducting long-range order at the same momentum q ＝ 0. Our results support the equivalence between these models.
Bott periodicity for Z2 symmetric ground states of gapped free-fermion systems
Kennedy, Ricardo
2014-01-01
Building on the symmetry classification of disordered fermions, we give a proof of the proposal by Kitaev, and others, for a "Bott clock" topological classification of free-fermion ground states of gapped systems with symmetries. Our approach differs from previous ones in that (i) we work in the standard framework of Hermitian quantum mechanics over the complex numbers, (ii) we directly formulate a mathematical model for ground states rather than spectrally flattened Hamiltonians, and (iii) we use homotopy-theoretic tools rather than K-theory. Key to our proof is a natural transformation that squares to the standard Bott map and relates the ground state of a d-dimensional system in symmetry class s to the ground state of a (d+1)-dimensional system in symmetry class s+1. This relation gives a new vantage point on topological insulators and superconductors.
Trajectory approach to the Schrödinger–Langevin equation with linear dissipation for ground states
Energy Technology Data Exchange (ETDEWEB)
Chou, Chia-Chun, E-mail: ccchou@mx.nthu.edu.tw
2015-11-15
The Schrödinger–Langevin equation with linear dissipation is integrated by propagating an ensemble of Bohmian trajectories for the ground state of quantum systems. Substituting the wave function expressed in terms of the complex action into the Schrödinger–Langevin equation yields the complex quantum Hamilton–Jacobi equation with linear dissipation. We transform this equation into the arbitrary Lagrangian–Eulerian version with the grid velocity matching the flow velocity of the probability fluid. The resulting equation is simultaneously integrated with the trajectory guidance equation. Then, the computational method is applied to the harmonic oscillator, the double well potential, and the ground vibrational state of methyl iodide. The excellent agreement between the computational and the exact results for the ground state energies and wave functions shows that this study provides a synthetic trajectory approach to the ground state of quantum systems.
Exact ground-state phase diagrams for the spin-3/2 Blume Emery Griffiths model
Canko, Osman; Deviren, Bayram; Keskin, Mustafa
2008-05-01
We have calculated the exact ground-state phase diagrams of the spin-3/2 Ising model using the method that was proposed and applied to the spin-1 Ising model by Dublenych (2005 Phys. Rev. B 71 012411). The calculated, exact ground-state phase diagrams on the diatomic and triangular lattices with the nearest-neighbor (NN) interaction have been presented in this paper. We have obtained seven and 15 topologically different ground-state phase diagrams for J>0 and Jnon-uniform phases. We have also constructed the exact ground-state phase diagrams of the model on the triangular lattice and found 20 and 59 fundamental phase diagrams for J>0 and J<0, respectively, the conditions for the existence of uniform and intermediate phases have also been found.
Vacuum polarization screening corrections to the ground state energy of two-electron ions
Artemiev, A N; Yerokhin, V A
1997-01-01
Vacuum polarization screening corrections to the ground state energy of two-electron ions are calculated in the range $Z=20-100$. The calculations are carried out for a finite nucleus charge distribution.
Precision study of ground state capture in the 14N(p,gamma)15O reaction
Marta, M; Gyurky, Gy; Bemmerer, D; Broggini, C; Caciolli, A; Corvisiero, P; Costantini, H; Elekes, Z; Fülöp, Z; Gervino, G; Guglielmetti, A; Gustavino, C; Imbriani, G; Junker, M; Kunz, R; Lemut, A; Limata, B; Mazzocchi, C; Menegazzo, R; Prati, P; Roca, V; Rolfs, C; Romano, M; Alvarez, C Rossi; Somorjai, E; Straniero, O; Strieder, F; Terrasi, F; Trautvetter, H P; Vomiero, A
2008-01-01
The rate of the hydrogen-burning carbon-nitrogen-oxygen (CNO) cycle is controlled by the slowest process, 14N(p,gamma)15O, which proceeds by capture to the ground and several excited states in 15O. Previous extrapolations for the ground state contribution disagreed by a factor 2, corresponding to 15% uncertainty in the total astrophysical S-factor. At the Laboratory for Underground Nuclear Astrophysics (LUNA) 400 kV accelerator placed deep underground in the Gran Sasso facility in Italy, a new experiment on ground state capture has been carried out at 317.8, 334.4, and 353.3 keV center-of-mass energy. Systematic corrections have been reduced considerably with respect to previous studies by using a Clover detector and by adopting a relative analysis. The previous discrepancy has been resolved, and ground state capture no longer dominates the uncertainty of the total S-factor.
A study of the ground states of CaC2H+2,CaC2D+2 and CaC2H+4
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
The geometries, vibrational frequencies and bind energies are reported for the ground states of CaC2H+2, CaC2D+2 and CaC2H+4. CaC2H+2 and CaC2H+4 equilibrium geometries have C2v symmetry with the metal ion lying in the perpendicular bisector of the C-C bond. The ground state in both CaC2H+2 and CaC2H+4 molecules ia a 2A1 state and the binding in the ground state is mainly electrostatic. For both CaC2H+2 and CaC2H+4 the ligand is only slightly distorted from its free ligand structure, the C-C distance has hardly increased and there is only a very small bending of the H atom away from the Ca atom. This is consistent with the electrostatic nature of the bonding. Two different approaches-Hartree-Fock(HF) and density functional theory methods(DFT)-are used and basis sets here used is 6-311+G(3df,2p). The DFT results are in good agreement with experiments, namely, DFT methods provide the benefits that some more expensive ab initio methods can do, but at essentially HF cost. So it is important to include electron correlation for accurate results in this study.
Ground-state entanglement in a three-spin transverse Ising model with energy current
Institute of Scientific and Technical Information of China (English)
Zhang Yong; Liu Dan; Long Gui-Lu
2007-01-01
The ground-state entanglement associated with a three-spin transverse Ising model is studied. By introducing an energy current into the system, a quantum phase transition to energy-current phase may be presented with the variation of external magnetic field; and the ground-state entanglement varies suddenly at the critical point of quantum phase transition. In our model, the introduction of energy current makes the entanglement between any two qubits become maximally robust.
Expectation values of single-particle operators in the random phase approximation ground state.
Kosov, D S
2017-02-07
We developed a method for computing matrix elements of single-particle operators in the correlated random phase approximation ground state. Working with the explicit random phase approximation ground state wavefunction, we derived a practically useful and simple expression for a molecular property in terms of random phase approximation amplitudes. The theory is illustrated by the calculation of molecular dipole moments for a set of representative molecules.
Ground-State Density Profiles of One-Dimensional Bose Gases with Anisotropic Transversal Confinement
Institute of Scientific and Technical Information of China (English)
HAO Ya-Jiang
2011-01-01
We investigate the ground-state density distributions of interacting one-dimensional Bose gases with anisotropic transversal confinement.Combining the exact ground state energy density of homogeneous bose gases with local density approximation,we determine the density distribution in each interacting regime for different anisotropic parameters.It is shown that the transversal anisotropic parameter changes the density distribution obviously,and the observed density profiles on each orientation exhibit a difference of a factor.
Hyperfine splitting of the dressed hydrogen atom ground state in non-relativistic QED
Amour, L
2010-01-01
We consider a spin-1/2 electron and a spin-1/2 nucleus interacting with the quantized electromagnetic field in the standard model of non-relativistic QED. For a fixed total momentum sufficiently small, we study the multiplicity of the ground state of the reduced Hamiltonian. We prove that the coupling between the spins of the charged particles and the electromagnetic field splits the degeneracy of the ground state.
Hyperfine splitting in non-relativistic QED: uniqueness of the dressed hydrogen atom ground state
Amour, Laurent
2011-01-01
We consider a free hydrogen atom composed of a spin-1/2 nucleus and a spin-1/2 electron in the standard model of non-relativistic QED. We study the Pauli-Fierz Hamiltonian associated with this system at a fixed total momentum. For small enough values of the fine-structure constant, we prove that the ground state is unique. This result reflects the hyperfine structure of the hydrogen atom ground state.
Universal Wave Function Overlap and Universal Topological Data from Generic Gapped Ground States
2014-01-01
We propose a way -- universal wave function overlap -- to extract universal topological data from generic ground states of gapped systems in any dimensions. Those extracted topological data should fully characterize the topological orders with gapped or gapless boundary. For non-chiral topological orders in 2+1D, this universal topological data consist of two matrices, $S$ and $T$, which generate a projective representation of $SL(2,\\mathbb Z)$ on the degenerate ground state Hilbert space on ...
Institute of Scientific and Technical Information of China (English)
WU Feng; HE Pei; CHEN Zu-Yao; JIANG Wan-Quan
2000-01-01
The effect of the shape of suspension particle in electrorheological (ER) fluid on the ground state structure of ER solid is discussed. The results of computation show that the ground state structure will change with the shape of suspension particle. This phenomenon is a kind of phase transitions that takes the shape factors of suspension particle as tuning parameters. The variation-value of interaction energy of the lattice structure of ER solid with the shape factors of suspension particle is sometimes noticeable.
Expectation values of single-particle operators in the random phase approximation ground state
Kosov, D. S.
2017-02-01
We developed a method for computing matrix elements of single-particle operators in the correlated random phase approximation ground state. Working with the explicit random phase approximation ground state wavefunction, we derived a practically useful and simple expression for a molecular property in terms of random phase approximation amplitudes. The theory is illustrated by the calculation of molecular dipole moments for a set of representative molecules.
Chen, Suanrong
Fractal geometry has gained great attention from mathematicians and scientists in the past three decades (Fraboni & Moller, 2008). As a new geometry language and subject, fractal geometry has significant value in teaching and learning secondary mathematics. The present study focused on investigating the current state of mathematics teachers' awareness, interest, and knowledge of fractal geometry in the United States (U.S.) and China, as well as the factors that influence them. The instrument of the study included a survey and a test designed by the researcher and validated by five experts. The results of the study indicated that secondary math teachers in the U.S. and China had very low levels of awareness of fractals and lack the knowledge and skills of solving fractal problems, but they had a higher level of interest in fractals related to classroom teaching and professional development as compared with their levels of awareness. Furthermore, the results of this study indicated that the factor 'experience of learning fractals' had the most positive effect on the average score of awareness. The factor nationality (U.S.) had the most positive effect on the average score of interest. The factor nationality (U.S.) had the most negative effect on the average score of knowledge.
Patterns of the ground states in the presence of random interactions: nucleon systems
Zhao, Y M; Shimizu, N; Ogawa, K; Yoshinaga, N; Scholten, O
2004-01-01
We present our results on properties of ground states for nucleonic systems in the presence of random two-body interactions. In particular we present probability distributions for parity, seniority, spectroscopic (i.e., in the laboratory framework) quadrupole moments and $\\alpha$ clustering in the ground states. We find that the probability distribution for the parity of the ground states obtained by a two-body random ensemble simulates that of realistic nuclei: positive parity is dominant in the ground states of even-even nuclei while for odd-odd nuclei and odd-mass nuclei we obtain with almost equal probability ground states with positive and negative parity. In addition we find that for the ground states, assuming pure random interactions, low seniority is not favored, no dominance of positive values of spectroscopic quadrupole deformation, and no sign of $\\alpha$-cluster correlations, all in sharp contrast to realistic nuclei. Considering a mixture of a random and a realistic interaction, we observe a sec...
Ground-State Phases of Anisotropic Mixed Diamond Chains with Spins 1 and 1/2
Hida, Kazuo
2014-11-01
The ground-state phases of anisotropic mixed diamond chains with spins 1 and 1/2 are investigated. Both single-site and exchange anisotropies are considered. We find the phases consisting of an array of uncorrelated spin-1 clusters separated by singlet dimers. Except in the simplest case where the cluster consists of a single S = 1 spin, this type of ground state breaks the translational symmetry spontaneously. Although the mechanism leading to this type of ground state is the same as that in the isotropic case, it is nonmagnetic or paramagnetic depending on the competition between two types of anisotropy. We also find the Néel, period-doubled Néel, Haldane, and large-D phases, where the ground state is a single spin cluster of infinite size equivalent to the spin-1 Heisenberg chain with alternating anisotropies. The ground-state phase diagrams are determined for typical sets of parameters by numerical analysis. In various limiting cases, the ground-state phase diagrams are determined analytically. The low-temperature behaviors of magnetic susceptibility and entropy are investigated to distinguish each phase by observable quantities. The relationship of the present model with the anisotropic rung-alternating ladder with spin-1/2 is also discussed.
Choi, J
2016-01-01
We report our detailed analysis of a table-top system for the measurement of the weak-force-induced electric dipole moment of a ground state hyperfine transition carried out in an atomic beam geometry. We describe an experimental configuration of conductors for application of orthogonal r.f. and static electric fields, with cavity enhancement of the r.f. field amplitude, that allows confinement of the r.f. field to a region in which the static fields are uniform and well-characterized. We carry out detailed numerical simulations of the field modes, and analyze the expected magnitude of statistical and systematic limits to the measurement of this transition amplitude in atomic cesium. The combination of an atomic beam with this configuration leads to strong suppression of magnetic dipole contributions to the atomic signal. The application of this technique to the measurement of extremely weak transition amplitudes in other atomic systems, especially alkali metals, seems very feasible.
Alpha decay of {sup 184-224}Bi isotopes from the ground state and isomeric state
Energy Technology Data Exchange (ETDEWEB)
Santhosh, K.P.; Priyanka, B. [Kannur University, School of Pure and Applied Physics, Kerala (India)
2013-12-15
The {alpha} -decay half-lives for the favored and unfavored transitions of the isotopes of Bi (Z = 83) nuclei in the region 184 {<=}A {<=} 224, from both the ground state (g.s.) and the isomeric state (i.s.) have been studied systematically within the Coulomb and proximity potential model (CPPM). The half-lives have been evaluated using the experimental Q-values. The computed half-lives are compared with the experimental data and they are in good agreement. We have modified the assault frequency and redetermined the half-lives and they show a better agreement with the experimental value. The standard deviation of the logarithm of the half-life with the former assault frequency is found to be 1.234 and with the modified assault frequency, it is found to be 0.935. This reveals that the CPPM, with the modified deformation-dependent assault frequency is more apt for the alpha-decay studies. Using our model we could also demonstrate the influence of the N = 126, neutron shell closure in both parent and daughter nuclei on the alpha-decay half-lives. (orig.)
Suo, Bingbing; Han, Huixian
2014-01-01
We present the fully relativistic multi-reference configuration interaction calculations of the ground and low-lying excited electronic states of IrO for individual spin-orbit component. The lowest states for four spin-orbit components 1/2, 3/2, 5/2, and 7/2 are calculated intensively to clarify the ground state of IrO. Our calculation suggests that the ground state is of 1/2 spin-orbit component, which is highly mixed with $^4\\Sigma^-$ and $^2\\Pi$ states in $\\Lambda-S$ notation. The two low-lying states of the 5/2 and 7/2 spin-orbit components are nearly degenerate with the ground state and locate only 234 and 260 cm$^{-1}$ above, respectively. The equilibrium bond length 1.712 \\AA \\ and harmonic vibrational frequency 903 cm$^{-1}$ of the 5/2 spin-orbit component are close to the experimental measurement of 1.724 \\AA \\ and 909 cm$^{-1}$, which suggests the 5/2 state should be the low-lying state contributed to spectra in experimental study. Moreover, the electronic states that give rise to the observed trans...
Ordered ground states of metallic hydrogen and deuterium
Ashcroft, N. W.
1981-01-01
The physical attributes of some of the more physically distinct ordered states of metallic hydrogen and metallic deuterium at T = 0 and nearby are discussed. The likelihood of superconductivity in both is considered with respect to the usual coupling via the density fluctuations of the ions.
Delin, Geoffrey N.; Risser, Dennis W.
2007-01-01
Increased demands on water resources by a growing population and recent droughts have raised awareness about the adequacy of ground-water resources in humid areas of the United States. The spatial and temporal variability of ground-water recharge are key factors that need to be quantified to determine the sustainability of ground-water resources. Ground-water recharge is defined herein as the entry into the saturated zone of water made available at the water-table surface, together with the associated flow away from the water table within the saturated zone (Freeze and Cherry, 1979). In response to the need for better estimates of ground-water recharge, the Ground-Water Resources Program (GWRP) of the U.S. Geological Survey (USGS) began an initiative in 2003 to estimate ground-water recharge rates in the relatively humid areas of the United States.
Bandyopadhyay, Subhajit; Roy, Saswata
2014-01-01
This paper describes an inexpensive experiment to determine the carbonyl stretching frequency of an organic keto compound in its ground state and first electronic excited state. The experiment is simple to execute, clarifies some of the fundamental concepts of spectroscopy, and is appropriate for a basic spectroscopy laboratory course. The…
Bandyopadhyay, Subhajit; Roy, Saswata
2014-01-01
This paper describes an inexpensive experiment to determine the carbonyl stretching frequency of an organic keto compound in its ground state and first electronic excited state. The experiment is simple to execute, clarifies some of the fundamental concepts of spectroscopy, and is appropriate for a basic spectroscopy laboratory course. The…
Degenerate ground states and multiple bifurcations in a two-dimensional q-state quantum Potts model.
Dai, Yan-Wei; Cho, Sam Young; Batchelor, Murray T; Zhou, Huan-Qiang
2014-06-01
We numerically investigate the two-dimensional q-state quantum Potts model on the infinite square lattice by using the infinite projected entangled-pair state (iPEPS) algorithm. We show that the quantum fidelity, defined as an overlap measurement between an arbitrary reference state and the iPEPS ground state of the system, can detect q-fold degenerate ground states for the Z_{q} broken-symmetry phase. Accordingly, a multiple bifurcation of the quantum ground-state fidelity is shown to occur as the transverse magnetic field varies from the symmetry phase to the broken-symmetry phase, which means that a multiple-bifurcation point corresponds to a critical point. A (dis)continuous behavior of quantum fidelity at phase transition points characterizes a (dis)continuous phase transition. Similar to the characteristic behavior of the quantum fidelity, the magnetizations, as order parameters, obtained from the degenerate ground states exhibit multiple bifurcation at critical points. Each order parameter is also explicitly demonstrated to transform under the Z_{q} subgroup of the symmetry group of the Hamiltonian. We find that the q-state quantum Potts model on the square lattice undergoes a discontinuous (first-order) phase transition for q=3 and q=4 and a continuous phase transition for q=2 (the two-dimensional quantum transverse Ising model).
Nedeljković, N. N.; Majkić, M. D.; Božanić, D. K.; Dojčilović, R. J.
2016-06-01
We consider the population dynamics of the intermediate Rydberg states of highly charged ions (core charge Z\\gg 1, principal quantum number {n}{{A}}\\gg 1) interacting with solid surfaces at arbitrary collision geometry. The recently developed resonant two-state vector model for the grazing incidence (2012 J. Phys. B: At. Mol. Opt. Phys. 45 215202) is extended to the quasi-resonant case and arbitrary angle of incidence. According to the model, the population probabilities depend both on the projectile parallel and perpendicular velocity components, in a complementary way. A cascade neutralization process for {{{Xe}}}Z+ ions, for Z=15{--}45, interacting with a conductive-surface is considered by taking into account the population dynamics. For an arbitrary collision geometry and given range of ionic velocities, a micro-staircase model for the simultaneous calculation of the kinetic energy gain and the charge state of the ion in front of the surface is proposed. The relevance of the obtained results for the explanation of the formation of nanostructures on solid surfaces by slow highly charged ions for normal incidence geometry is briefly discussed.
Tillman, Fred D; Leake, Stanley A.; Flynn, Marilyn E.; Cordova, Jeffrey T.; Schonauer, Kurt T.; Dickinson, Jesse E.
2008-01-01
Monitoring the status and trends in the availability of the Nation's ground-water supplies is important to scientists, planners, water managers, and the general public. This is especially true in the semiarid to arid southwestern United States where rapid population growth and limited surface-water resources have led to increased use of ground-water supplies and water-level declines of several hundred feet in many aquifers. Individual well observations may only represent aquifer conditions in a limited area, and wells may be screened over single or multiple aquifers, further complicating single-well interpretations. Additionally, changes in ground-water conditions may involve time scales ranging from days to many decades, depending on the timing of recharge, soil and aquifer properties, and depth to the water table. The lack of an easily identifiable ground-water property indicative of current conditions, combined with differing time scales of water-level changes, makes the presentation of ground-water conditions a difficult task, particularly on a regional basis. One approach is to spatially present several indicators of ground-water conditions that address different time scales and attributes of the aquifer systems. This report describes several methods and indicators for presenting differing aspects of ground-water conditions using water-level observations in existing data-sets. The indicators of ground-water conditions developed in this study include areas experiencing water-level decline and water-level rise, recent trends in ground-water levels, and current depth to ground water. The computer programs written to create these indicators of ground-water conditions and display them in an interactive geographic information systems (GIS) format are explained and results illustrated through analyses of ground-water conditions for selected alluvial basins in the Lower Colorado River Basin in Arizona.
Meyer, Walter J
2006-01-01
Meyer''s Geometry and Its Applications, Second Edition, combines traditional geometry with current ideas to present a modern approach that is grounded in real-world applications. It balances the deductive approach with discovery learning, and introduces axiomatic, Euclidean geometry, non-Euclidean geometry, and transformational geometry. The text integrates applications and examples throughout and includes historical notes in many chapters. The Second Edition of Geometry and Its Applications is a significant text for any college or university that focuses on geometry''s usefulness in other disciplines. It is especially appropriate for engineering and science majors, as well as future mathematics teachers.* Realistic applications integrated throughout the text, including (but not limited to): - Symmetries of artistic patterns- Physics- Robotics- Computer vision- Computer graphics- Stability of architectural structures- Molecular biology- Medicine- Pattern recognition* Historical notes included in many chapters...
Thermodynamic Geometry and Extremal Black Holes in String Theory
Sarkar, Tapobrata; Tiwari, Bhupendra Nath
2008-01-01
We study a generalisation of thermodynamic geometry to degenerate quantum ground states at zero temperatures exemplified by charged extremal black holes in type II string theories. Several examples of extremal charged black holes with non degenerate thermodynamic geometries and finite but non zero state space scalar curvatures are established. These include black holes described by D1-D5-P and D2-D6-NS5-P brane systems and also two charged small black holes in Type II string theories. We also explore the modifications to the state space geometry and the scalar curvature due to the higher derivative contributions and string loop corrections as well as an exact entropy expression from quantum information theory. Our construction describes state space geometries arising out of a possible limiting thermodynamic characterisation of degenerate quantum ground states at zero temperatures.
The ground electronic state of KCs studied by Fourier transform spectroscopy
Ferber, R.; Klincare, I.; Nikolayeva, O.; Tamanis, M.; Knöckel, H.; Tiemann, E.; Pashov, A.
2008-06-01
We present here the first analysis of laser induced fluorescence (LIF) of the KCs molecule obtaining highly accurate data and perform a direct potential construction for the X 1Σ+ ground state in a wide range of internuclear distances. KCs molecules were produced by heating a mixture of K and Cs metals in a heat pipe at a temperature of about 270 °C. KCs fluorescence was induced by different laser sources: the 454.5, 457.9, 465.8, and 472.7 nm lines of an Ar+ laser, a dye laser with Rhodamine 6G dye (excitation at around 16 870 cm-1), and 850 and 980 nm diode lasers (11 500-11 900 and 10 200-10 450 cm-1 tuning ranges, respectively). The LIF to the ground state was recorded by a Bruker IFS-125HR Fourier transform spectrometer with a spectral resolution of 0.03 cm-1. Particularly, by applying the 850 nm laser diode we were able to observe LIF progressions to very high vibrational levels of the ground state close to the dissociation limit. The present data field contains 7226 term values for the ground state X 1Σ+ and covers a range from v''=0 to 97 with J'' varying from 12 to 209. More than 10 000 fluorescence lines were used to fit the ground state potential energy curve via the inverted perturbation approach procedure. The present empirical potential extends up to approximately 12.6 A˚ and covers more than 99% of the potential well depth, it describes most of the spectral lines with an accuracy of about 0.003 cm-1 and yields a dissociation energy of 4069.3+/-1.5 cm-1 for the ground state X 1Σ+. First observations of the triplet ground state a 3Σ+ of KCs are presented, and preliminary values of few main molecular constants could be derived.
Mandrà, Salvatore; Zhu, Zheng; Katzgraber, Helmut G.
2017-02-01
We study the performance of the D-Wave 2X quantum annealing machine on systems with well-controlled ground-state degeneracy. While obtaining the ground state of a spin-glass benchmark instance represents a difficult task, the gold standard for any optimization algorithm or machine is to sample all solutions that minimize the Hamiltonian with more or less equal probability. Our results show that while naive transverse-field quantum annealing on the D-Wave 2X device can find the ground-state energy of the problems, it is not well suited in identifying all degenerate ground-state configurations associated with a particular instance. Even worse, some states are exponentially suppressed, in agreement with previous studies on toy model problems [New J. Phys. 11, 073021 (2009), 10.1088/1367-2630/11/7/073021]. These results suggest that more complex driving Hamiltonians are needed in future quantum annealing machines to ensure a fair sampling of the ground-state manifold.
Ground-Based Gas-Liquid Flow Research in Microgravity Conditions: State of Knowledge
McQuillen, J.; Colin, C.; Fabre, J.
1999-01-01
During the last decade, ground-based microgravity facilities have been utilized in order to obtain predictions for spacecraft system designers and further the fundamental understanding of two-phase flow. Although flow regime, pressure drop and heat transfer coefficient data has been obtained for straight tubes and a limited number of fittings, measurements of the void fraction, film thickness, wall shear stress, local velocity and void information are also required in order to develop general mechanistic models that can be utilized to ascertain the effects of fluid properties, tube geometry and acceleration levels. A review of this research is presented and includes both empirical data and mechanistic models of the flow behavior.
Ground State Transitions in Vertically Coupled Four-Layer Single Electron Quantum Dots
Institute of Scientific and Technical Information of China (English)
WANGAn-Mei; XIEWen-Fang
2005-01-01
We study a four-electron system in a vertically coupled four-layer quantum dot under a magnetic field by the exact diagonalization of the Hamiltonian matr/x. We find that discontinuous ground-state energy transitions are induced by an external magnetic field. We find that dot-dot distance and electron-electron interaction strongly affect the low-lying states of the coupled quantum dots. The inter-dot correlation leads to some sequences of possible disappearances of ground state transitions, which are present for uncoupled dots.
Ground State Transitions in Vertically Coupled Four-Layer Single Electron Quantum Dots
Institute of Scientific and Technical Information of China (English)
WANG An-Mei; XIE Wen-Fang
2005-01-01
We study a four-electron system in a vertically coupled four-layer quantum dot under a magnetic field by the exact diagonalization of the Hamiltonian matrix. We find that discontinuous ground-state energy transitions are induced by an external magnetic field. We find that dot-dot distance and electron-electron interaction strongly affect the low-lying states of the coupled quantum dots. The inter-dot correlation leads to some sequences of possible disappearances of ground state transitions, which are present for uncoupled dots.
Vacuum polarization in the ground states of bi-muonic helium atoms
Frolov, Alexei M.
2004-11-01
The energies and bound-state properties of the bi-muonic helium-3 and helium-4 atoms in their ground 11(S = 0)-states are determined to very high accuracy. It is shown that the lowest order QED (and relativistic) effects play a significantly larger role in the case of bi-muonic 3Heμ2 and 4Heμ2 atoms than in the two-electron He-atoms. In particular, the effect of vacuum polarization and corresponding energy shifts for the ground 11(S = 0)-states in the bi-muonic helium-3 and helium-4 atoms have been evaluated.
Spin-Orbit Coupling Controlled J =3 /2 Electronic Ground State in 5 d3 Oxides
Taylor, A. E.; Calder, S.; Morrow, R.; Feng, H. L.; Upton, M. H.; Lumsden, M. D.; Yamaura, K.; Woodward, P. M.; Christianson, A. D.
2017-05-01
Entanglement of spin and orbital degrees of freedom drives the formation of novel quantum and topological physical states. Here we report resonant inelastic x-ray scattering measurements of the transition metal oxides Ca3 LiOsO6 and Ba2 YOsO6 , which reveals a dramatic spitting of the t2 g manifold. We invoke an intermediate coupling approach that incorporates both spin-orbit coupling and electron-electron interactions on an even footing and reveal that the ground state of 5 d3-based compounds, which has remained elusive in previously applied models, is a novel spin-orbit entangled J =3 /2 electronic ground state. This work reveals the hidden diversity of spin-orbit controlled ground states in 5 d systems and introduces a new arena in the search for spin-orbit controlled phases of matter.
Exact many-electron ground states on the diamond Hubbard chain
Gulacsi, Zsolt; Kampf, Arno; Vollhardt, Dieter
2008-03-01
Exact ground states of interacting electrons on the diamond Hubbard chain in a magnetic field are constructed which exhibit a wide range of properties such as flat-band ferromagnetism, correlation induced metallic, half-metallic, or insulating behavior [1]. The properties of these ground states can be tuned by changing the magnetic flux, local potentials, or electron density.The results show that the studied simple one-dimensional structure displays remarkably complex physical properties. The virtue of tuning different ground states through external parameters points to new possibilities for the design of electronic devices which can switch between insulating or conducting and nonmagnetic or (fully or partially spin polarized) ferromagnetic states, open new routes for the design of spin-valve devices and gate induced ferromagnetism. [1] Z. Gulacsi, A. Kampf, D. Vollhardt, Phys. Rev. Lett. 99, 026404(2007).
Ground-state energy of the q-state Potts model: The minimum modularity.
Lee, J S; Hwang, S; Yeo, J; Kim, D; Kahng, B
2014-11-01
A wide range of interacting systems can be described by complex networks. A common feature of such networks is that they consist of several communities or modules, the degree of which may quantified as the modularity. However, even a random uncorrelated network, which has no obvious modular structure, has a finite modularity due to the quenched disorder. For this reason, the modularity of a given network is meaningful only when it is compared with that of a randomized network with the same degree distribution. In this context, it is important to calculate the modularity of a random uncorrelated network with an arbitrary degree distribution. The modularity of a random network has been calculated [Reichardt and Bornholdt, Phys. Rev. E 76, 015102 (2007)PLEEE81539-375510.1103/PhysRevE.76.015102]; however, this was limited to the case whereby the network was assumed to have only two communities, and it is evident that the modularity should be calculated in general with q(≥2) communities. Here we calculate the modularity for q communities by evaluating the ground-state energy of the q-state Potts Hamiltonian, based on replica symmetric solutions assuming that the mean degree is large. We found that the modularity is proportional to 〈sqrt[k]〉/〈k〉 regardless of q and that only the coefficient depends on q. In particular, when the degree distribution follows a power law, the modularity is proportional to 〈k〉^{-1/2}. Our analytical results are confirmed by comparison with numerical simulations. Therefore, our results can be used as reference values for real-world networks.
Democratic Republic of Congo A Fertile Ground for Instability in the Great Lakes Region States
2017-06-09
DEMOCRATIC REPUBLIC OF CONGO-A FERTILE GROUND FOR INSTABILITY IN THE GREAT LAKES REGION STATES A thesis presented to the Faculty of...From - To) AUG 2016 – JUNE 2017 4. TITLE AND SUBTITLE Democratic Republic of Congo-A Fertile Ground for Instability in the Great Lakes Region ...caused instability and chaos in the eastern provinces of the Congo, known as the Great Lakes Region . The DRC holds a strategic geographical position
Chiral extrapolations and strangeness in the baryon ground states
Lutz, Matthias F M
2013-01-01
We review the quark-mass dependence of the baryon octet and decuplet masses as obtained from recent lattice simulations of the BMW, PACS-CS, LHPC, HSC and QCDSF-UKQCD groups. Our discussion relies on the relativistic chiral Lagrangian and large-$N_c$ sum rule estimates of the counter terms relevant for the baryon masses at N$^3$LO. A partial summation is implied by the use of physical baryon and meson masses in the one-loop contributions to the baryon self energies. In our analysis the physical masses are reproduced exactly by means of a suitable set of linear constraints. A quantitative and simultaneous description of all lattice results is achieved in terms of a six parameter fit, where the symmetry conserving counter term that are relevant at N$^3$LO are not yet being used. For pion masses larger than 300 MeV there appears to be an approximate linear pion-mass dependence of all octet and decuplet baryon masses. We discuss the pion- and strangeness sigma terms of the baryon octet states.
Joshi, Sunita; Pant, Debi D.
2012-06-01
Ground and excited state dipole moments of probe quinine sulphate (QS) was obtained using Solvatochromic shift method. Higher dipole moment is observed for excited state as compared to the ground state which is attributed to the higher polarity of excited state.
Structural Distortion Stabilizing the Antiferromagnetic and Semiconducting Ground State of BaMn2As2
Directory of Open Access Journals (Sweden)
Ekkehard Krüger
2016-09-01
Full Text Available We report evidence that the experimentally found antiferromagnetic structure as well as the semiconducting ground state of BaMn 2 As 2 are caused by optimally-localized Wannier states of special symmetry existing at the Fermi level of BaMn 2 As 2 . In addition, we find that a (small tetragonal distortion of the crystal is required to stabilize the antiferromagnetic semiconducting state. To our knowledge, this distortion has not yet been established experimentally.
Van der Waals potential and vibrational energy levels of the ground state radon dimer
Sheng, Xiaowei; Qian, Shifeng; Hu, Fengfei
2017-08-01
In the present paper, the ground state van der Waals potential of the Radon dimer is described by the Tang-Toennies potential model, which requires five essential parameters. Among them, the two dispersion coefficients C6 and C8 are estimated from the well determined dispersion coefficients C6 and C8 of Xe2. C10 is estimated by using the approximation equation that C6C10 / C82 has an average value of 1.221 for all the rare gas dimers. With these estimated dispersion coefficients and the well determined well depth De and Re the Born-Mayer parameters A and b are derived. Then the vibrational energy levels of the ground state radon dimer are calculated. 40 vibrational energy levels are observed in the ground state of Rn2 dimer. The last vibrational energy level is bound by only 0.0012 cm-1.
Evidence for a gapped spin-liquid ground state in a kagome Heisenberg antiferromagnet.
Fu, Mingxuan; Imai, Takashi; Han, Tian-Heng; Lee, Young S
2015-11-06
The kagome Heisenberg antiferromagnet is a leading candidate in the search for a spin system with a quantum spin-liquid ground state. The nature of its ground state remains a matter of active debate. We conducted oxygen-17 single-crystal nuclear magnetic resonance (NMR) measurements of the spin-1/2 kagome lattice in herbertsmithite [ZnCu3(OH)6Cl2], which is known to exhibit a spinon continuum in the spin excitation spectrum. We demonstrated that the intrinsic local spin susceptibility χ(kagome), deduced from the oxygen-17 NMR frequency shift, asymptotes to zero below temperatures of 0.03J, where J ~ 200 kelvin is the copper-copper superexchange interaction. Combined with the magnetic field dependence of χ(kagome) that we observed at low temperatures, these results imply that the kagome Heisenberg antiferromagnet has a spin-liquid ground state with a finite gap.
Ground State Properties of the 1/2 Flux Harper Hamiltonian
Kennedy, Colin; Burton, William Cody; Chung, Woo Chang; Ketterle, Wolfgang
2015-05-01
The Harper Hamiltonian describes the motion of charged particles in an applied magnetic field - the spectrum of which exhibits the famed Hofstadter's butterfly. Recent advances in driven optical lattices have made great strides in simulating nontrivial Hamiltonians, such as the Harper model, in the time-averaged sense. We report on the realization of the ground state of bosons in the Harper Hamiltonian for 1/2 flux per plaquette utilizing a tilted two-dimensional lattice with laser assisted tunneling. We detail progress in studying various ground state properties of the 1/2 flux Harper Hamiltonian including ground state degeneracies, gauge-dependent observables, effects of micromotion, adiabatic loading schemes, and emergence and decay of coherence. Additionally, we describe prospects for flux rectification using a period-tripled superlattice and generalizations to three dimensions. MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, Department of Physics, Massachusetts Institute of Technology.
Tree based machine learning framework for predicting ground state energies of molecules
Himmetoglu, Burak
2016-10-01
We present an application of the boosted regression tree algorithm for predicting ground state energies of molecules made up of C, H, N, O, P, and S (CHNOPS). The PubChem chemical compound database has been incorporated to construct a dataset of 16 242 molecules, whose electronic ground state energies have been computed using density functional theory. This dataset is used to train the boosted regression tree algorithm, which allows a computationally efficient and accurate prediction of molecular ground state energies. Predictions from boosted regression trees are compared with neural network regression, a widely used method in the literature, and shown to be more accurate with significantly reduced computational cost. The performance of the regression model trained using the CHNOPS set is also tested on a set of distinct molecules that contain additional Cl and Si atoms. It is shown that the learning algorithms lead to a rich and diverse possibility of applications in molecular discovery and materials informatics.
Tree based machine learning framework for predicting ground state energies of molecules
Himmetoglu, Burak
2016-01-01
We present an application of the boosted regression tree algorithm for predicting ground state energies of molecules made up of C, H, N, O, P, and S (CHNOPS). The PubChem chemical compound database has been incorporated to construct a dataset of 16,242 molecules, whose electronic ground state energies have been computed using density functional theory. This dataset is used to train the boosted regression tree algorithm, which allows a computationally efficient and accurate prediction of molecular ground state energies. Predictions from boosted regression trees are compared with neural network regression, a widely used method in the literature, and shown to be more accurate with significantly reduced computational cost. The performance of the regression model trained using the CHNOPS set is also tested on a set of distinct molecules that contain additional Cl and Si atoms. It is shown that the learning algorithms lead to a rich and diverse possibility of applications in molecular discovery and materials inform...
Ground-state Properties of Inhomogeneous Graphene Sheets
Polini, Marco
2009-03-01
.S. Novoselov, and A.K. Geim, arXiv:0709.1163v2 (2007).[0pt] [2] M. Polini, A. Tomadin, R. Asgari, and A.H. MacDonald, Phys. Rev. B 78, 115426 (2008).[0pt] [3] Y. Barlas, T. Pereg-Barnea, M. Polini, R. Asgari, and A.H. MacDonald, Phys. Rev. Lett. 98, 236601 (2007); M. Polini, R. Asgari, Y. Barlas, T. Pereg-Barnea, and A.H. MacDonald, Solid State Commun. 143, 58 (2007). [0pt] [4] E.H. Hwang, B.Y.-K. Hu, and S. Das Sarma, Phys. Rev. Lett. 99, 226801 (2007).[0pt] [5] J. Martin, N. Akerman, G. Ulbricht, T. Lohmann, J.H. Smet, K. von Klitzing, and A. Yacoby, Nature Phys. 4, 144 (2008).[0pt] [6] V.W. Brar, Y. Zhang, C. Girit, F. Wang, A. Zettl, and M. Crommie, Bull. Am. Phys. Soc. 53 (2), 443 (2008).
Fourier-transform spectroscopy of Sr2 and revised ground-state potential
Stein, A.; Knöckel, H.; Tiemann, E.
2008-10-01
Precise potentials for the ground-state XΣg+1 and the minimum region of the excited state 2Σu+1 of Sr2 are derived by high-resolution Fourier-transform spectroscopy of fluorescence progressions from single-frequency laser excitation of Sr2 produced in a heat pipe at 950°C . A change of the rotational assignment by four units compared to an earlier work [G. Gerber , J. Chem. Phys. 81, 1538 (1984)] is needed for a consistent description leading to a significant shift of the potentials toward longer interatomic distances. The huge amount of ground-state data derived for the three different isotopomers Sr288 , Sr86Sr88 , and Sr87Sr88 (almost 60% of all excisting bound rovibrational ground-state levels for the isotopomer Sr288 ) fixes this assignment beyond a doubt. The presented ground-state potential is derived from the observed transitions for the radial region from 4to11Å ( 9cm-1 below the asymptote) and is extended to the long-range region by the use of theoretical dispersion coefficients together with already available photoassociation data. New estimations of the scattering lengths for the complete set of isotopic combinations are derived by mass scaling with the derived potential. The data set for the excited state 2Σu+1 was sufficient to derive a potential energy curve around the minimum.
Ground-State Transition in a Two-Dimensional Frenkel-Kontorova Model
Institute of Scientific and Technical Information of China (English)
YUAN Xiao-Ping; ZHENG Zhi-Gang
2011-01-01
The ground state of a generalized Frenkel-Kontorova model with a transversaJ degree of freedom is studied. When the coupling strength, K, and the frequency of & single-Atom vibration in the transversaJ direction, ωou are increased, the ground state of the model undergoes a transition from a two-dimensional configuration to a one-dimensional one. This transition can manifest in different ways. Furthermore, we find that the prerequisite of a two-dimensionai ground state is θ≠1//q.%The ground state of a generalized Frenkel-Kontorova model with a transversal degree of freedom is studied.When the coupling strength,K,and the frequency of a single-atom vibration in the transversal direction,ωoy,are increased,the ground state of the model undergoes a transition from a two-dimensional configuration to a one-dimensional one.This transition can manifest in different ways.Furthermore,we find that the prerequisite of a two-dimensional ground state is θ ≠ 1/q.In recent years,the Frenkel-Kontorova (FK) model has been applied to a variety of physical systems,such as adsorbed monolayers,[1,2] Josephsonjunction arrays,[3-5] tribology[6-8] and charge-density waves.[9,10] Experimental and large-scale simulation data at the nanoscale have become available,and more complicated FK-type models have been investigated using simulations of molecular dynamics.[11
Kohn, W.
1983-01-01
It is shown that if n(r) is the discrete density on a lattice (enclosed in a finite box) associated with a nondegenerate ground state in an external potential v(r) (i.e., is 'v-representable'), then the density n(r) + mu(r), with m(r) arbitrary (apart from trivial constraints) and mu small enough, is also associated with a nondegenerate ground state in an external potential v'(r) near v(r); i.e., n(r) + m(r) is also v-representable. Implications for the Hohenberg-Kohn variational principle and the Kohn-Sham equations are discussed.
First-principles prediction of a ground state crystal structure of magnesium borohydride.
Ozolins, V; Majzoub, E H; Wolverton, C
2008-04-04
Mg(BH(4))(2) contains a large amount of hydrogen by weight and by volume, but its promise as a candidate for hydrogen storage is dependent on the currently unknown thermodynamics of H2 release. Using first-principles density-functional theory calculations and a newly developed prototype electrostatic ground state search strategy, we predict a new T=0 K ground state of Mg(BH(4))(2) with I4[over ]m2 symmetry, which is 5 kJ/mol lower in energy than the recently proposed P6(1) structure. The calculated thermodynamics of H(2) release are within the range required for reversible storage.
Ground state atomic oxygen in high-power impulse magnetron sputtering: a quantitative study
Britun, Nikolay; Belosludtsev, Alexandr; Silva, Tiago; Snyders, Rony
2017-02-01
The ground state density of oxygen atoms in reactive high-power impulse magnetron sputtering discharges has been studied quantitatively. Both time-resolved and space-resolved measurements were conducted. The measurements were performed using two-photon absorption laser-induced fluorescence (TALIF), and calibrated by optical emission actinometry with multiple Ar emission lines. The results clarify the dynamics of the O ground state atoms in the discharge afterglow significantly, including their propagation and fast decay after the plasma pulse, as well as the influence of gas pressure, O2 admixture, etc.
Preparing ground States of quantum many-body systems on a quantum computer.
Poulin, David; Wocjan, Pawel
2009-04-03
Preparing the ground state of a system of interacting classical particles is an NP-hard problem. Thus, there is in general no better algorithm to solve this problem than exhaustively going through all N configurations of the system to determine the one with lowest energy, requiring a running time proportional to N. A quantum computer, if it could be built, could solve this problem in time sqrt[N]. Here, we present a powerful extension of this result to the case of interacting quantum particles, demonstrating that a quantum computer can prepare the ground state of a quantum system as efficiently as it does for classical systems.
Traces of Lorentz symmetry breaking in a hydrogen atom at ground state
Borges, L. H. C.; Barone, F. A.
2016-02-01
Some traces of a specific Lorentz symmetry breaking scenario in the ground state of the hydrogen atom are investigated. We use standard Rayleigh-Schrödinger perturbation theory in order to obtain the corrections to the ground state energy and the wave function. It is shown that an induced four-pole moment arises, due to the Lorentz symmetry breaking. The model considered is the one studied in Borges et al. (Eur Phys J C 74:2937, 2014), where the Lorentz symmetry is broken in the electromagnetic sector.
Ub-library of Atomic Masses and Nuclear Ground States Deformations (CENPL.AMD)
Institute of Scientific and Technical Information of China (English)
2001-01-01
The atomic mass is one of basic data of a nuclear. There are the atomic masses in all nuclear reaction model formulas and motion equations. For any reaction calculations atomic masses are basic data for getting binding energies or Q-values. In some applications, it is important also to have atomic masses even for exotic nuclei quite far from the valley of stability. In addition, nuclear ground state deformations and abundance values are also requisite in the nuclear data calculations. For this purpose, A data file on atomic masses and nuclear ground states deformations (AMD) were constructed, which
Expectation values of single-particle operators in the random phase approximation ground state
Kosov, Daniel S
2016-01-01
We developed a method for computing matrix elements of single-particle operators in the correlated random phase approximation ground state. Working with the explicit random phase approximation ground state wavefunction, we derived practically useful and simple expression for a molecular property in terms of random phase approximation amplitudes. The theory is illustrated by the calculation of molecular dipole moments. It is shown that Hartree-Fock based random phase approximation provides a systematic improvement of molecular dipole moment values in comparison to M{\\o}ller-Plesset second order perturbation theory and coupled cluster method for a considered set of molecules.
Stability of the electroweak ground state in the Standard Model and its extensions
Directory of Open Access Journals (Sweden)
Luca Di Luzio
2016-02-01
Full Text Available We review the formalism by which the tunnelling probability of an unstable ground state can be computed in quantum field theory, with special reference to the Standard Model of electroweak interactions. We describe in some detail the approximations implicitly adopted in such calculation. Particular attention is devoted to the role of scale invariance, and to the different implications of scale-invariance violations due to quantum effects and possible new degrees of freedom. We show that new interactions characterized by a new energy scale, close to the Planck mass, do not invalidate the main conclusions about the stability of the Standard Model ground state derived in absence of such terms.
Traces of Lorentz symmetry breaking in a Hydrogen atom at ground state
Borges, Luiz Henrique de Campos
2016-01-01
Some traces of a specific Lorentz symmetry breaking scenario in the ground state of the Hydrogen atom are investigated. It is used standard Rayleigh-Schr\\"odinger perturbation theory in order to obtain the corrections to the the ground state energy and wave function. It is shown that an induced four-pole moment arises, due to the Lorentz symmetry breaking. The model considered is the one studied in reference Eur. Phys. J. C {\\bf 74}, 2937 (2014), where the Lorentz symmetry is broken in the electromagnetic sector.
Boundedness and convergence of perturbed corrections for helium-like ions in ground states
Institute of Scientific and Technical Information of China (English)
Zhao Yun-Hui; Hai Wen-Hua; Zhao Cheng-Lin; Luo Xiao-Bing
2008-01-01
Applying the improved Rayleigh-Schr(o)dinger perturbation theory based on an integral equation to helium-like ions in ground states and treating electron correlations as perturbations,we obtain the second-order corrections to wavefunctions consisting of a few terms and the third-order corrections to energicity.It is demonstrated that the corrected wavefunctions are bounded and quadratically integrable,and the corresponding perturbation series is convergent.The results clear off the previous distrust for the convergence in the quantum perturbation theory and show a reciprocal development on the quantum perturbation problem of the ground state helium-like systems.
Singlet Ground State Magnetism: III Magnetic Excitons in Antiferromagnetic TbP
DEFF Research Database (Denmark)
Knorr, K.; Loidl, A.; Kjems, Jørgen
1981-01-01
The dispersion of the lowest magnetic excitations of the singlet ground state system TbP has been studied in the antiferromagnetic phase by inelastic neutron scattering. The magnetic exchange interaction and the magnetic and the rhombohedral molecular fields have been determined.......The dispersion of the lowest magnetic excitations of the singlet ground state system TbP has been studied in the antiferromagnetic phase by inelastic neutron scattering. The magnetic exchange interaction and the magnetic and the rhombohedral molecular fields have been determined....
Ground State Properties of Superheavy Nuclei in Macroscopic-Microscopic Model
Institute of Scientific and Technical Information of China (English)
ZHI Qi-Jun; REN Zhong-Zhou; ZHANG Xiao-Ping; ZHENG Qiang
2008-01-01
The ground state properties of superheavy nuclei are systematically calculated by the macroscopic-microscopic (MM) model with the Nilsson potential The calculations well produced the ground state binding energies,a-decay energies,and half lives of superheavy nuclei.The calculated results are systematically compared with available experimental data.The calculated results are also compared with theoretical results from other MM models and from relativistic mean-field model.The calculations and comparisons show that the MM model is reliable in superheavy region and that the MM model results are not very sensitive to the choice of microscopic single-particle potential.
Traces of Lorentz symmetry breaking in a hydrogen atom at ground state
Energy Technology Data Exchange (ETDEWEB)
Borges, L.H.C. [Universidade Federal do ABC, Centro de Ciencias Naturais e Humanas, Santo Andre, SP (Brazil); Barone, F.A. [IFQ-Universidade Federal de Itajuba, Itajuba, MG (Brazil)
2016-02-15
Some traces of a specific Lorentz symmetry breaking scenario in the ground state of the hydrogen atom are investigated. We use standard Rayleigh-Schroedinger perturbation theory in order to obtain the corrections to the ground state energy and the wave function. It is shown that an induced four-pole moment arises, due to the Lorentz symmetry breaking. The model considered is the one studied in Borges et al. (Eur Phys J C 74:2937, 2014), where the Lorentz symmetry is broken in the electromagnetic sector. (orig.)
Theoretical Studies on Thermal Decomposition of Benzoyl Peroxide in Ground State
Institute of Scientific and Technical Information of China (English)
SUN Cheng-ke; YANG Si-ya; LIN Xue-fei; MA Si-yu; LI Zong-he
2003-01-01
Systematic studies of the thermal decomposition mechanism of benzoyl peroxide(BPO) in ground state, leading to various intermediates, products and the potential energy surface(PES) of possible dissociation reactions were made computationally. The structures of the transition states and the activation energies for all the paths causing the formation of the reaction products mentioned above were calculated by the AM1 semi-empirical method. This method is shown to to be one predict correctly the preferred pathway for the title reaction. It has been found that in ground state, the thermal decomposition of benzoyl peroxide has two kinds of paths. The first pathway PhC(O)O-OC(O)Ph→PhC(O)O*→Ph*+CO2 produces finally phenyl radicals and carbon dioxide. And the second pathway PhC(O)OO-C(O)Ph→PhC(O)OO*+PhC(O)*→PhC(O)*+O2→Ph*+CO+O2, via which the reaction takes place only in two steps, produces oxygen and PhC(O)* radicals, and the further thermal dissociation of PhC(O)* is quite difficult because of the high activation energy in ground state. The calculated activation energies and reaction enthalpies are in good agreement with the experimental values. The research results also show that also the thermal dissociation process of the two bonds or the three bonds for the benzoyl peroxide doesn′t take place in ground state.
Seif, W M; Refaie, A I
2015-01-01
The ground-state spin and parity of a formed daughter in the radioactive Alpha-emitter is expected to influence the preformation probability of the Alpha and daughter clusters inside it. We investigate the Alpha and daughter preformation probability inside odd-A and doubly-odd radioactive nuclei when the daughter and parent are of different spin and/or parity. We consider only the ground-state to ground-state unfavored decays. This is to extract precise information about the effect of the difference in the ground states spin-parity of the involved nuclei far away any influences from the excitation energy if the decays are coming from isomeric states. The calculations are done for 161 Alpha-emitters, with Z=65-112 and N=84-173, in the framework of the extended cluster model, with WKB penetrability and assault frequency. We used a Hamiltonian energy density scheme based on Skyrme-SLy4 interaction to compute the interaction potential. The Alpha plus cluster preformation probability is extracted from the calculat...
Systematic study of α preformation probability of nuclear isomeric and ground states
Sun, Xiao-Dong; Wu, Xi-Jun; Zheng, Bo; Xiang, Dong; Guo, Ping; Li, Xiao-Hua
2017-01-01
In this paper, based on the two-potential approach combining with the isospin dependent nuclear potential, we systematically compare the α preformation probabilities of odd-A nuclei between nuclear isomeric states and ground states. The results indicate that during the process of α particle preforming, the low lying nuclear isomeric states are similar to ground states. Meanwhile, in the framework of single nucleon energy level structure, we find that for nuclei with nucleon number below the magic numbers, the α preformation probabilities of high-spin states seem to be larger than low ones. For nuclei with nucleon number above the magic numbers, the α preformation probabilities of isomeric states are larger than those of ground states. Supported by National Natural Science Foundation of China (11205083), Construct Program of Key Discipline in Hunan Province, Research Foundation of Education Bureau of Hunan Province, China (15A159), Natural Science Foundation of Hunan Province, China (2015JJ3103, 2015JJ2123), Innovation Group of Nuclear and Particle Physics in USC, Hunan Provincial Innovation Foundation for Postgraduate (CX2015B398)
Structures of 17F and 17O, 17Ne and 17N in the Ground State and the First Excited State
Institute of Scientific and Technical Information of China (English)
张虎勇; 沈文庆; 任中洲; 马余刚; 陈金根; 蔡翔舟; 卢照辉; 钟晨; 郭威; 魏义彬; 周星飞; 马国亮; 王鲲
2003-01-01
The structures of two couples of mirror nuclei 17 F and 17 O, 17 Ne and 17 N in the ground state and in the first excited state are investigated using the relativistic mean-field approach. Two-proton halo in 17Ne in the first excited state and in the ground state and two-neutron halo in 17N in the first excited state are suggested.Meanwhile, one-proton halo in 17 F in the first excited state and one-neutron halo in 17 O in the first excited state are also suggested. The skin structure appears in 17F and 17N in the ground state.
Generalized isotropic Lipkin-Meshkov-Glick models: ground state entanglement and quantum entropies
Carrasco, José A.; Finkel, Federico; González-López, Artemio; Rodríguez, Miguel A.; Tempesta, Piergiulio
2016-03-01
We introduce a new class of generalized isotropic Lipkin-Meshkov-Glick models with \\text{su}(m+1) spin and long-range non-constant interactions, whose non-degenerate ground state is a Dicke state of \\text{su}(m+1) type. We evaluate in closed form the reduced density matrix of a block of L spins when the whole system is in its ground state, and study the corresponding von Neumann and Rényi entanglement entropies in the thermodynamic limit. We show that both of these entropies scale as alog L when L tends to infinity, where the coefficient a is equal to (m - k)/2 in the ground state phase with k vanishing \\text{su}(m+1) magnon densities. In particular, our results show that none of these generalized Lipkin-Meshkov-Glick models are critical, since when L\\to ∞ their Rényi entropy R q becomes independent of the parameter q. We have also computed the Tsallis entanglement entropy of the ground state of these generalized \\text{su}(m+1) Lipkin-Meshkov-Glick models, finding that it can be made extensive by an appropriate choice of its parameter only when m-k≥slant 3 . Finally, in the \\text{su}(3) case we construct in detail the phase diagram of the ground state in parameter space, showing that it is determined in a simple way by the weights of the fundamental representation of \\text{su}(3) . This is also true in the \\text{su}(m+1) case; for instance, we prove that the region for which all the magnon densities are non-vanishing is an (m + 1)-simplex in {{{R}}m} whose vertices are the weights of the fundamental representation of \\text{su}(m+1) .
The ground state of medium-heavy nuclei with non central forces
Fabrocini, A
1997-01-01
We study microscopically the ground state properties of 16O and 40Ca nuclei within correlated basis function theory. A truncated version of the realistic Urbana v14 (U14) potential, without momentum dependent terms, is adopted with state dependent correlations having spin, isospin and tensor components. Fermi hypernetted chain integral equations and single operator chain approximation are used to evaluate one- and two-body densities and ground state energy. The results are in good agreement with the available variational MonteCarlo data, providing a first substantial check for the accuracy of the cluster expansion method with state dependent correlations. The finite nuclei treatment of non central interactions and correlations has, at least, the same level of accuracy as in infinite nuclear matter. The binding energy for the full U14+TNI interaction is computed, addressing its small momentum dependent contributions in local density approximation. The nuclei are underbound by about 1 MeV per nucleon. Further e...
Laser cooling a neutral atom to the three-dimensional vibrational ground state of an optical tweezer
Kaufman, Adam M; Regal, Cindy A
2012-01-01
We report three-dimensional ground state cooling of a single neutral atom in an optical tweezer. After employing Raman sideband cooling for 33 ms, we measure via sideband spectroscopy a three-dimensional ground state occupation of ~90%. Ground state neutral atoms in optical tweezers will be instrumental in numerous quantum logic applications and for nanophotonic interfaces that require a versatile platform for storing, moving, and manipulating ultracold single neutral atoms.
Energy Technology Data Exchange (ETDEWEB)
Kleinlein, Claudia; Zheng, Shao-Liang; Betley, Theodore A.
2017-04-24
Three ferric dipyrromethene complexes featuring different ancillary ligands were synthesized by one electron oxidation of ferrous precursors. Four-coordinate iron complexes of the type (^{Ar}L)FeX_{2} [^{Ar}L = 1,9-(2,4,6-Ph_{3}C_{6}H_{2})_{2}-5-mesityldipyrromethene] with X = Cl or ^{t}BuO were prepared and found to be high-spin (S = 5/2), as determined by superconducting quantum interference device magnetometry, electron paramagnetic resonance, and ^{57}Fe Mössbauer spectroscopy. The ancillary ligand substitution was found to affect both ground state and excited properties of the ferric complexes examined. While each ferric complex displays reversible reduction and oxidation events, each alkoxide for chloride substitution results in a nearly 600 mV cathodic shift of the Fe^{III/II} couple. The oxidation event remains largely unaffected by the ancillary ligand substitution and is likely dipyrrin-centered. While the alkoxide substituted ferric species largely retain the color of their ferrous precursors, characteristic of dipyrrin-based ligand-to-ligand charge transfer (LLCT), the dichloride ferric complex loses the prominent dipyrrin chromophore, taking on a deep green color. Time-dependent density functional theory analyses indicate the weaker-field chloride ligands allow substantial configuration mixing of ligand-to-metal charge transfer into the LLCT bands, giving rise to the color changes observed. Furthermore, the higher degree of covalency between the alkoxide ferric centers is manifest in the observed reactivity. Delocalization of spin density onto the tert-butoxide ligand in (^{Ar}L)FeCl(O^{t}Bu) is evidenced by hydrogen atom abstraction to yield (^{Ar}L)FeCl and HOtBu in the presence of substrates containing weak C–H bonds, whereas the chloride (^{Ar}L)FeCl_{2} analogue does not react under these conditions.
Magnetostriction-driven ground-state stabilization in 2H perovskites
Porter, D. G.; Senn, M. S.; Khalyavin, D. D.; Cortese, A.; Waterfield-Price, N.; Radaelli, P. G.; Manuel, P.; zur-Loye, H.-C.; Mazzoli, C.; Bombardi, A.
2016-10-01
The magnetic ground state of Sr3A RuO6 , with A =(Li ,Na ) , is studied using neutron diffraction, resonant x-ray scattering, and laboratory characterization measurements of high-quality crystals. Combining these results allows us to observe the onset of long-range magnetic order and distinguish the symmetrically allowed magnetic models, identifying in-plane antiferromagnetic moments and a small ferromagnetic component along the c axis. While the existence of magnetic domains masks the particular in-plane direction of the moments, it has been possible to elucidate the ground state using symmetry considerations. We find that due to the lack of local anisotropy, antisymmetric exchange interactions control the magnetic order, first through structural distortions that couple to in-plane antiferromagnetic moments and second through a high-order magnetoelastic coupling that lifts the degeneracy of the in-plane moments. The symmetry considerations used to rationalize the magnetic ground state are very general and will apply to many systems in this family, such as Ca3A RuO6 , with A =(Li ,Na ) , and Ca3LiOsO6 whose magnetic ground states are still not completely understood.
On the ground state energy of the delta-function Fermi gas
Tracy, Craig A.; Widom, Harold
2016-10-01
The weak coupling asymptotics to order γ of the ground state energy of the delta-function Fermi gas, derived heuristically in the literature, is here made rigorous. Further asymptotics are in principle computable. The analysis applies to the Gaudin integral equation, a method previously used by one of the authors for the asymptotics of large Toeplitz matrices.
Patterns of the ground states in the presence of random interactions : Nucleon systems
Zhao, YM; Arima, A; Shimizu, N; Ogawa, K; Yoshinaga, N; Scholten, O
2004-01-01
We present our results on properties of ground states for nucleonic systems in the presence of random two-body interactions. In particular, we calculate probability distributions for parity, seniority, spectroscopic (i.e., in the laboratory frame) quadrupole moments, and discuss a clustering in the
Ground states for a modified capillary surface equation in weighted Orlicz-Sobolev space
Directory of Open Access Journals (Sweden)
Guoqing Zhang
2015-03-01
Full Text Available In this article, we prove a compact embedding theorem for the weighted Orlicz-Sobolev space of radially symmetric functions. Using the embedding theorem and critical points theory, we prove the existence of multiple radial solutions and radial ground states for the following modified capillary surface equation $$\\displaylines{ -\\operatorname{div}\\Big(\\frac{|\
Surface Gap Soliton Ground States for the Nonlinear Schr\\"{o}dinger Equation
Dohnal, Tomáš; Reichel, Wolfgang
2010-01-01
We consider the nonlinear Schr\\"{o}dinger equation $(-\\Delta +V(x))u = \\Gamma(x) |u|^{p-1}u$, $x\\in \\R^n$ with $V(x) = V_1(x) \\chi_{\\{x_1>0\\}}(x)+V_2(x) \\chi_{\\{x_10\\}}(x)+\\Gamma_2(x) \\chi_{\\{x_1<0\\}}(x)$ and with $V_1, V_2, \\Gamma_1, \\Gamma_2$ periodic in each coordinate direction. This problem describes the interface of two periodic media, e.g. photonic crystals. We study the existence of ground state $H^1$ solutions (surface gap soliton ground states) for $0<\\min \\sigma(-\\Delta +V)$. Using a concentration compactness argument, we provide an abstract criterion for the existence based on ground state energies of each periodic problem (with $V\\equiv V_1, \\Gamma\\equiv \\Gamma_1$ and $V\\equiv V_2, \\Gamma\\equiv \\Gamma_2$) as well as a more practical criterion based on ground states themselves. Examples of interfaces satisfying these criteria are provided. In 1D it is shown that, surprisingly, the criteria can be reduced to conditions on the linear Bloch waves of the operators $-\\tfrac{d^2}{dx^2} +V_1(x)$ an...
DEFF Research Database (Denmark)
Johnsen, Kristinn; Yngvason, Jakob
1996-01-01
and the electron number N tend to infinity with N/Z fixed, and the magnetic field B tends to infinity in such a way that B/Z4/3→∞. We have calculated electronic density profiles and ground-state energies for values of the parameters that prevail on neutron star surfaces and compared them with results obtained...
Effect of spin-orbit coupling on the ground state structure of mercury
Mishra, Vinayak; Gyanchandani, Jyoti; Chaturvedi, Shashank; Sikka, S. K.
2014-05-01
Near zero kelvin ground state structure of mercury is the body centered tetragonal (BCT) structure (β Hg). However, in all previously reported density functional theory (DFT) calculations, either the rhombohedral or the HCP structure has been found to be the ground state structure. Based on the previous calculations it was predicted that the correct treatment of the SO effects would improve the result. We have performed FPLAPW calculations, with and without inclusion of the SO coupling, for determining the ground state structure. These calculations determine rhombohedral structure as the ground state structure instead of BCT structure. The calculations, without inclusion of SO effect, predict that the energies of rhombohedral and BCT structures are very close to each other but the energy of rhombohedral structure is lower than that of BCT structure at ambient as well as high pressure. On the contrary, the SO calculations predict that though at ambient conditions the rhombohedral structure is the stable structure but on applying a pressure of 3.2 GPa, the BCT structure becomes stable. Hence, instead of predicting the stability of BCT structure at zero pressure, the SO calculations predict its stability at 3.2 GPa. This small disagreement is expected when the energy differences between the structures are small.
Complete $\\alpha^6\\,m$ corrections to the ground state of H$_2$
Puchalski, Mariusz; Czachorowski, Pawel; Pachucki, Krzysztof
2016-01-01
We perform the calculation of all relativistic and quantum electrodynamic corrections of the order of $\\alpha^6\\,m$ to the ground electronic state of a hydrogen molecule and present improved results for the dissociation and the fundamental transitions energies. These results open the window for the high-precision spectroscopy of H$_2$ and related low-energy tests of fundamental interactions.
A New Method for the Atomic Ground-State Energy in the Screened Coulomb Potential
Institute of Scientific and Technical Information of China (English)
YU Peng-Peng; GUO Hua
2001-01-01
The new method proposed recently by Friedberg,Lee and Zhao is applied to the derivation of the atomic ground-state energy with the inclusion of the screening effect.The present results are compared with those obtained in the pure Coulomb potential and by the variational approach.The overall good results are obtained with this new method.``
Ground-state and Pairing Properties of Pr Isotopes in RMF Theory
Institute of Scientific and Technical Information of China (English)
2002-01-01
The ground-state and pairing properties of Pr (Z=59) isotopes have been investigated in therelativistic mean-field (RMF). The pairing correlation is studied in Bardeen-Cooper-Schrieffer (BCS) approximation and the pairingforces are taken to be isospin dependent. The ’blocking’ method is adopted to deal with unpaired odd
A Simple Volcano Potential with an Analytic, Zero-Energy, Ground State
Nieto, Michael Martin
2000-01-01
We describe a simple volcano potential, which is supersymmetric and has an analytic, zero-energy, ground state. (The KK modes are also analytic.) It is an interior harmonic oscillator potential properly matched to an exterior angular momentum-like tail. Special cases are given to elucidate the physics, which may be intuitively useful in studies of higher-dimensional gravity.
Theoretical study of the ground state of (EDO-TTF)(2)PF6
Linker, Gerrit-Jan; van Duijnen, Piet Th.; van Loosdrecht, Paul H.M.; Broer, Ria
2015-01-01
In this paper we present a theoretical study of the nature of the ground state of the (EDO-TTF)(2)PF6 charge transfer salt by using ab initio quantum chemical theory for clusters in vacuum, for embedded clusters and for the periodic system. Exemplary for other organic charge transfer systems, we sho
The ground state energy of the mean field spin glass model
Koukiou, Flora
2008-01-01
From the study of a functional equation of Gibbs measures we calculate the limiting free energy of the Sherrington-Kirkpatrick spin glass model at a particular value of (low) temperature. This implies the following lower bound for the ground state energy $\\epsilon_0$ \\[\\epsilon_0\\geq -0.7833...,\\] close to the replica symmetry breaking and numerical simulations values.
Soluble and stable heptazethrenebis(dicarboximide) with a singlet open-shell ground state
Sun, Zhe
2011-08-10
A soluble and stable heptazethrene derivative was synthesized and characterized for the first time. This molecule exhibits a singlet biradical character in the ground state, which is the first case among zethrene homologue series. Exceptional stability of this heptazethrenebis(dicarboximide) raises the likelihood of its practical applications in materials science. © 2011 American Chemical Society.
Ab initio organic chemistry : a survey of ground- and excited states and aromaticity
Havenith, R.W.A.
2001-01-01
This thesis describes the application of quantum mechanical methods on organic chemistry. The ground- and excited states of functionalized oligo(cyclohexylidenes) have been explored as in function of chain length, conformation and substitution. VB theory has been used to study the effect of cyc
Transient state of polarization in optical ground wire caused by lightning and impulse current
Kurono, Masahiro; Isawa, K.; Kuribara, Masayuki
1996-08-01
This paper describes a transient state of polarization in an optical ground wire (OPGW) theoretically, experimentally and with field measurements in lightning conditions, which is considered one of the fastest phenomena of polarization fluctuations in the natural environment. These characteristics will be required for optical coherent communication for utilities in future and for application to sensing of lightning with OPGW.
Positive and ground state solutions for the critical Klein-Gordon-Maxwell system with potentials
Carriao, Paulo C; Miyagaki, Olimpio H
2010-01-01
In this paper we study a class of Klein-Gordon-Maxwell system when the nonlinearity exhibits critical growth. First we prove both existence and ground state solutions for this system with a periodic potencial V, and then we show the existence in the case that a nonperiodic potencial V is introduced.
The magnetic structure on the ground state of the equilateral triangular spin tube
Matsui, Kazuki; Goto, Takayuki; Manaka, Hirotaka; Miura, Yoko
2016-12-01
The ground state of the frustrated equilateral triangular spin tube CsCrF4 is still hidden behind a veil though NMR spectrum broaden into 2 T at low temperature. In order to investigate the spin structure in an ordered state by 19F-NMR, we have determined the anisotropic hyperfine coupling tensors for each three fluorine sites in the paramagnetic state. The measurement field was raised up to 10 T to achieve highest resolution. The preliminary analysis using the obtained hyperfine tensors has shown that the archetypal 120°-type structure in ab-plane does not accord with the NMR spectra of ordered state.
Ground-State Entanglement and Mixture in an XXZ Spin Chain
Institute of Scientific and Technical Information of China (English)
WANG Cheng-Zhi; LI Chun-Xian; GUO Guang-Can
2005-01-01
@@ We study the pairwise entanglement and mixture of a three-qubit XXZ spin chain in the ground state in thepresence of an external magnetic field B. The effects of the magnetic field, the anisotropy and the temperature on the entanglement and mixture are considered, and entanglement versus the mixture of all the two-spin states is investigated. We find that the maximal entangled mixed state can be obtained in the considered system by controlling the magnetic field. Our results provide another way to generate maximally entangled mixed states.
Ground-state phase diagram of the Kondo lattice model on triangular-to-kagome lattices
Akagi, Yutaka; Motome, Yukitoshi
2012-01-01
We investigate the ground-state phase diagram of the Kondo lattice model with classical localized spins on triangular-to-kagome lattices by using a variational calculation. We identify the parameter regions where a four-sublattice noncoplanar order is stable with a finite spin scalar chirality while changing the lattice structure from triangular to kagome continuously. Although the noncoplanar spin states appear in a wide range of parameters, the spin configurations on the kagome network beco...
Ground state of medium-heavy doubly-closed shell nuclei in correlated basis function theory
Bisconti, C; Có, G; Fabrocini, A
2006-01-01
The correlated basis function theory is applied to the study of medium-heavy doubly closed shell nuclei with different wave functions for protons and neutrons and in the jj coupling scheme. State dependent correlations including tensor correlations are used. Realistic two-body interactions of Argonne and Urbana type, together with three-body interactions have been used to calculate ground state energies and density distributions of the 12C, 16O, 40Ca, 48Ca and 208Pb nuclei.
Generalized Klein-Gordon models: Behavior around the ground state condensate
Kuetche, Victor K.
2014-07-01
In this work, we investigate the balance between the nonlinear and linear interaction energy of an interparticle anharmonic system in the vicinity of the ground state condensate. As a result, we find that the nonlinear interaction energy is very significant in the vicinity of each degree of freedom. We address some potential applications of the findings to miscellaneous areas of interests such as soliton theory, hydrodynamics, solid state physics, ferromagnetic and ferroelectric domain walls, condensed matter physics, and particle physics, among others.
Generalized Klein-Gordon models: behavior around the ground state condensate.
Kuetche, Victor K
2014-07-01
In this work, we investigate the balance between the nonlinear and linear interaction energy of an interparticle anharmonic system in the vicinity of the ground state condensate. As a result, we find that the nonlinear interaction energy is very significant in the vicinity of each degree of freedom. We address some potential applications of the findings to miscellaneous areas of interests such as soliton theory, hydrodynamics, solid state physics, ferromagnetic and ferroelectric domain walls, condensed matter physics, and particle physics, among others.
Evolution of the Hox gene complex from an evolutionary ground state.
Gehring, Walter J; Kloter, Urs; Suga, Hiroshi
2009-01-01
In this chapter, we consider the question of how the ordered clusters of Hox genes arose during evolution. Since ordered Hox clusters are found in all major superphyla, we have to assume that the Hox clusters arose before the Cambrian "explosion" giving rise to all of these taxa. Based on his studies of the bithorax complex (BX-C) in Drosophila Lewis considered the ground state to be the mesothoracic segment (T2) since the deletion of all of the genes of the BX-C leads to a transformation of all segments from T3 to A8/9 (the last abdominal segment) into T2 segments. We define the developmental ground state genetically, by assuming that loss-of-function mutants lead to transformations toward the ground state, whereas gain-of-function mutants lead to homeotic transformations away from the ground state. By this definition, T2 also represents the developmental ground state, if one includes the anterior genes, that is, those of the Antennapedia complex. We have reconstructed the evolution of the Hox cluster on the basis of known genetic mechanisms which involve unequal crossover and lead from an urhox gene, first to an anterior and a posterior gene and subsequently to intermediate genes which are progressively inserted, between the anterior and posterior genes. These intermediate genes are recombinant due to unequal crossover, whereas the anterior and posterior genes are not affected and therefore had the longest time to diverge from the urhox gene. The molecular phylogenetic analysis strongly supports this model. We consider the ground state to be both developmental and evolutionary and to represent the prototypic body segment. It corresponds to T2 and is specified by Antennapedia or Hox6, respectively. Experiments in the mouse also suggest that the ground state is a thoracic segment. Evolution leads from the prototypic segment to segmental divergence in both the anterior and posterior direction. The most anterior head and tail segments are specified by homeobox genes
Zeng, Zebing
2012-09-05
Stable open-shell polycyclic aromatic hydrocarbons (PAHs) are of fundamental interest due to their unique electronic, optical, and magnetic properties and promising applications in materials sciences. Chichibabin\\'s hydrocarbon as a classical open-shell PAH has been investigated for a long time. However, most of the studies are complicated by their inherent high reactivity. In this work, two new stable benzannulated Chichibabin\\'s hydrocarbons 1-CS and 2-OS were prepared, and their electronic structure and geometry in the ground state were studied by various experiments (steady-state and transient absorption spectra, NMR, electron spin resonance (ESR), superconducting quantum interference device (SQUID), FT Raman, X-ray crystallographic etc.) and density function theory (DFT) calculations. 1-CS and 2-OS exhibited tunable ground states, with a closed-shell quinoidal structure for 1-CS and an open-shell biradical form for 2-OS. Their corresponding excited-state forms 1-OS and 2-CS were also chemically approached and showed different decay processes. The biradical 1-OS displayed an unusually slow decay to the ground state (1-CS) due to a large energy barrier (95 ± 2.5 kJ/mol) arising from severe steric hindrance during the transition from an orthogonal biradical form to a butterfly-like quinoidal form. The quick transition from the quinoidal 2-CS (excited state) to the orthogonal biradicaloid 2-OS (ground state) happened during the attempted synthesis of 2-CS. Compounds 1-CS and 2-OS can be oxidized into stable dications by FeCl 3 and/or concentrated H 2SO 4. The open-shell 2-OS also exhibited a large two-photon absorption (TPA) cross section (760 GM at 1200 nm). © 2012 American Chemical Society.
The dispersed fluorescence spectrum of NaAr - Ground and excited state potential curves
Tellinghuisen, J.; Ragone, A.; Kim, M. S.; Auerbach, D. J.; Smalley, R. E.; Wharton, L.; Levy, D. H.
1979-01-01
Potential curves for the ground state and the first excited state of NaAr were determined. The van der Waals molecule NaAr was prepared by supersonic free jet expansion of a mixture of sodium, argon, and helium. The electronic transition from the ground state to the first excited state A2pi was excited by a tunable dye laser and the resulting fluorescence was studied. The dispersed fluorescence spectra show discrete and diffuse features, corresponding to transitions from excited vibrational levels of the A state to bound and unbound levels of the x state. The characteristic reflection structure in the bound-free spectra permits an unambiguous assignment of the vibrational numbering in the A state, and this assignment together with previously measured spectroscopic constants are used to calculate the potential curve of the A state. The discrete structure in the fluorescence spectra is used to determine the potential curve of the x state in the well region, and the repulsive part of the X curve is then deduced through trial-and-error simulation of the bound-free spectra.
Rajak, A.; Chakrabarti, B. K.
2014-09-01
Here we first discuss briefly the quantum annealing technique. We then study the quantum annealing of Sherrington-Kirkpatrick spin glass model with the tuning of both transverse and longitudinal fields. Both the fields are time-dependent and vanish adiabatically at the same time, starting from high values. We solve, for rather small systems, the time-dependent Schrodinger equation of the total Hamiltonian by employing a numerical technique. At the end of annealing we obtain the final state having high overlap with the exact ground state(s) of classical spin glass system (obtained independently).
Ground-state kinetics of bistable redox-active donor-acceptor mechanically interlocked molecules.
Fahrenbach, Albert C; Bruns, Carson J; Li, Hao; Trabolsi, Ali; Coskun, Ali; Stoddart, J Fraser
2014-02-18
The ability to design and confer control over the kinetics of theprocesses involved in the mechanisms of artificial molecular machines is at the heart of the challenge to create ones that can carry out useful work on their environment, just as Nature is wont to do. As one of the more promising forerunners of prototypical artificial molecular machines, chemists have developed bistable redox-active donor-acceptor mechanically interlocked molecules (MIMs) over the past couple of decades. These bistable MIMs generally come in the form of [2]rotaxanes, molecular compounds that constitute a ring mechanically interlocked around a dumbbell-shaped component, or [2]catenanes, which are composed of two mechanically interlocked rings. As a result of their interlocked nature, bistable MIMs possess the inherent propensity to express controllable intramolecular, large-amplitude, and reversible motions in response to redox stimuli. In this Account, we rationalize the kinetic behavior in the ground state for a large assortment of these types of bistable MIMs, including both rotaxanes and catenanes. These structures have proven useful in a variety of applications ranging from drug delivery to molecular electronic devices. These bistable donor-acceptor MIMs can switch between two different isomeric states. The favored isomer, known as the ground-state co-conformation (GSCC) is in equilibrium with the less favored metastable state co-conformation (MSCC). The forward (kf) and backward (kb) rate constants associated with this ground-state equilibrium are intimately connected to each other through the ground-state distribution constant, KGS. Knowing the rate constants that govern the kinetics and bring about the equilibration between the MSCC and GSCC, allows researchers to understand the operation of these bistable MIMs in a device setting and apply them toward the construction of artificial molecular machines. The three biggest influences on the ground-state rate constants arise from
Radon concentrations in ground and drinking water in the state of Chihuahua, Mexico.
Villalba, L; Colmenero Sujo, L; Montero Cabrera, M E; Cano Jiménez, A; Rentería Villalobos, M; Delgado Mendoza, C J; Jurado Tenorio, L A; Dávila Rangel, I; Herrera Peraza, E F
2005-01-01
This paper reports (222)Rn concentrations in ground and drinking water of nine cities of Chihuahua State, Mexico. Fifty percent of the 114 sampled wells exhibited (222)Rn concentrations exceeding 11Bq/L, the maximum contaminant level (MCL) recommended by the USEPA. Furthermore, around 48% (123 samples) of the tap-water samples taken from 255 dwellings showed radon concentrations over the MCL. There is an apparent correlation between total dissolved solids and radon concentration in ground-water. The high levels of (222)Rn found may be entirely attributed to the nature of aquifer rocks.
Self-Similar Collapse Solutions for Cylindrical Cloud Geometries and Dynamic Equations of State
Holden, Lisa; Baxter, Benjamin; Fatuzzo, Marco
2009-01-01
A self-similar formalism for the study of the gravitational collapse of molecular gas provides an important theoretical framework from which to explore the dynamics of star formation. Motivated by the presence of elongated and filamentary structures observed in giant molecular clouds, we build upon the existing body of work on cylindrical self-similar collapse flows by including dynamic equations of state that are different from the effective equation of state that produces the initial density distribution. We focus primarily on the collapse of initial states for which the gas is at rest and everywhere overdense from its corresponding hydrostatic equilibrium profile by a factor $\\Lambda$, and apply our results toward the analysis of star formation within dense, elongated molecular cores. An important aspect of this work is the determination of the mass infall rates over a range of the parameters which define the overall state of the gas -- the overdensity parameter $\\Lambda$, the index $\\Gamma$ of the static ...
Determining Transition State Geometries in Liquids Using 2D-IR
Energy Technology Data Exchange (ETDEWEB)
Harris, Charles; Cahoon, James F.; Sawyer, Karma R.; Schlegel, Jacob P.; Harris, Charles B.
2007-12-11
Many properties of chemical reactions are determined by the transition state connecting reactant and product, yet it is difficult to directly obtain any information about these short-lived structures in liquids. We show that two-dimensional infrared (2D-IR) spectroscopy can provide direct information about transition states by tracking the transformation of vibrational modes as a molecule crossed a transition state. We successfully monitored a simple chemical reaction, the fluxional rearrangement of Fe(CO)5, in which the exchange of axial and equatorial CO ligands causes an exchange of vibrational energy between the normal modes of the molecule. This energy transfer provides direct evidence regarding the time scale, transition state, and mechanism of the reaction.
Ground-state properties of K-isotopes from laser and $\\beta$-NMR spectroscopy
Lievens, P; Rajabali, M M; Krieger, A R
By combining high-resolution laser spectroscopy with $\\beta$-NMR spectroscopy on polarized K-beams we aim to establish the ground-state spins and magnetic moments of the neutron-rich $^{48,49,50,51}$K isotopes from N=29 to N=32. Spins and magnetic moments of the odd-K isotopes up to N=28 reveal an inversion of the ground-state, from the normal $\\,{I}$=3/2 ($\\pi{d}_{3/2}^{-1}$) in $^{41-45}$K$\\to\\,{I}$=1/2 ($\\pi{s}_{1/2}^{-1}$) in $^{47}$K. This inversion of the proton single particle levels is related to the strong proton $d_{3/2}$ - neutron $f_{7/2}$ interaction which lowers the energy of the $\\pi{d}_{3/2}$ single particle state when filling the $\
Study of polonium isotopes ground state properties by simultaneous atomic- and nuclear-spectroscopy
Koester, U H; Kalaninova, Z; Imai, N
2007-01-01
We propose to systematically study the ground state properties of neutron deficient $^{192-200}$Po isotopes by means of in-source laser spectroscopy using the ISOLDE laser ion source coupled with nuclear spectroscopy at the detection setup as successfully done before by this collaboration with neutron deficient lead isotopes. The study of the change in mean square charge radii along the polonium isotope chain will give an insight into shape coexistence above the mid-shell N = 104 and above the closed shell Z = 82. The hyperfine structure of the odd isotopes will also allow determination of the nuclear spin and the magnetic moment of the ground state and of any identifiable isomer state. For this study, a standard UC$_{x}$ target with the ISOLDE RILIS is required for 38 shifts.
Three-dimensional quantum calculations on the ground and excited state vibrations of ethylene
Groenenboom, Gerrit Cornelis
Three dimensional potential energy surfaces of the ground and excited states of ethylene were calculated at the MRCEPA (Multi Reference Coupled Electronic Pair Approximation) level. The modes included are the torsion, the CC stretch, and the symmetric scissors. Full vibrational calculations were performed using the Lanczos/grid method. The avoided crossing between the V and the R state was dealt with in a diabetic model. The ground state results agree within 3 up to the highest vibrational level known experimentally. The origin and the maximum of the V back arrow N band are calculated at 5.68 and 7.82 eV, respectively, approximately 0.2 eV above the somewhat ambiguous experimental values. This work considerably diminishes the existing gap of approximately 0.5 eV between theory and experiment.
Ground states of bilayered and extended t-J-U models
Energy Technology Data Exchange (ETDEWEB)
Voo, Khee-Kyun, E-mail: kkvoo@mail.oit.edu.tw
2015-09-04
The ground states of bilayered and extended t-J-U models are investigated with renormalized mean field theory. The trial wave functions are Gutzwiller projected Hartree–Fock states, and the site double occupancies are variational parameters. It is found that a spontaneous interlayer phase separation (PS) may arise in bilayers. In electron–hole doping asymmetric systems, the propensity for PS is stronger in electron doped bands. Via a PS, superconductivity can survive to lower doping densities, and antiferromagnetism in electron doped systems may survive to higher doping densities. The result is related to the superconducting cuprates. - Highlights: • Ground states in doped bilayered t-J-U models are studied. • Variational wave functions are Gutzwiller projected wave functions. • Site double occupancies are variational parameters. • Spontaneous interlayer phase separation may occur in bilayers. • Stronger tendency toward phase separation in electron doped bilayers.
Ground-State Cooling of a Mechanical Oscillator by Interference in Andreev Reflection
Stadler, P.; Belzig, W.; Rastelli, G.
2016-11-01
We study the ground-state cooling of a mechanical oscillator linearly coupled to the charge of a quantum dot inserted between a normal metal and a superconducting contact. Such a system can be realized, e.g., by a suspended carbon nanotube quantum dot with a capacitive coupling to a gate contact. Focusing on the subgap transport regime, we analyze the inelastic Andreev reflections which drive the resonator to a nonequilibrium state. For small coupling, we obtain that vibration-assisted reflections can occur through two distinct interference paths. The interference determines the ratio between the rates of absorption and emission of vibrational energy quanta. We show that ground-state cooling of the mechanical oscillator can be achieved for many of the oscillator's modes simultaneously or for single modes selectively, depending on the experimentally tunable coupling to the superconductor.
Vacuum polarization in the ground states of bi-muonic helium atoms
Energy Technology Data Exchange (ETDEWEB)
Frolov, Alexei M [Department of Chemistry, Queen' s University, Kingston, ON K7L 3N6 (Canada)
2004-11-28
The energies and bound-state properties of the bi-muonic helium-3 and helium-4 atoms in their ground 1{sup 1}(S = 0)-states are determined to very high accuracy. It is shown that the lowest order QED (and relativistic) effects play a significantly larger role in the case of bi-muonic {sup 3}He{mu}{sub 2} and {sup 4}He{mu}{sub 2} atoms than in the two-electron He-atoms. In particular, the effect of vacuum polarization and corresponding energy shifts for the ground 1{sup 1}(S 0)-states in the bi-muonic helium-3 and helium-4 atoms have been evaluated.
Aaron, Jean-Jacques; Diabou Gaye, Mame; Párkányi, Cyril; Cho, Nam Sook; Von Szentpály, László
1987-01-01
The ground-state dipole moments of seven biologically important purines (purine, 6-chloropurine, 6-mercaptopurine, hypoxanthine, theobromine, theophylline and caffeine) were determined at 25°C in acetic acid (all the above compounds with the exception of purine) and in ethyl acetate (purine, theophylline and caffeine). Because of its low solubility, it was not possible to measure the dipole moment of uric acid. The first excited singlet-state dipole moments were obtained on the basis of the Bakhshiev and Chamma—Viallet equations using the variation of the Stokes shift with the solvent dielectric constant-refractive index term. The theoretical dipole moments for all the purines listed above and including uric acid were calculated by combining the use of the PPP (π-LCI-SCF-MO) method for the π-contribution to the overall dipole moment with the σ-contribution obtained as a vector sum of the σbond moments and group moments. The experimental and theoretical values were compared with the data available in the literature for some of the purines under study. For several purines, the calculations were carried out for different tautomeric forms. Excited singlet-state dipole moments are smaller than the ground-state values by 0.8 to 2.2 Debye units for all purines under study with the exception of 6-chloropurine. The effects of the structure upon the ground- and excited-state dipole moments of the purines are discussed.
Spectroscopy of ground and excited states of pseudoscalar and vector charmonium and bottomonium
Negash, Hluf; Bhatnagar, Shashank
2016-07-01
In this paper, we calculate the mass spectrum, weak decay constants, two photon decay widths, and two-gluon decay widths of ground (1S) and radially excited (2S, 3S,…) states of pseudoscalar charmoniuum and bottomonium such as ηc and ηb, as well as the mass spectrum and leptonic decay constants of ground state (1S), excited (2S, 1D, 3S, 2D, 4S,…, 5D) states of vector charmonium and bottomonium such as J/ψ, and Υ, using the formulation of Bethe-Salpeter equation under covariant instantaneous ansatz (CIA). Our results are in good agreement with data (where ever available) and other models. In this framework, from the beginning, we employ a 4 × 4 representation for two-body (qq¯) BS amplitude for calculating both the mass spectra as well as the transition amplitudes. However, the price we have to pay is to solve a coupled set of equations for both pseudoscalar and vector quarkonia, which we have explicitly shown get decoupled in the heavy-quark approximation, leading to mass spectral equation with analytical solutions for both masses, as well as eigenfunctions for all the above states, in an approximate harmonic oscillator basis. The analytical forms of eigenfunctions for ground and excited states so obtained are used to evaluate the decay constants and decay widths for different processes.
Vexiau, R; Aymar, M; Bouloufa-Maafa, N; Dulieu, O
2015-01-01
We have calculated the isotropic $C\\_6$ coefficients characterizing the long-range van der Waals interaction between two identical heteronuclear alkali-metal diatomic molecules in the same arbitrary vibrational level of their ground electronic state $X^1\\Sigma^+$. We consider the ten species made up of $^7$Li, $^{23}$Na, $^{39}$K, $^{87}$Rb and $^{133}$Cs. Following our previous work [M.~Lepers \\textit{et.~al.}, Phys.~Rev.~A \\textbf{88}, 032709 (2013)] we use the sum-over-state formula inherent to the second-order perturbation theory, composed of the contributions from the transitions within the ground state levels, from the transition between ground-state and excited state levels, and from a crossed term. These calculations involve a combination of experimental and quantum-chemical data for potential energy curves and transition dipole moments. We also investigate the case where the two molecules are in different vibrational levels and we show that the Moelwyn-Hughes approximation is valid provided that it i...
Ground and Low-Lying Collective States of Rotating Three-Boson System
Imran, Mohd.; Ahsan, M. A. H.
2016-04-01
The ground and low-lying collective states of a rotating system of N = 3 bosons harmonically confined in quasi-two-dimension and interacting via repulsive finite-range Gaussian potential is studied in weakly to moderately interacting regime. The N-body Hamiltonian matrix is diagonalized in subspaces of quantized total angular momenta 0 ≥ L ≥ 4N to obtain the ground and low-lying eigenstates. Our numerical results show that breathing modes with N-body eigenenergy spacing of 2ħω⊥, known to exist in strictly 2D system with zero-range (δ-function) interaction potential, may as well exist in quasi-2D system with finite-range Gaussian interaction potential. To gain an insight into the many-body states, the von Neumann entropy is calculated as a measure of quantum correlation and the conditional probability distribution is analyzed for the internal structure of the eigenstates. In the rapidly rotating regime the ground state in angular momentum subspaces L = (q/2)N (N - 1) with q = 2, 4 is found to exhibit the anticorrelation structure suggesting that it may variationally be described by a Bose-Laughlin like state. We further observe that the first breathing mode exhibits features similar to the Bose-Laughlin state in having eigenenergy, von Neumann entropy and internal structure independent of interaction for the three-boson system considered here. On the contrary, for eigenstates lying between the Bose-Laughlin like ground state and the first breathing mode, values of eigenenergy, von Neumann entropy and internal structure are found to vary with interaction.
Long-range magnetic fields in the ground state of the Standard Model plasma
Boyarsky, Alexey; Shaposhnikov, Mikhail
2012-01-01
In thermal equilibrium the ground state of the plasma of Standard Model particles is determined by temperature and exactly conserved combinations of baryon and lepton numbers. We show that at non-zero values of the global charges a translation invariant and homogeneous state of the plasma becomes unstable and the system transits into a new state, containing a large-scale magnetic field. The origin of this effect is the parity-breaking character of weak interactions and chiral anomaly. This situation can occur in the early Universe and may play an important role in its subsequent evolution.
Long-Range Magnetic Fields in the Ground State of the Standard Model Plasma
Boyarsky, Alexey; Ruchayskiy, Oleg; Shaposhnikov, Mikhail
2012-09-01
In thermal equilibrium the ground state of the plasma of Standard Model particles is determined by temperature and exactly conserved combinations of baryon and lepton numbers. We show that at nonzero values of the global charges a translation invariant and homogeneous state of the plasma becomes unstable and the system transits into a new equilibrium state, containing a large-scale magnetic field. The origin of this effect is the parity-breaking character of weak interactions and chiral anomaly. This situation could occur in the early Universe and may play an important role in its subsequent evolution.
Ground state of an antiferromagnetic superconductor in the presence of a homogeneous magnetic field
Energy Technology Data Exchange (ETDEWEB)
Suzumura, Y.; Naji, A.D.S. (Waterloo Univ., Ontario (Canada). Dept. of Physics)
1981-11-01
The effect of a homogeneous magnetic field, H/sub 0/. on the ground state of an antiferromagnetic superconductor has been investigated. Assuming a one-dimensional like half-filled band, a new state has been found having gapless superconductivity and H/sub 0/-dependent order parameter. This state exists for Hsub(Q)/..delta../sub 0/ > 0.22 and when ..delta.. - Hsub(Q) <= H/sub 0/ < ..delta.. + Hsub(Q) Hsub(Q) is the staggered magnetic field, ..delta.. is the superconducting order parameter and ..delta../sub 0/ is ..delta.. in the absence of Hsub(Q) and H/sub 0/.
Extended Ho\\v{r}ava Gravity with Physical Ground-State Wavefunction
Shu, Fu-Wen
2010-01-01
We propose a new extended theory of Ho\\v{r}ava gravity based on the following three conditions: (i) UV completion, (ii) healthy IR behavior and (iii) a stable vacuum state in quantized version of the theory. Compared with other extended theories, we stress that any realistic theory of gravity must have physical ground states when quantization is performed. To fulfill the three conditions, we softly break the detailed balance but keep its basic structure unchanged. It turns out that the new model constructed in this way can avoid the strong coupling problem and remains power-counting renormalizable, moreover, it has a stable vacuum state by an appropriate choice of parameters.
Ground-state isolation and discrete flows in a rationally extended quantum harmonic oscillator
Cariñena, José F
2016-01-01
Ladder operators for the simplest version of a rationally extended quantum harmonic oscillator (REQHO) are constructed by applying a Darboux transformation to the quantum harmonic oscillator system. It is shown that the physical spectrum of the REQHO carries a direct sum of a trivial and an infinite-dimensional irreducible representation of the polynomially deformed bosonized osp(1|2) superalgebra. In correspondence with this the ground state of the system is isolated from other physical states but can be reached by ladder operators via non-physical energy eigenstates, which belong to either an infinite chain of similar eigenstates or to the chains with generalized Jordan states. We show that the discrete chains of the states generated by ladder operators and associated with physical energy levels include six basic generalized Jordan states, in comparison with the two basic Jordan states entering in analogous discrete chains for the quantum harmonic oscillator.
Influence of the Geometry of Beveled Edges on the Stress-Strain State of Hydraulic Cylinders
Buyalich, G. B.; Anuchin, A. V.; Serikov, K. P.
2016-04-01
The studies were carried out to determine the influence of forms obtained when preparing edges for welding a cylinder for hydraulic legs; the maximum stresses were defined at the location of weld roots, depending on variable parameters. The stress-strain states were calculated using finite element method.
Structural instability and ground state of the U{sub 2}Mo compound
Energy Technology Data Exchange (ETDEWEB)
Losada, E.L., E-mail: losada@cab.cnea.gov.ar [SIM" 3, Centro Atómico Bariloche, Comisión Nacional de Energía Atómica (Argentina); Garcés, J.E. [Gerencia de Investigación y Aplicaciones Nucleares, Comisión Nacional de Energía Atómica (Argentina)
2015-11-15
This work reports on the structural instability at T = 0 °K of the U{sub 2}Mo compound in the C11{sub b} structure under the distortion related to the C{sub 66} elastic constant. The electronic properties of U{sub 2}Mo such as density of states (DOS), bands and Fermi surface (FS) are studied to understand the source of the instability. The C11{sub b} structure can be interpreted as formed by parallel linear chains along the z-directions each one composed of successive U–Mo–U blocks. Hybridization due to electronic interactions inside the U–Mo–U blocks is slightly modified under the D{sub 6} distortion. The change in distance between chains modifies the U–U interaction and produces a split of f-states. The distorted structure is stabilized by a decrease in energy of the hybridized states, mainly between d-Mo and f-U states, together with the f-band split. Consequently, an induced Peierls distortion is produced in U{sub 2}Mo due to the D{sub 6} distortion. It is important to note that the results of this work indicate that the structure of the ground state of the U{sub 2}Mo compound is not the assumed C11{sub b} structure. It is suggested for the ground state a structure with hexagonal symmetry (P6 #168), ∼0.1 mRy below the energy of the recently proposed Pmmn structure. - Highlights: • Structural instability of the C11b compound due to the D6 deformation. • Induced Peierls distortion due to the D6 deformation. • Distorted structure is stabilized by hybridization and split of f-Uranium state. • P6 (#168) suggested ground state for the U{sub 2}Mo compound.
Kvaal, Simen; Helgaker, Trygve
2015-11-14
The relationship between the densities of ground-state wave functions (i.e., the minimizers of the Rayleigh-Ritz variation principle) and the ground-state densities in density-functional theory (i.e., the minimizers of the Hohenberg-Kohn variation principle) is studied within the framework of convex conjugation, in a generic setting covering molecular systems, solid-state systems, and more. Having introduced admissible density functionals as functionals that produce the exact ground-state energy for a given external potential by minimizing over densities in the Hohenberg-Kohn variation principle, necessary and sufficient conditions on such functionals are established to ensure that the Rayleigh-Ritz ground-state densities and the Hohenberg-Kohn ground-state densities are identical. We apply the results to molecular systems in the Born-Oppenheimer approximation. For any given potential v ∈ L(3/2)(ℝ(3)) + L(∞)(ℝ(3)), we establish a one-to-one correspondence between the mixed ground-state densities of the Rayleigh-Ritz variation principle and the mixed ground-state densities of the Hohenberg-Kohn variation principle when the Lieb density-matrix constrained-search universal density functional is taken as the admissible functional. A similar one-to-one correspondence is established between the pure ground-state densities of the Rayleigh-Ritz variation principle and the pure ground-state densities obtained using the Hohenberg-Kohn variation principle with the Levy-Lieb pure-state constrained-search functional. In other words, all physical ground-state densities (pure or mixed) are recovered with these functionals and no false densities (i.e., minimizing densities that are not physical) exist. The importance of topology (i.e., choice of Banach space of densities and potentials) is emphasized and illustrated. The relevance of these results for current-density-functional theory is examined.
Institute of Scientific and Technical Information of China (English)
XIE Bing-Hao; ZHANG Hong-Biao; CHEN Jing-Ling
2002-01-01
An algebraic diagonalization method is proposed. As two examples, the Hamiltonians of BCS ground stateunder mean-field approximation and XXZ antiferromagnetic model in linear spin-wave frame have been diagonalized byusing SU(2), SU(1,1) Lie algebraic method, respectively. Meanwhile, the eigenstates of the above two models are revealedto be SU(2), SU(1,1) coherent states, respectively. The relation between the usual Bogoliubov Valatin transformationand the algebraic method in a special case is also discussed.
Kumar, A.; Wagner, L. S.; Beck, S. L.; Young, B. E.; Zandt, G.; Long, M. D.; Tavera, H.; Minaya, E.
2013-12-01
Subduction of the Nazca plate in the north central Andes beneath southern Peru and northern Bolivia is of prime importance because of the role it plays in the evolution of topographic features since the late Eocene (~40 Ma). Previous studies based on slab event locations constrained only with teleseismic data defined a broad area of flat slab subduction in central and southern Peru, which transitions to a normally dipping slab beneath the northernmost Altiplano Plateau. We present earthquake locations and focal mechanisms using data from two temporary arrays: the network of 50 broadband seismic stations that were part of the NSF-Continental Dynamics-funded project 'CAUGHT' (Central Andean Uplift and the Geodynamics of High Topography) and the 40 station NSF- Geophysics funded 'PULSE' array (PerU Lithosphere and Slab Experiment). Our earthquake locations provide new information about the geometry of subducting Nazca slab between 13°S to 18°S. A significant clustering of intermediate depth earthquakes at ~15.5°S and 18°S suggests strong and localized release of tectonic stress in the slab perhaps due to bending and unbending. There are not enough intra-slab events at depth greater than 100 km to constrain the flat slab width north of 14°S. Our analyses indicate that the flat slab is at least 10 to 12 km shallower than the previous estimates (e.g. Cahill and Isacks, 1992; Ramos, 2009). Focal mechanisms and stress axis orientation of slab events at ~15.5°S indicate down-dip extension, where the dip changes from subhorizontal to steeply dipping slab. The continuity in the trend of stress suggests that the slab is deformed but not torn where it transitions from flat to steeply dipping. Data from local slab events will eventually be incorporated into a local tomographic body wave inversion to better constrain the velocity structure of the mantle lithosphere and asthenosphere below the Altiplano. This in turn will provide the valuable information on the process
Antiferromagnetic ground state with pair-checkerboard order in FeSe
Cao, Hai-Yuan; Chen, Shiyou; Xiang, Hongjun; Gong, Xin-Gao
2015-01-01
A monolayer FeSe thin film grown on SrTiO3(001) (STO) shows the sign of Tc>77 K , which is higher than the Tc record of 56 K for bulk FeAs-based superconductors. However, little is known about the magnetic ground state of FeSe, which should be closely related to its unusual superconductivity. Previous studies presume the collinear stripe antiferromagnetic (AFM) state as the ground state of FeSe, the same as that in FeAs superconductors. Here we find a magnetic order named the "pair-checkerboard AFM" as the magnetic ground state of tetragonal FeSe. The pair-checkerboard order results from the interplay between the nearest-, next-nearest, and unnegligible next-next-nearest neighbor magnetic exchange couplings of Fe atoms. The monolayer FeSe in pair-checkerboard order shows an unexpected insulating behavior with a Dirac-cone-like band structure related to the specific orbital order of the dx z and dy z characters of Fe atoms, which could explain the recently observed insulator-superconductor transition. The present results cast insights on the magnetic ordering in FeSe monolayer and its derived superconductors.
Routh, J A; Pringle, J; Mohr, M; Bidol, S; Arends, K; Adams-Cameron, M; Hancock, W T; Kissler, B; Rickert, R; Folster, J; Tolar, B; Bosch, S; Barton Behravesh, C; Williams, I T; Gieraltowski, L
2015-11-01
On 23 May 2011, CDC identified a multistate cluster of Salmonella Heidelberg infections and two multidrug-resistant (MDR) isolates from ground turkey retail samples with indistinguishable pulsed-field gel electrophoresis patterns. We defined cases as isolation of outbreak strains in persons with illness onset between 27 February 2011 and 10 November 2011. Investigators collected hypothesis-generating questionnaires and shopper-card information. Food samples from homes and retail outlets were collected and cultured. We identified 136 cases of S. Heidelberg infection in 34 states. Shopper-card information, leftover ground turkey from a patient's home containing the outbreak strain and identical antimicrobial resistance profiles of clinical and retail samples pointed to plant A as the source. On 3 August, plant A recalled 36 million pounds of ground turkey. This outbreak increased consumer interest in MDR Salmonella infections acquired through United States-produced poultry and played a vital role in strengthening food safety policies related to Salmonella and raw ground poultry.
Directory of Open Access Journals (Sweden)
Baiyu Liu
2014-01-01
Full Text Available We consider a class of coupled nonlinear Schrödinger systems with potential terms and combined power-type nonlinearities. We establish the existence of ground states, by using a variational method. As an application, some symmetry results for ground states of Schrödinger systems with harmonic potential terms are obtained.
Institute of Scientific and Technical Information of China (English)
姜伟; 魏国柱; 杜安; 张起
2002-01-01
The properties of the ground state in the spin-2 transverse Ising model with the presence of a crystal field arestudied by using the effective-field theory with correlations. The longitudinal and transverse magnetizations, the phasediagram and the internal energy in the ground state are given numerically for a honeycomb lattice (z=3).
Institute of Scientific and Technical Information of China (English)
姜伟; 魏国柱; 等
2002-01-01
The properties of the ground state in the spin-2 transverse Ising model with the presence of a crystal of a crystal field are studied by using the effective-field theory with correlations,The longitudinal and transverse magnetizations,the phase diagram and the internal energy in the ground state are given numerically for a honeycomb lattice(z=3).
Competing ground states of strongly correlated bosons in the Harper-Hofstadter-Mott model
Natu, Stefan S.; Mueller, Erich J.; Das Sarma, S.
2016-06-01
Using an efficient cluster approach, we study the physics of two-dimensional lattice bosons in a strong magnetic field in the regime where the tunneling is much weaker than the on-site interaction strength. We study both the dilute, hard-core bosons at filling factors much smaller than unity occupation per site and the physics in the vicinity of the superfluid-Mott lobes as the density is tuned away from unity. For hard-core bosons, we carry out extensive numerics for a fixed flux per plaquette ϕ =1 /5 and ϕ =1 /3 . At large flux, the lowest-energy state is a strongly correlated superfluid, analogous to He-4, in which the order parameter is dramatically suppressed, but nonzero. At filling factors ν =1 /2 ,1 , we find competing incompressible states which are metastable. These appear to be commensurate density wave states. For small flux, the situation is reversed and the ground state at ν =1 /2 is an incompressible density wave solid. Here, we find a metastable lattice supersolid phase, where superfluidity and density wave order coexist. We then perform careful numerical studies of the physics near the vicinity of the Mott lobes for ϕ =1 /2 and ϕ =1 /4 . At ϕ =1 /2 , the superfluid ground state has commensurate density wave order. At ϕ =1 /4 , incompressible phases appear outside the Mott lobes at densities n =1.125 and n =1.25 , corresponding to filling fractions ν =1 /2 and 1, respectively. These phases, which are absent in single-site mean-field theory, are metastable and have slightly higher energy than the superfluid, but the energy difference between them shrinks rapidly with increasing cluster size, suggestive of an incompressible ground state. We thus explore the interplay between Mott physics, magnetic Landau levels, and superfluidity, finding a rich phase diagram of competing compressible and incompressible states.
Ground Water Atlas of the United States: Segment 1, California, Nevada
Planert, Michael; Williams, John S.
1995-01-01
California and Nevada compose Segment 1 of the Ground Water Atlas of the United States. Segment 1 is a region of pronounced physiographic and climatic contrasts. From the Cascade Mountains and the Sierra Nevada of northern California, where precipitation is abundant, to the Great Basin in Nevada and the deserts of southern California, which have the most arid environments in the United States, few regions exhibit such a diversity of topography or environment. Since the discovery of gold in the mid-1800's, California has experienced a population, industrial, and agricultural boom unrivaled by that of any other State. Water needs in California are very large, and the State leads the United States in agricultural and municipal water use. The demand for water exceeds the natural water supply in many agricultural and nearly all urban areas. As a result, water is impounded by reservoirs in areas of surplus and transported to areas of scarcity by an extensive network of aqueducts. Unlike California, which has a relative abundance of water, development in Nevada has been limited by a scarcity of recoverable freshwater. The Truckee, the Carson, the Walker, the Humboldt, and the Colorado Rivers are the only perennial streams of significance in the State. The individual basin-fill aquifers, which together compose the largest known ground-water reserves, receive little annual recharge and are easily depleted. Nevada is sparsely populated, except for the Las Vegas, the Reno-Sparks, and the Carson City areas, which rely heavily on imported water for public supplies. Although important to the economy of Nevada, agriculture has not been developed to the same degree as in California due, in large part, to a scarcity of water. Some additional ground-water development might be possible in Nevada through prudent management of the basin-fill aquifers and increased utilization of ground water in the little-developed carbonate-rock aquifers that underlie the eastern one-half of the State
Construction of the ground state in nonrelativistic QED by continuous flows
Bach, Volker; Könenberg, Martin
For a nonrelativistic hydrogen atom minimally coupled to the quantized radiation field we construct the ground state projection P by a continuous approximation scheme as an alternative to the iteration scheme recently used by Fröhlich, Pizzo, and the first author [V. Bach, J. Fröhlich, A. Pizzo, Infrared-finite algorithms in QED: The groundstate of an atom interacting with the quantized radiation field, Comm. Math. Phys. (2006), doi: 10.1007/s00220-005-1478-3]. That is, we construct P=limP as the limit of a continuously differentiable family ()t⩾0 of ground state projections of infrared regularized Hamiltonians H. Using the ODE solved by this family of projections, we show that the norm ‖P‖ of their derivative is integrable in t which in turn yields the convergence of P by the fundamental theorem of calculus.
Ground State Properties of New Element Z = 113 and Its Alpha Decay Chain
Institute of Scientific and Technical Information of China (English)
TAI Fei; CHEN Ding-Han; XU Chang; REN Zhong-Zhou
2005-01-01
@@ We investigate the ground state properties of the new element 278113 and of the α-decay chain with different models, where the new element Z = 113 has been produced at RIKEN in Japan by cold-fusion reaction [Morita et al.J.Phys.Soc.Jpn.73 (2004) 2593].The experimental decay energies are reproduced by the deformed relativistic mean-field model, by the Skyrme-Hartree-Fock (SHF) model, and by the macroscopic-microscopic model.Theoretical half-lives also reasonably agree with the data.Calculations further show that prolate deformation is important for the ground states of the nuclei in the α-decay chain of 278113.The common points and differences among different models are compared and discussed.
Electromagnetically-induced-transparency ground-state cooling of long ion strings
Lechner, Regina; Maier, Christine; Hempel, Cornelius; Jurcevic, Petar; Lanyon, Ben P.; Monz, Thomas; Brownnutt, Michael; Blatt, Rainer; Roos, Christian F.
2016-05-01
Electromagnetically-induced-transparency (EIT) cooling is a ground-state cooling technique for trapped particles. EIT offers a broader cooling range in frequency space compared to more established methods. In this work, we experimentally investigate EIT cooling in strings of trapped atomic ions. In strings of up to 18 ions, we demonstrate simultaneous ground-state cooling of all radial modes in under 1 ms. This is a particularly important capability in view of emerging quantum simulation experiments with large numbers of trapped ions. Our analysis of the EIT cooling dynamics is based on a technique enabling single-shot measurements of phonon numbers, by rapid adiabatic passage on a vibrational sideband of a narrow transition.
Energy of ground state in B-B'-U-Hubbard model in approximation of static fluctuations
Mironov, G I
2002-01-01
To explain some features of CuO sub 2 base high-temperature superconductors (HTSC) one should take account of possibility of electron transfer to the crystalline structure mode next to the nearest one. It terms of approximation of static fluctuations one calculated the energy of ground state in two-dimensional B-B'-U Hubbard model. Lattice is assumed to consist of two sublattices formed by various type atoms. The calculation results of ground state energy are compared with the precise solution for one-dimensional Hubbard model derived previously. Comparison of the precise and the approximated solutions shows that approximation of static fluctuations describes adequately behavior of the Hubbard studied model within both weak and strong correlation ranges
Influence of free carriers on exciton ground states in quantum wells
Energy Technology Data Exchange (ETDEWEB)
Klochikhin, A.A. [Ioffe Physical Technical Institute, 194021 St. Petersburg (Russian Federation); Nuclear Physics Institute, 350000 St. Petersburg (Russian Federation); Kochereshko, V.P., E-mail: vladimir.kochereshko@mail.ioffe.ru [Ioffe Physical Technical Institute, 194021 St. Petersburg (Russian Federation); Spin Optics Laboratory, St. Petersburg State University, 198904 St. Petersburg (Russian Federation); Tatarenko, S. [CEA-CNRS Group “Nanophysique et Semiconducteurs”, Institut Néel, CNRS and Universite Joseph Fourier, 25 Avenue des Martyrs, 38042 Grenoble (France)
2014-10-15
The influence of free carriers on the ground state of the exciton at zero magnetic field in a quasi-two-dimensional quantum well that contains a gas of free electrons is considered in the framework of the random phase approximation. The effects of the exciton–charge-density interaction and the inelastic scattering processes due to the electron–electron exchange interaction are taken into account. The effect of phase-space filling is considered using an approximate approach. The results of the calculation are compared with the experimental data. - Highlights: • We discussed the effect of free carriers on the exciton ground state in quantum wells. • The processes of exciton–electron scattering become the most important for excitons in doped QWs. • The direct Coulomb scattering can be neglected. • The most important becomes the exchange inelastic exciton–electron scattering.
VARIATIONAL CALCULATION ON GROUND-STATE ENERGY OF BOUND POLARONS IN PARABOLIC QUANTUM WIRES
Institute of Scientific and Technical Information of China (English)
WANG ZHUANG-BING; WU FU-LI; CHEN QING-HU; JIAO ZHENG-KUAN
2001-01-01
Within the framework of Feynman path-integral variational theory, we calculate the ground-state energy of a polaron in parabolic quantum wires in the presence of a Coulomb potential. It is shown that the polaronic correction to the ground-state energy is more sensitive to the electron-phonon coupling constant than the Coulomb binding parameter,and it increases monotonically with decreasing effective wire radius. Moreover, compared to the results obtained by Feynman Haken variational path-integral theory, we obtain better results within the Feynman path-integral variational approach (FV approach). Applying our calculation to several polar semiconductor quantum wires, we find that the polaronic correction can be considerably large.
Ultracold Dipolar Gas of Fermionic 23Na40 K Molecules in Their Absolute Ground State.
Park, Jee Woo; Will, Sebastian A; Zwierlein, Martin W
2015-05-22
We report on the creation of an ultracold dipolar gas of fermionic 23Na40 K molecules in their absolute rovibrational and hyperfine ground state. Starting from weakly bound Feshbach molecules, we demonstrate hyperfine resolved two-photon transfer into the singlet X 1Σ+|v=0,J=0⟩ ground state, coherently bridging a binding energy difference of 0.65 eV via stimulated rapid adiabatic passage. The spin-polarized, nearly quantum degenerate molecular gas displays a lifetime longer than 2.5 s, highlighting NaK's stability against two-body chemical reactions. A homogeneous electric field is applied to induce a dipole moment of up to 0.8 D. With these advances, the exploration of many-body physics with strongly dipolar Fermi gases of 23Na40K molecules is within experimental reach.
Relativistic analysis of nuclear ground state densities at 135 to 200 MeV
Indian Academy of Sciences (India)
M A Suhail; N Neeloffer; Z A Khan
2005-12-01
A relativistic analysis of p + 40Ca elastic scattering with different nuclear ground state target densities at 135 to 200 MeV is presented in this paper. It is found that the IGO densities are more consistent in reproducing the data over the energy range considered here. The reproduction of spin-rotation-function data with the simultaneous fitting of differential cross-section and analyzing power, and the appearance of wine-bottle-bottom shaped Re eff() in the transition energy region, sensitively depends on the input nuclear ground state densities and are not solely the relativistic characteristic signatures. We also found that the wine-bottle-bottom shaped Re eff() is preferred by the spin observables in the transition energy region (i.e. 181 MeV to 200 MeV).
Search for $^{12}$C+$^{12}$C clustering in $^{24}$Mg ground state
Indian Academy of Sciences (India)
B N JOSHI; ARUN K JAIN; D C BISWAS; B V JOHN; Y K GUPTA; L S DANU; R P VIND; G K PRAJAPATI; S MUKHOPADHYAY; A SAXENA
2017-02-01
In the backdrop of many models, the heavy cluster structure of the ground state of $^{24}$Mg has been probed experimentally for the first time using the heavy cluster knockout reaction $^{24}$Mg($^{12}$C, $^{212}$C)$^{12}$C in thequasifree scattering kinematic domain. In the ($^{12}$C, $^{212}$C) reaction, the direct $^{12}$C-knockout cross-section was found to be very small. Finite-range knockout theory predictions were much larger for ($^{12}$C, 212C) reaction,indicating a very small $^{12}$C−$^{12}$C clustering in $^{24}$Mg(g.s.). Our present results contradict most of the proposed heavy cluster ($^{12}$C+$^{12}$C) structure models for the ground state of $^{24}$Mg.
Adiabatic mixed-field orientation of ground-state-selected carbonyl sulfide molecules
Kienitz, Jens S; Mullins, Terry; Długołęcki, Karol; González-Férez, Rosario; Küpper, Jochen
2016-01-01
We experimentally demonstrated strong adiabatic mixed-field orientation of carbonyl sulfide molecules (OCS) in their absolute ground state of $\\text{N}_{\\text{up}}/\\text{N}_{\\text{tot}}=0.882$. OCS was oriented in combined non-resonant laser and static electric fields inside a two-plate velocity map imaging spectrometer. The transition from non-adiabatic to adiabatic orientation for the rotational ground state was studied by varying the applied laser and static electric field. Above static electric field strengths of 10~kV/cm and laser intensities of $10^{11} \\text{W/cm}^2$ the observed degree of orientation reached a plateau. These results are in good agreement with computational solutions of the time-dependent Schr\\"odinger equation.
Prospects for the formation of ultracold polar ground state KCs molecules via an optical process
Borsalino, D; Aymar, M; Luc-Koenig, E; Dulieu, O; Bouloufa-Maafa, N
2015-01-01
Heteronuclear alkali-metal dimers represent the class of molecules of choice for creating samples of ultracold molecules exhibiting an intrinsic large permanent electric dipole moment. Among them, the KCs molecule, with a permanent dipole moment of 1.92 Debye still remains to be observed in ultracold conditions. Based on spectroscopic studies available in the literature completed by accurate ab initio calculations, we propose several optical coherent schemes to create ultracold bosonic and fermionic KCs molecules in their absolute rovibrational ground level, starting from a weakly bound level of their electronic ground state manifold. The processes rely on the existence of convenient electronically excited states allowing an efficient stimulated Raman adiabatic transfer of the level population.
Study of ground and excited state decays in N ≈ Z Ag nuclei
Directory of Open Access Journals (Sweden)
Moschner K.
2015-01-01
Full Text Available A decay spectroscopy experiment was performed within the EURICA campaign at RIKEN in 2012. It aimed at the isomer and particle spectroscopy of excited states and ground states in the mass region below the doubly magic 100Sn. The N = Z nuclei 98In, 96Cd and 94Ag were of particular interest for the present study. Preliminary results on the neutron deficient nuclei 93Ag and 94Ag are presented. In 94Ag a more precise value for the half-life of the ground state’s superallowed Fermi transition was deduced. In addition the energy spectra of the mentioned decay could be reproduced through precise Geant4 simulations of the used active stopper SIMBA. This will enable us to extract Qβ values from the measured data. The decay of 93Ag is discussed based on the observed implantation-decay correlation events.
Candidates for Long Lived High-K Ground States in Superheavy Nuclei
Jachimowicz, P; Skalski, J
2015-01-01
On the basis of systematic calculations for 1364 heavy and superheavy nuclei, including odd-systems, we have found a few candidates for high-K ground states in superheavy nuclei. The macroscopic-microscopic model based on the deformed Woods-Saxon single particle potential which we use offers a reasonable description of SH systems, including known: nuclear masses, $Q_{\\alpha}$-values, fission barriers, ground state deformations, super- and hyper-deformed minima in the heaviest nuclei. %For odd and odd-odd systems, both ways of including pairing correlations, % blocking and the quasi-particle method, have been applied. Exceptionally untypical high-K intruder contents of the g.s. found for some nuclei accompanied by a sizable excitation of the parent configuration in daughter suggest a dramatic hindrance of the $\\alpha$-decay. Multidimensional hyper-cube configuration - constrained calculations of the Potential Energy Surfaces (PES's) for one especially promising candidate, $^{272}$ Mt, shows a $\\backsimeq$ 6 Me...
Ground state energy of a non-integer number of particles with δ attractive interactions
Brunet, Éric; Derrida, Bernard
2000-04-01
We show how to define and calculate the ground state energy of a system of quantum particles with δ attractive interactions when the number of particles n is non-integer. The question is relevant to obtain the probability distribution of the free energy of a directed polymer in a random medium. When one expands the ground state energy in powers of the interaction, all the coefficients of the perturbation series are polynomials in n, allowing to define the perturbation theory for non-integer n. We develop a procedure to calculate all the cumulants of the free energy of the directed polymer and we give explicit, although complicated, expressions of the first three cumulants.
Ground state correlations and mean-field in $^{16}O$, 2
Mihaila, B; Mihaila, Bogdan; Heisenberg, Jochen H.
2000-01-01
We continue the investigations of the $^{16}$O ground state using the coupled-cluster expansion [$\\exp({\\bf S})$] method with realistic nuclear interaction. In this stage of the project, we take into account the three nucleon interaction, and examine in some detail the definition of the internal Hamiltonian, thus trying to correct for the center-of-mass motion. We show that this may result in a better separation of the internal and center-of-mass degrees of freedom in the many-body nuclear wave function. The resulting ground state wave function is used to calculate the "theoretical" charge form factor and charge density. Using the "theoretical" charge density, we generate the charge form factor in the DWBA picture, which is then compared with the available experimental data. The longitudinal response function in inclusive electron scattering for $^{16}$O is also computed.
Towards the measurement of the ground-state hyperfine splitting of antihydrogen
Energy Technology Data Exchange (ETDEWEB)
Juhasz, Bertalan, E-mail: bertalan.juhasz@oeaw.ac.at [Austrian Academy of Sciences, Stefan Meyer Institute for Subatomic Physics (Austria)
2012-12-15
The ASACUSA collaboration at the Antiproton Decelerator of CERN is planning to measure the ground-state hyperfine splitting of antihydrogen using an atomic beam line, which will consist of a superconducting cusp trap as a source of partially polarized antihydrogen atoms, a radiofrequency spin-flip cavity, a superconducting sextupole magnet as spin analyser, and an antihydrogen detector. This will be a measurement of the antiproton magnetic moment, and also a test of the CPT invariance. Monte Carlo simulations predict that the antihydrogen ground-state hyperfine splitting can be determined with a relative precision of better than {approx} 10{sup - 6}. The first preliminary measurements of the hyperfine transitions will start in 2011.
Lower ground state due to counter-rotating wave interaction in trapped ion system
Liu, T; Feng, M
2007-01-01
We consider a single ion confined in a trap under radiation of two traveling waves of lasers. In the strong-excitation regime and without the restriction of Lamb-Dicke limit, the Hamiltonian of the system is similar to a driving Jaynes-Cummings model without rotating wave approximation (RWA). The approach we developed enables us to present a complete eigensolutions, which makes it available to compare with the solutions under the RWA. We find that, the ground state in our non-RWA solution is energically lower than the counterpart under the RWA. If we have the ion in the ground state, it is equivalent to a spin dependent force on the trapped ion. Discussion is made for the difference between the solutions with and without the RWA, and for the relevant experimental test, as well as for the possible application in quantum information processing.
Classical and quantum filaments in the ground state of trapped dipolar Bose gases
Cinti, Fabio; Boninsegni, Massimo
2017-07-01
We study, by quantum Monte Carlo simulations, the ground state of a harmonically confined dipolar Bose gas with aligned dipole moments and with the inclusion of a repulsive two-body potential of varying range. Two different limits can clearly be identified, namely, a classical one in which the attractive part of the dipolar interaction dominates and the system forms an ordered array of parallel filaments and a quantum-mechanical one, wherein filaments are destabilized by zero-point motion, and eventually the ground state becomes a uniform cloud. The physical character of the system smoothly evolves from classical to quantum mechanical as the range of the repulsive two-body potential increases. An intermediate regime is observed in which ordered filaments are still present, albeit forming different structures from the ones predicted classically; quantum-mechanical exchanges of indistinguishable particles across different filaments allow phase coherence to be established, underlying a global superfluid response.
Universal Wave-Function Overlap and Universal Topological Data from Generic Gapped Ground States.
Moradi, Heidar; Wen, Xiao-Gang
2015-07-17
We propose a way-universal wave-function overlap-to extract universal topological data from generic ground states of gapped systems in any dimensions. Those extracted topological data might fully characterize the topological orders with a gapped or gapless boundary. For nonchiral topological orders in (2+1)D, these universal topological data consist of two matrices S and T, which generate a projective representation of SL(2,Z) on the degenerate ground state Hilbert space on a torus. For topological orders with a gapped boundary in higher dimensions, these data constitute a projective representation of the mapping class group MCG(M^{d}) of closed spatial manifold M^{d}. For a set of simple models and perturbations in two dimensions, we show that these quantities are protected to all orders in perturbation theory. These overlaps provide a much more powerful alternative to the topological entanglement entropy and allow for more efficient numerical implementations.
ON THE RADIAL GROUND STATE OFP-LAPLACIAN EQUATION WITH GRADIENT TERM PERTURBATION
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
In this paper,authors consider the existence,uniqueness and nonexistence of the radial ground state to the following p-Laplacian equation:△pu+uq-|Dulσ=0,x ∈Rn,where 2≤p
High-precision quadrupole moment reveals significant intruder component in 20 13 33Al ground state
Heylen, H.; De Rydt, M.; Neyens, G.; Bissell, M. L.; Caceres, L.; Chevrier, R.; Daugas, J. M.; Ichikawa, Y.; Ishibashi, Y.; Kamalou, O.; Mertzimekis, T. J.; Morel, P.; Papuga, J.; Poves, A.; Rajabali, M. M.; Stödel, C.; Thomas, J. C.; Ueno, H.; Utsuno, Y.; Yoshida, N.; Yoshimi, A.
2016-09-01
The electric quadrupole moment of the 20 13 33Al ground state, located at the border of the island of inversion, was obtained using continuous-beam β -detected nuclear quadrupole resonance (β -NQR). From the measured quadrupole coupling constant νQ=2.31 (4 ) MHz in an α -Al2O3 crystal, a precise value for the electric quadrupole moment is extracted: 33Al>Qs 141 (3 ) mb. A comparison with large-scale shell model calculations shows that 33Al has at least 50% intruder configurations in the ground state wave function, favoring the excitation of two neutrons across the N =20 shell gap. 33Al therefore clearly marks the gradual transition north of the deformed Na and Mg nuclei towards the normal Z ≥14 isotopes.
Ground State Density Distribution of Bose-Fermi Mixture in a One-Dimensional Harmonic Trap
Institute of Scientific and Technical Information of China (English)
HAO Ya-Jiang
2011-01-01
By the density-functional calculation we investigate the ground-state properties of Bose-Fermi mixture confined in one-dimensional harmonic traps. The homogeneous mixture of bosons and polarized fermions with contact interaction can be exactly solved by the Bethe-ansatz method. After giving the exact formula of ground state energy density, we employ the local-density approximation to determine the density distribution of each component. It is shown that with the increase in interaction, the total density distribution evolves to Fermi-like distribution and the system exhibits phase separation between two components when the interaction is strong enough but finite. While in the infinite interaction limit both bosons and fermions display the completely same Fermi-like distributions and phase separation disappears.
Simulated Annealing for Ground State Energy of Ionized Donor Bound Excitons in Semiconductors
Institute of Scientific and Technical Information of China (English)
YANHai-Qing; TANGChen; LIUMing; ZHANGHao; ZHANGGui-Min
2004-01-01
We present a global optimization method, called the simulated annealing, to the ground state energies of excitons. The proposed method does not require the partial derivatives with respect to each variational parameter or solving an eigenequation, so the present method is simpler in software programming than the variational method,and overcomes the major difficulties. The ground state energies of ionized-donor-bound excitons (D+,X) have beencal culated variationally for all values of effective electron-to-hole mass ratio σ. They are compared with those obtained by the variational method. The results obtained demonstrate that the proposed method is simple, accurate, and has more advantages than the traditional methods in calculation.
Simulated Annealing for Ground State Energy of Ionized Donor Bound Excitons in Semiconductors
Institute of Scientific and Technical Information of China (English)
YAN Hai-Qing; TANG Chen; LIU Ming; ZHANG Hao; ZHANG Gui-Min
2004-01-01
We present a global optimization method, called the simulated annealing, to the ground state energies of excitons. The proposed method does not require the partial derivatives with respect to each variational parameter or solving an eigenequation, so the present method is simpler in software programming than the variational method,and overcomes the major difficulties. The ground state energies of ionized-donor-bound excitons (D+, X) have been calculated variationally for all values of effective electron-to-hole mass ratio σ. They are compared with those obtained by the variational method. The results obtained demonstrate that the proposed method is simple, accurate, and has more advantages than the traditional methods in calculation.
Ground-State Phase Diagram of S = 2 Heisenberg Chains with Alternating Single-Site Anisotropy
Hida, Kazuo
2014-03-01
The ground-state phase diagram of S = 2 antiferromagnetic Heisenberg chains with coexisting uniform and alternating single-site anisotropies is investigated by the numerical exact diagonalization and density matrix renormalization group methods. We find the Haldane, large-D, Néel, period-doubled Néel, gapless spin fluid, quantized and partial ferrimagnetic phases. The Haldane phase is limited to the close neighborhood of the isotropic point. Within numerical accuracy, the transition from the gapless spin-fluid phase to the period-doubled Néel phase is a direct transition. Nevertheless, the presence of a narrow spin-gap phase between these two phases is suggested on the basis of the low-energy effective theory. The ferrimagnetic ground state is present in a wide parameter range. This suggests the realization of magnetized single-chain magnets with a uniform spin magnitude by controlling the environment of each magnetic ion without introducing ferromagnetic interactions.
Extremal Optimization for Ground States of the Sherrington-Kirkpatrick Spin Glass with Levy Bonds
Boettcher, Stefan
2013-03-01
Using the Extremal Optimization heuristic (EO),[3] ground states of the SK-spin glass are studied with bonds J distributed according to a Levy distribution P (J) ~ 1 /| J | 1 + α with | J | > 1 and 1 model with Gaussian bonds.[4] We find that the energies attain universally the Parisi-energy of the SK when the second moment of P(J) exists (α > 2). They compare favorably with recent one-step replica symmetry breaking predictions well below α = 2 . Near α = 2 , the simulations deviate significantly from theoretical expectations. The finite-size corrections exponent ω decays from the putative SK value ωSK =2/3 already well above α = 2 . The exponent ρ for the scaling of ground state energy fluctuations with system size decays linearly from its SK value for decreasing α and vanishes at α = 1 . Supported through NSF grant DMR-#1207431
High-precision quadrupole moment reveals significant intruder component in 33Al20 ground state
Heylen, H; Neyens, G; Bissell, M L; Caceres, L; Chevrier, R; Daugas, J M; Ichikawa, Y; Ishibashi, Y; Kamalou, O; Mertzimekis, T J; Morel, P; Papuga, J; Poves, A; Rajabali, M M; Stodel, C; Thomas, J C; Ueno, H; Utsuno, Y; Yoshida, N; Yoshimi, A
2016-01-01
The electric quadrupole moment of the 33Al20 ground state, located at the border of the island of inversion, was obtained using continuous-beam beta-detected nuclear quadrupole resonance (beta-NQR). From the measured quadrupole coupling constant Q = 2.31(4) MHz in an alpha-Al2O3 crystal, a precise value for the electric quadrupole moment is extracted: Qs= 141(3) mb. A comparison with large-scale shell model calculations shows that 33Al has at least 50% intruder configurations in the ground state wave function, favoring the excitation of two neutrons across the N = 20 shell gap. 33Al therefore clearly marks the gradual transition north of the deformed Na and Mg nuclei towards the normal Z>14 isotopes.
Jaouadi, Amine; Lefebvre, Roland; Atabek, Osman
2017-06-01
A semiclassical model supporting the destructive interference interpretation of zero-width resonances (ZWRs) is extended to wavelengths inducing c--type curve crossing situations in Na2 strong-field dissociation. This opens the possibility to get critical couples of wavelengths λ and field intensities I to reach ZWRs associated with the ground vibrationless level v =0 , that, contrary to other vibrational states (v >0 ), is not attainable for the commonly referred c+-type crossings. The morphology of such ZWRs in the laser (I ,λ ) parameter plane and their usefulness in filtration strategies aiming at molecular cooling down to the ground v =0 state are examined within the frame of an adiabatic transport scheme.
Ercolessi, E; Morandi, G; Mukunda, N
2001-01-01
We analyze the geometric aspects of unitary evolution of general states for a multilevel quantum system by exploiting the structure of coadjoint orbits in the unitary group Lie algebra. Using the same method in the case of SU(3) we study the effect of degeneracies on geometric phases for three-level systems. This is shown to lead to a highly nontrivial generalization of the result for two-level systems in which degeneracy results in a "monopole" structure in parameter space. The rich structures that arise are related to the geometry of adjoint orbits in SU(3). The limiting case of a two-level degeneracy in a three-level system is shown to lead to the known monopole structure.
Triplet-singlet conversion in ultracold Cs$_2$ and production of ground state molecules
Bouloufa, Nadia; Aymar, Mireille; Dulieu, Olivier
2010-01-01
We propose a process to convert ultracold metastable Cs$_2$ molecules in their lowest triplet state into (singlet) ground state molecules in their lowest vibrational levels. Molecules are first pumped into an excited triplet state, and the triplet-singlet conversion is facilitated by a two-step spontaneous decay through the coupled $A^{1}\\Sigma_{u}^{+} \\sim b ^{3}\\Pi_{u}$ states. Using spectroscopic data and accurate quantum chemistry calculations for Cs$_2$ potential curves and transition dipole moments, we show that this process has a high rate and competes favorably with the single-photon decay back to the lowest triplet state. In addition, we demonstrate that this conversion process represents a loss channel for vibrational cooling of metastable triplet molecules, preventing an efficient optical pumping cycle down to low vibrational levels.
Quantum spin liquid ground states of the Heisenberg-Kitaev model on the triangular lattice
Kos, Pavel; Punk, Matthias
2017-01-01
We study quantum disordered ground states of the two-dimensional Heisenberg-Kitaev model on the triangular lattice using a Schwinger boson approach. Our aim is to identify and characterize potential gapped quantum spin liquid phases that are stabilized by anisotropic Kitaev interactions. For antiferromagnetic Heisenberg and Kitaev couplings and sufficiently small spin S , we find three different symmetric Z2 spin liquid phases, separated by two continuous quantum phase transitions. Interestingly, the gap of elementary excitations remains finite throughout the transitions. The first spin liquid phase corresponds to the well-known zero-flux state in the Heisenberg limit, which is stable with respect to small Kitaev couplings and develops 120∘ order in the semiclassical limit at large S . In the opposite Kitaev limit, we find a different spin liquid ground state, which is a quantum disordered version of a magnetically ordered state with antiferromagnetic chains, in accordance with results in the classical limit. Finally, at intermediate couplings, we find a spin liquid state with unusual spin correlations. Upon spinon condensation, this state develops Bragg peaks at incommensurate momenta in close analogy to the magnetically ordered Z2 vortex crystal phase, which has been analyzed in recent theoretical works.
Ground state study of the thin ferromagnetic nano-islands for artificial spin ice arrays
Energy Technology Data Exchange (ETDEWEB)
Vieira Júnior, D. S., E-mail: damiao.vieira@ifsudestemg.edu.br [Departamento Acadêmico de Matemática, Física e Estatística, Instituto Federal de Educação, Ciência e Tecnologia do Sudeste de Minas Gerais - Câmpus Rio Pomba, Rio Pomba, Minas Gerais 36180-000 (Brazil); Departamento de Física, Laboratório de Simulação Computacional, Universidade Federal de Juiz de Fora, Juiz de Fora, Minas Gerais 36036-330 (Brazil); Leonel, S. A., E-mail: sidiney@fisica.ufjf.br; Dias, R. A., E-mail: radias@fisica.ufjf.br; Toscano, D., E-mail: danilotoscano@fisica.ufjf.br; Coura, P. Z., E-mail: pablo@fisica.ufjf.br; Sato, F., E-mail: sjfsato@fisica.ufjf.br [Departamento de Física, Laboratório de Simulação Computacional, Universidade Federal de Juiz de Fora, Juiz de Fora, Minas Gerais 36036-330 (Brazil)
2014-09-07
In this work, we used numerical simulations to study the magnetic ground state of the thin elongated (elliptical) ferromagnetic nano-islands made of Permalloy. In these systems, the effects of demagnetization of dipolar source generate a strong magnetic anisotropy due to particle shape, defining two fundamental magnetic ground state configurations—vortex or type C. To describe the system, we considered a model Hamiltonian in which the magnetic moments interact through exchange and dipolar potentials. We studied the competition between the vortex states and aligned states—type C—as a function of the shape of each elliptical nano-islands and constructed a phase diagram vortex—type C state. Our results show that it is possible to obtain the elongated nano-islands in the C-state with aspect ratios less than 2, which is interesting from the technological point of view because it will be possible to use smaller islands in spin ice arrays. Generally, the experimental spin ice arrangements are made with quite elongated particles with aspect ratio approximately 3 to ensure the C-state.
Ground-state solution for a class of biharmonic equations including critical exponent
Liu, Hongliang; Chen, Haibo
2015-12-01
In this paper, we study the following biharmonic equations Δ^2 u = λ{|u|^{2^{astast}(s)-2}u/|x|^s} + β a(x)|u|^{r-2}u,quad xin {{R}}^N. Under some suitable assumptions of {λ}, {β} and {a(x)}, the existence of ground-state solution and nonexistence of nontrivial solution are obtained by using variational methods. Moreover, the phenomenon of concentration of solutions is also explored.
The role of correlation in the ground state energy of confined helium atom
Energy Technology Data Exchange (ETDEWEB)
Aquino, N. [Departamento de Física, Universidad Autónoma Metropolitana-Iztapalapa, Apartado Postal 55-534, 09340 México Distrito Federal (Mexico)
2014-01-14
We analyze the ground state energy of helium atom confined by spherical impenetrable walls, and the role of the correlation energy in the total energy. The confinement of an atom in a cavity is one way in which we can model the effect of the external pressure on an atom. The calculations of energy of the system are carried out by the variational method. We find that the correlation energy remains almost constant for a range values of size of the boxes analyzed.
Ground state Lamb-shift of heavy hydrogen-like ions: status and perspectives
Energy Technology Data Exchange (ETDEWEB)
Stoehlker, Th., E-mail: t.stoehlker@gsi.de; Beyer, H. F.; Gumberidze, A.; Kumar, A.; Liesen, D.; Reuschl, R.; Spillmann, U.; Trassinelli, M. [GSI Darmstadt (Germany)
2006-09-15
We present the current status in experimental investigations of the heaviest hydrogen-like systems at the Experimental Storage Ring (ESR) at GSI Darmstadt. Together with the most recent theoretical predictions the present experimental result provides a test of the leading quantum electrodynamical (QED) contributions on a percent level. In addition, the planned future experimental studies and related developments devoted to high-resolution spectroscopy of the ground-state in high-Z hydrogen-like systems are reviewed.
Ground state spin 0$^+$ dominance of many-body systems with random interactions and related topics
Arima, A; Zhao, Y M
2003-01-01
In this talk we shall show our recent results in understanding the spin$^{\\rm parity}$ 0$^+$ ground state (0 g.s.) dominance of many-body systems. We propose a simple approach to predict the spin $I$ g.s. probabilities which does not require the diagonalization of a Hamiltonian with random interactions. Some findings related to the 0 g.s. dominance will also be discussed.
Masses and magnetic moments of ground-state baryons in covariant baryon chiral perturbation theory
Geng, L S; Alvarez-Ruso, L; Vicente-Vacas, M J
2012-01-01
We report on some recent developments in our understanding of the light-quark mass dependence and the SU(3) flavor symmetry breaking corrections to the magnetic moments of the ground-state baryons in a covariant formulation of baryon chiral perturbation theory, the so-called EOMS formulation. We show that this covariant ChPT exhibits some promising features compared to its heavy-baryon and infrared counterparts.
Prevalence of Campylobacter species in ground water in Sokoto, Sokoto state, Nigeria
Agatha N. Ugboma; Muhammed D. Salihu; Abdullahi A. Magaji; Abubakar, Mikail B.
2013-01-01
Aim: The present study was conducted to determine the presence and prevalence of Campylobacter species in ground water in Sokoto, Sokoto State. Materials and Methods: The prevalence of Campylobacter species was determined by collecting a total of 74 water samples from wells in Sokoto over a period of four months from May to August 2011 and analyzed using cultural isolation techniques and biochemical characterization. Results: Totally 39 (52.70%) water samples were Campylobacter positive. The ...
Perturbative analysis of the ground-state wavefunctions of the quantum anharmonic oscillators
Energy Technology Data Exchange (ETDEWEB)
Xie Qiongtao [Department of Physics and Key Laboratory of Low-Dimensional Quantum Structure and Quantum Control of Ministry of Education, Hunan Normal University, Changsha 410081 (China)], E-mail: xieqiongtao@yahoo.cn
2009-10-23
We investigate the perturbative expansions of the ground-state wavefunctions of the quantum anharmonic oscillators. With an appropriate change of spatial scale, the weak-coupling Schroedinger equation is transformed to an equivalent strong-coupling one. The Friedberg-Lee-Zhao method is applied to obtain the improved perturbative expansions. These perturbative expansions give a correction to the WKB results for large spatial distances, and reproduce the conventional weak-coupling results for small spatial distances.
Perturbative analysis of the ground-state wavefunctions of the quantum anharmonic oscillators
Xie, Qiong-Tao
2009-10-01
We investigate the perturbative expansions of the ground-state wavefunctions of the quantum anharmonic oscillators. With an appropriate change of spatial scale, the weak-coupling Schrödinger equation is transformed to an equivalent strong-coupling one. The Friedberg-Lee-Zhao method is applied to obtain the improved perturbative expansions. These perturbative expansions give a correction to the WKB results for large spatial distances, and reproduce the conventional weak-coupling results for small spatial distances.
Diagrammatic perturbation theory applied to the ground state of the water molecule
Silver, D. M.; Wilson, S.
1977-01-01
The diagrammatic many-body perturbation theory is applied to the ground state of the water molecule within the algebraic approximation. Using four different basis sets, the total energy, the equilibrium OH bond length, and the equilibrium HOH bond angle are examined. The latter is found to be a particularly sensitive test of the convergence of perturbation expansions. Certain third-order results, which incorporate all two-, three-, and four-body effects, show evidence of good convergence properties.
Ground-State Bands of Fm and No Isotopes in Cluster Model
Institute of Scientific and Technical Information of China (English)
XU Chang; REN Zhong-Zhou
2006-01-01
We investigate the ground-state rotational bands of nuclei with Z ≥ 100 using cluster model proposed by Buck et al. [Phys. Rev. Lett. 94 (2005) 202501]. The core-cluster decomposition of each nucleus is determined by the corresponding electric quadrupole transition strength B(E2 : 2+ → 0+). The theoretical spectra of fermium and nobelium isotopes are compared with available experimental data. Good agreement between model and data is obtained.
A centred, elongated "ferric tetrahedron" with an S= 15/2 spin ground state.
Tabernor, James; Jones, Leigh F; Heath, Sarah L; Muryn, Chris; Aromi, Guillem; Ribas, Joan; Brechin, Euan K; Collison, David
2004-04-07
The reaction of anhydrous FeCl(3) with 1H-benzotriazole-1-methanol (Bta-CH(2)OH) in MeOH produces the pentanuclear complex [Fe(5)O(2)(OMe)(2)(Bta)(4)(BtaH)(MeOH)(5)Cl(5)], containing a distorted tetrahedron of four Fe ions centred on a fifth. The central Fe is antiferromagnetically coupled to the peripheral Fe ions resulting in an S= 15/2 spin ground state.
Ground state and orbital stability for the NLS equation on a general starlike graph with potentials
Cacciapuoti, Claudio; Finco, Domenico; Noja, Diego
2017-08-01
We consider a nonlinear Schrödinger equation (NLS) posed on a graph (or network) composed of a generic compact part to which a finite number of half-lines are attached. We call this structure a starlike graph. At the vertices of the graph interactions of δ-type can be present and an overall external potential is admitted. Under general assumptions on the potential, we prove that the NLS is globally well-posed in the energy domain. We are interested in minimizing the energy of the system on the manifold of constant mass (L 2-norm). When existing, the minimizer is called ground state and it is the profile of an orbitally stable standing wave for the NLS evolution. We prove that a ground state exists for sufficiently small masses whenever the quadratic part of the energy admits a simple isolated eigenvalue at the bottom of the spectrum (the linear ground state). This is a wide generalization of a result previously obtained for a star-graph with a single vertex. The main part of the proof is devoted to prove the concentration compactness principle for starlike structures; this is non trivial due to the lack of translation invariance of the domain. Then we show that a minimizing, bounded, H 1 sequence for the constrained NLS energy with external linear potentials is in fact convergent if its mass is small enough. Moreover we show that the ground state bifurcates from the vanishing solution at the bottom of the linear spectrum. Examples are provided with a discussion of the hypotheses on the linear part.
Stable π-Extended p -Quinodimethanes: Synthesis and Tunable Ground States
Zeng, Zebing
2014-12-18
© 2014 The Chemical Society of Japan and Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. p-Quinodimethane (p-QDM) is a highly reactive hydrocarbon showing large biradical character in the ground state. It has been demonstrated that incorporation of the p-QDM moiety into an aromatic hydrocarbon framework could lead to new π-conjugated systems with significant biradical character and unique optical, electronic and magnetic properties. On the other hand, the extension of p-QDM is expected to result in molecules with even larger biradical character and higher reactivity. Therefore, the synthesis of stable π-extended p-QDMs is very challenging. In this Personal Account we will briefly discuss different stabilizing strategies and synthetic methods towards stable π-extended p-QDMs with tunable ground states and physical properties, including two types of polycyclic hydrocarbons: (1) tetrabenzo-Tschitschibabin\\'s hydrocarbons, and (2) tetracyano-rylenequinodimethanes. We will discuss how the aromaticity, substituents and steric hindrance play important roles in determining their ground states and properties. Incorporation of the p-quinodimethane moiety into aromatic hydrocarbon frameworks can lead to new π-conjugated systems with significant biradical character and unique optical, electronic and magnetic properties. Furthermore, the extension of p-QDM is expected to result in molecules with even larger biradical character and higher reactivity. In this Personal Account, different stabilizing strategies and synthetic methods towards stable π-extended p-QDMs with tunable ground states and physical properties are briefly discussed, including the roles of aromaticity, substituents and steric hindrance.
Ground-State Ionization Potentials for Lithium through Neon Isoelectronic Sequences with Z=37-82
Institute of Scientific and Technical Information of China (English)
HUANG Jie; JIANG Gang; ZHAO Qian
2006-01-01
The ground-state ionization potentials of different isoelectronic sequences are calculated systemically with the multi-configuration Dirac-Fock method.The relativistic corrections,Breit and QED effects are included in the calculation.These results are compared with the scanty existing theoretical and experimental data in the literature.Analytical expressions are obtained for expressing our theoretical data along the different sequences.
Massless ground state for a compact SU(2 matrix model in 4D
Directory of Open Access Journals (Sweden)
Lyonell Boulton
2015-09-01
Full Text Available We show the existence and uniqueness of a massless supersymmetric ground state wavefunction of a SU(2 matrix model in a bounded smooth domain with Dirichlet boundary conditions. This is a gauge system and we provide a new framework to analyze the quantum spectral properties of this class of supersymmetric matrix models subject to constraints which can be generalized for arbitrary number of colors.
Directory of Open Access Journals (Sweden)
Xia Liu
2017-02-01
Full Text Available The discrete nonlinear Schrodinger equation is a nonlinear lattice system that appears in many areas of physics such as nonlinear optics, biomolecular chains and Bose-Einstein condensates. In this article, we consider a class of discrete nonlinear Schrodinger equations with unbounded potentials. We obtain some new sufficient conditions on the multiplicity results of ground state solutions for the equations by using the symmetric mountain pass lemma. Recent results in the literature are greatly improved.
Eigenfunctions of Five-Qubit XX Chain and Ground State Concurrence
Institute of Scientific and Technical Information of China (English)
LING Yin-Sheng
2008-01-01
Use Jordan-Wigner transformation the eigenstates and eigenenergies of five qubits XX chain including external magnetic field are obtained. The concurrences Co,1 and C0,2 of ground state are obtained. For the ferromagnetic,when [((√)5-1)/2]|J|
Creation of ultracold $^{87}$RbCs molecules in the rovibrational ground state
Molony, Peter K; Ji, Zhonghua; Lu, Bo; Köppinger, Michael P; Sueur, C Ruth Le; Blackley, Caroline L; Hutson, Jeremy M; Cornish, Simon L
2014-01-01
We report the creation of a sample of over 1000 ultracold $^{87}$RbCs molecules in the lowest rovibrational ground state, from an atomic mixture of $^{87}$Rb and Cs, by magnetoassociation on an interspecies Feshbach resonance followed by stimulated Raman adiabatic passage (STIRAP). We measure the binding energy of the RbCs molecule to be $h c \\times 3811.576(1)$ cm$^{-1}$ and the $|\
Ground State of the Universe and the Cosmological Constant. A Nonperturbative Analysis.
Husain, Viqar; Qureshi, Babar
2016-02-12
The physical Hamiltonian of a gravity-matter system depends on the choice of time, with the vacuum naturally identified as its ground state. We study the expanding Universe with scalar field in the volume time gauge. We show that the vacuum energy density computed from the resulting Hamiltonian is a nonlinear function of the cosmological constant and time. This result provides a new perspective on the relation between time, the cosmological constant, and vacuum energy.
The Potential Energy Surface for the Electronic Ground State of H 2Se Derived from Experiment
Jensen, P.; Kozin, I. N.
1993-07-01
The present paper reports a determination of the potential energy surface for the electronic ground state of the hydrogen selenide molecule through a direct least-squares fitting to experimental data using the MORBID (Morse oscillator rigid bender internal dynamics) approach developed by P. Jensen [ J. Mol. Spectrosc.128, 478-501 (1988); J. Chem. Soc. Faraday Trans. 284, 1315-1340 (1988)]. We have fitted a selection of 303 rotation-vibration energy spacings of H 280Se, D 280Se, and HD 80Se involving J ≤ 5 with a root-mean-square deviation of 0.0975 cm -1 for the rotational energy spacings and 0.268 cm -1 for the vibrational spacings. In the fitting, 14 parameters were varied. On the basis of the fitted potential surface we have studied the cluster effect in the vibrational ground state of H 2Se, i.e., the formation of nearly degenerate, four-member groups of rotational energy levels [see I. N. Kozin, S. Klee, P. Jensen, O. L. Polyansky, and I. M. Pavlichenkov. J. Mol. Spectrosc., 158, 409-422 (1993), and references therein]. The cluster formation becomes more pronounced with increasing J. For example, four-fold clusters formed in the vibrational ground state of H 280Se at J = 40 are degenerate to within a few MHz. Our predictions of the D 280Se energy spectrum show that for this molecule, the cluster formation is displaced towards higher J values than arc found for H 280Se. In the vibrational ground state, the qualitative deviation from the usual rigid rotor picture starts at J = 12 for H 280Se and at J = 18 for D 280Se, in full agreement with predictions from semiclassical theory. An interpretation of the cluster eigenstates is discussed.
Ground-state diagrams for lattice-gas models of catalytic CO oxidation
Directory of Open Access Journals (Sweden)
I.S.Bzovska
2007-01-01
Full Text Available Based on simple lattice models of catalytic carbon dioxide synthesis from oxygen and carbon monoxide, phase diagrams are investigated at temperature T=0 by incorporating the nearest-neighbor interactions on a catalyst surface. The main types of ground-state phase diagrams of two lattice models are classified describing the cases of clean surface and surface containing impurities. Nonuniform phases are obtained and the conditions of their existence dependent on the interaction parameters are established.
Ab initio organic chemistry : a survey of ground- and excited states and aromaticity
Havenith, R.W.A.
2001-01-01
This thesis describes the application of quantum mechanical methods on organic chemistry. The ground- and excited states of functionalized oligo(cyclohexylidenes) have been explored as in function of chain length, conformation and substitution. VB theory has been used to study the effect of cyclopentafusion on pyrene on its aromatic characteristics. Finally, the relevant part of the C6 H6 potentional energy surface has been explored to shed light on the reaction mechanism of the thermal elect...
Ground-state energy of the electron liquid in ultrathin wires.
Fogler, Michael M
2005-02-11
The ground-state energy and the density correlation function of the electron liquid in a thin one-dimensional wire are computed. The calculation is based on an approximate mapping of the problem with a realistic Coulomb interaction law onto exactly solvable models of mathematical physics. This approach becomes asymptotically exact in the limit of a small wire radius but remains numerically accurate even for modestly thin wires.
Ground state phase diagram of the half-filled bilayer Hubbard model
Golor, Michael; Reckling, Timo; Classen, Laura; Scherer, Michael M.; Wessel, Stefan
2014-01-01
Employing a combination of functional renormalization group calculations and projective determinantal quantum Monte Carlo simulations, we examine the Hubbard model on the square lattice bilayer at half filling. From this combined analysis, we obtain a comprehensive account on the ground state phase diagram with respect to the extent of the system's metallic and (antiferromagnetically ordered) Mott-insulating as well as band-insulating regions. By means of an unbiased functional renormalizatio...
Villegas, Javier E.
2009-03-01
Superconducting/Ferromagnetic (S/F) hybrids exhibit a plethora of induced effects and novel physical properties, due to the interplay between the competing S and F orders. We will show a few examples of those, in a series of experiments on a simple hybrid system: a S thin film with an array of F nanodots. Changing the array geometry, the nanodots size or their magnetic-state allows to investigate a large variety of physical phenomena. We will focus on two of them: flux pinning effects and stray-magnetic-field induced manipulation of superconductivity. We will firstly consider geometry induced effects; in particular, we will compare the pinning properties of periodic, quasiperiodic, and fractal arrays [1]. Secondly, we will discuss the effects induced by particular nanodot magnetic-states. We will show experiments on the interaction between flux quanta and nanodot magnetic vortices, which can be used to obtain switchable flux pinning potentials [2]. Finally, we will describe an experiment in which the magnetic reversal events of the nanodot magnetic vortices are imprinted into the transport properties of a superconducting thin film [3]. This yields a very unusual hysteretic magnetoresistance. This effect is induced by the stray magnetic fields from the nanodots, which drive the superconducting-to-normal transition of the hybrid depending on the magnetic history. [4pt] [1] J.E. Villegas et al., Phys. Rev. Lett. 97, 027002 (2006). [0pt] [2] J.E. Villegas et al., Phys. Rev. B 77, 134510 (2008). [0pt] [3] J.E. Villegas et al., Phys. Rev. Lett. 99, 227001 (2007).
Zheng, Greg Y.; Rillema, D. Paul; DePriest, Jeff; Woods, Clifton
1998-07-13
Direct access to the triplet emitting state from the ground state is observed for Pt(II) complexes containing heterocyclic (CwedgeC', CwedgeN, NwedgeN') and bis(diphenylphosphino)alkane (PwedgeP') ligands. Extinction coefficients for such transitions are in the range 4-25 M(-)(1) cm(-)(1). Emission quantum yields resulting from singlet-to-triplet excitation are as high as 61-77 times the emission quantum yields resulting from singlet-to-singlet excitation at 296 K. The intersystem crossing quantum yield from the singlet excited state to triplet emitting state is lower than 2% at 296 K but is greatly enhanced at 77 K. The forbidden electronic transition observed for Pt(II) complexes is attributed to result from spin-orbit coupling due to the presence of Pt(II) in the skeleton structure. The importance of excitation spectra on the computation of emission quantum yields is discussed.
Hubbard models with nearly flat bands: Ground-state ferromagnetism driven by kinetic energy
Müller, Patrick; Richter, Johannes; Derzhko, Oleg
2016-04-01
We consider the standard repulsive Hubbard model with a flat lowest-energy band for two one-dimensional lattices (diamond chain and ladder) as well as for a two-dimensional lattice (bilayer) at half filling of the flat band. The considered models do not fall in the class of Mielke-Tasaki flat-band ferromagnets, since they do not obey the connectivity conditions. However, the ground-state ferromagnetism can emerge, if the flat band becomes dispersive. To study this kinetic-energy-driven ferromagnetism we use perturbation theory and exact diagonalization of finite lattices. We find as a typical scenario that small and moderate dispersion may lead to a ferromagnetic ground state for sufficiently large on-site Hubbard repulsion U >Uc , where Uc increases monotonically with the acquired bandwidth. However, we also observe for some specific parameter cases, that (i) ferromagnetism appears at already very small Uc, (ii) ferromagnetism does not show up at all, (iii) the critical on-site repulsion Uc is a nonmonotonic function of the bandwidth, or that (iv) a critical bandwidth is needed to open the window for ground-state ferromagnetism.
High spin polarization and the origin of unique ferromagnetic ground state in CuFeSb
Sirohi, Anshu; Singh, Chandan K.; Thakur, Gohil S.; Saha, Preetha; Gayen, Sirshendu; Gaurav, Abhishek; Jyotsna, Shubhra; Haque, Zeba; Gupta, L. C.; Kabir, Mukul; Ganguli, Ashok K.; Sheet, Goutam
2016-06-01
CuFeSb is isostructural to the ferro-pnictide and chalcogenide superconductors and it is one of the few materials in the family that are known to stabilize in a ferromagnetic ground state. Majority of the members of this family are either superconductors or antiferromagnets. Therefore, CuFeSb may be used as an ideal source of spin polarized current in spin-transport devices involving pnictide and the chalcogenide superconductors. However, for that the Fermi surface of CuFeSb needs to be sufficiently spin polarized. In this paper we report direct measurement of transport spin polarization in CuFeSb by spin-resolved Andreev reflection spectroscopy. From a number of measurements using multiple superconducting tips we found that the intrinsic transport spin polarization in CuFeSb is high (˜47%). In order to understand the unique ground state of CuFeSb and the origin of large spin polarization at the Fermi level, we have evaluated the spin-polarized band structure of CuFeSb through first principles calculations. Apart from supporting the observed 47% transport spin polarization, such calculations also indicate that the Sb-Fe-Sb angles and the height of Sb from the Fe plane are strikingly different for CuFeSb than the equivalent parameters in other members of the same family thereby explaining the origin of the unique ground state of CuFeSb.
Uniqueness and symmetry of ground states for the L^2-critical boson star equation
Frank, Rupert L
2009-01-01
We prove uniqueness of ground state solutions for the $L^2$-critical boson star equation $\\sqrt{-\\Delta} u - \\big (|x|^{-1} \\ast |u|^2 \\big) u = -u$ in $\\R^3$, thereby settling a uniqueness conjecture of Lieb and Yau in [CMP \\textbf{112} (1987), 147--174] for the massless case. Our proof blends variational arguments with an harmonic extension to the halfspace $\\R^4_+ = \\R^3 \\times \\R_+$. Apart from uniqueness, we also establish the radial symmetry of ground state solutions (up to translations) as well as the nondegeneracy of the linearization. Our results provide an indispensable basis for the blowup analysis for the time-dependent $L^2$-critical massless boson star equation. The main result of this paper can be generalized to different fractional powers $(-\\Delta)^s$ and dimensions $d \\geq 3$. In particular, it can be regarded as the first non-perturbative uniqueness result for ground states of fractional elliptic nonlinear equations in higher space dimensions, beyond the conformally invariant case of Sobole...
Three-body correlations in the ground-state decay of 26O
Kohley, Z; Christian, G; DeYoung, P A; Finck, J E; Frank, N; Luther, B; Lunderberg, E; Jones, M; Mosby, S; Smith, J K; Spyrou, A; Thoennessen, M
2015-01-01
Background: Theoretical calculations have shown that the energy and angular correlations in the three-body decay of the two-neutron unbound O26 can provide information on the ground-state wave function, which has been predicted to have a dineutron configuration and 2n halo structure. Purpose: To use the experimentally measured three-body correlations to gain insight into the properties of O26, including the decay mechanism and ground-state resonance energy. Method: O26 was produced in a one-proton knockout reaction from F27 and the O24+n+n decay products were measured using the MoNA-Sweeper setup. The three-body correlations from the O26 ground-state resonance decay were extracted. The experimental results were compared to Monte Carlo simulations in which the resonance energy and decay mechanism were varied. Results: The measured three-body correlations were well reproduced by the Monte Carlo simulations but were not sensitive to the decay mechanism due to the experimental resolutions. However, the three-body...
Structural Studies of Metastable and Ground State Vortex Lattice Domains in MgB2
de Waard, E. R.; Kuhn, S. J.; Rastovski, C.; Eskildsen, M. R.; Leishman, A.; Dewhurst, C. D.; Debeer-Schmitt, L.; Littrell, K.; Karpinski, J.; Zhigadlo, N. D.
2015-03-01
Small-angle neutron scattering (SANS) studies of the vortex lattice (VL) in the type-II superconductor MgB2 have revealed an unprecedented degree of metastability that is demonstrably not due to vortex pinning, [C. Rastovski et al . , Phys. Rev. Lett. 111, 107002 (2013)]. Application of an AC magnetic field to drive the VL to the ground state revealed a two-step power law behavior, indicating a slow nucleation of ground state domains followed by a faster growth. The dependence on the number of applied AC cycles is reminiscent of jamming of soft, frictionless spheres. Here, we report on detailed structural studies of both metastable and ground state VL domains. These include measurements of VL correlation lengths as well as spatially resolved SANS measurements showing the VL domain distribution within the MgB2 single crystal. We discuss these results and how they may help to resolve the mechanism responsible for stabilizing the metastable VL phases. This work is supported by the U.S. Department of Energy, Office of Basic Energy Sciences under Award DE-FG02-10ER46783.
Diebold, Ulrike; Li, Shao-Chun; Wang, Jian-Guo; Jacobson, Peter; Gong, Xue-Qing; Selloni, Annabella
2009-03-01
Adsorbate-induced band gap states in semiconductors are of particular interest due to the potential of increased light absorption and photoreactivity. A combined theoretical (DFT) and experimental (STM, photoemission) study of the molecular-scale factors involved in the formation of gap states in TiO2 is presented. Using the organic catechol on rutile TiO2(110) as a model system it is found that the bonding geometry strongly affects the molecular electronic structure. At saturation catechol forms an ordered 4 x 1 overlayer. This structure is attributed to catechol adsorbed on rows of surface Ti atoms with the molecular plane tilted from the surface normal by about ±27 in an alternating fashion. In the lowest-energy structure one of the two terminal OH groups at each catechol dissociates and the O binds to a surface Ti atom in a monodentate configuration, while the other OH group forms a H-bond to the next catechol neighbor. Through proton exchange with the surface this structure transforms into one where both OH groups dissociate and the catechol is bound to two surface Ti in a bidentate configuration. Only bidendate catechol introduces states in the band gap of TiO2.
Computer-based analysis of cardiac state using entropies, recurrence plots and Poincare geometry.
Chua, K C; Chandran, V; Acharya, U R; Lim, C M
2008-01-01
Heart rate variability refers to the regulation of the sinoatrial node, the natural pacemaker of the heart by the sympathetic and parasympathetic branches of the autonomic nervous system. Heart rate variability is important because it provides a window to observe the heart's ability to respond to normal regulatory impulses that affect its rhythm. A computer-based intelligent system for analysis of cardiac states is very useful in diagnostics and disease management. Parameters are extracted from the heart rate signals and analysed using computers for diagnostics. This paper describes the analysis of normal and seven types of cardiac abnormal signals using approximate entropy (ApEn), sample entropy (SampEn), recurrence plots and Poincare plot patterns. Ranges of these parameters for various cardiac abnormalities are presented with an accuracy of more than 95%. Among the two entropies, ApEn showed better performance for all the cardiac abnormalities. Typical Poincare and recurrence plots are shown for various cardiac abnormalities.
Lackner, Klaus S.; Zweig, George
1987-09-01
The arguments presented in the Comment by Liebman and Huheey are shown to be incorrect. The operational equivalence of Mulliken ground-state electronegativities and Pauling electronegativities is demonstrated for neutral atoms. It is shown that ground-state electronegativities and valence-state electronegativities for both neutral atoms and ions are also operationally equivalent. A single electronegativity scale based on Mulliken ground-state electronegativities may therefore be used for neutral atoms, ions, and fractionally charged atoms, as originally implied in the paper by Lackner and Zweig.
Directory of Open Access Journals (Sweden)
Shozo Tsunekawa
2003-01-01
Full Text Available The microwave spectrum of methyl formate has been observed in the 7-200 GHz region, and new 437 lines have been assigned to the first excited A torsional substate. Both excited state lines and ground state lines reported previously were analyzed simultaneously on the basis of an internal axis method Hamiltonian. A total of 3514 lines were fitted to a 10th-order reduced Hamiltonian model involving 67 molecular parameters to a 1s standard deviation of 179 kHz.
The fine structure levels for ground states of negative ions of nitrogen and phosphorus
Directory of Open Access Journals (Sweden)
Leyla Özdemir
2013-01-01
Full Text Available The fine structure levels for negative ions (anions of nitrogen and phosphorus have been investigated using multiconfiguration Hartree-Fock method within the framework of Breit-Pauli Hamiltonian (MCHF+BP. Nitrogen and phosphorus have half-filled outer shell in ground state 1s22s22p3 4S and 1s22s22p33s23p3 4S, respectively. It has been stated in most works that the negative ion of nitrogen is instable whereas the negative ion of phosphorus is stable. The results obtained have been compared with other works.
Ground state of excitons in quantum-dot quantum-well nanoparticles:stochastic variational method
Institute of Scientific and Technical Information of China (English)
Zhang Heng; Shi Jun-Jie
2004-01-01
Within the framework of effective mass approximation, the ground state of excitons confined in spherical core-shell quantum-dot quantum-well (QDQW) nanoparticles is solved by using the stochastic variational method, in which the finite band offset and the heavy (light) hole exciton states are considered. The calculated lse-lsh transition energies for the chosen CdS/HgS/CdS QDQW samples are in good agreement with the experimental measurements. Moreover,some previous theoretical results are improved.
Analytical expressions for partial wave two-body Coulomb transition matrices at ground-state energy
Kharchenko, V. F.
2016-11-01
Leaning upon the Fock method of the stereographic projection of the three-dimensional momentum space onto the four-dimensional unit sphere the possibility of the analytical solving of the Lippmann-Schwinger integral equation for the partial wave two-body Coulomb transition matrix at the ground bound state energy has been studied. In this case new expressions for the partial p-, d- and f-wave two-body Coulomb transition matrices have been obtained in the simple analytical form. The developed approach can also be extended to determine analytically the partial wave Coulomb transition matrices at the energies of excited bound states.
Ground State Solutions for a Semilinear Elliptic Equation Involving Concave-Convex Nonlinearities
Institute of Scientific and Technical Information of China (English)
KHAZAEE KOHPAR O; KHADEMLOO S
2013-01-01
This work is devoted to the existence and multiplicity properties of the grotmd state solutions of the semilinear boundary value problem-Au=λa(x)u｜u｜q-2+b(x) u ｜u｜2*-2 in a bounded domain coupled with Dirichlet boundary condition.Here 2* is the critical Sobolev exponent,and the term ground state refers to minimizers of the corresponding energy within the set of nontrivial positive solutions.Using the Nehari manifold method we prove that one can find an interval A such that there exist at least two positive solutions of the problem for λ ∈ A.
Ground states of bilayered and extended t-J-U models
Voo, Khee-Kyun
2015-09-01
The ground states of bilayered and extended t-J-U models are investigated with renormalized mean field theory. The trial wave functions are Gutzwiller projected Hartree-Fock states, and the site double occupancies are variational parameters. It is found that a spontaneous interlayer phase separation (PS) may arise in bilayers. In electron-hole doping asymmetric systems, the propensity for PS is stronger in electron doped bands. Via a PS, superconductivity can survive to lower doping densities, and antiferromagnetism in electron doped systems may survive to higher doping densities. The result is related to the superconducting cuprates.
Sterling, N C; Bilodeau, R C; Kilcoyne, A L D; Red, E C; Phaneuf, R A; Aguilar, A
2010-01-01
Absolute photoionization cross-section measurements are reported for Se+ in the photon energy range 18.0-31.0 eV, which spans the ionization thresholds of the 4S_{3/2} ground state and the low-lying 2P_{3/2,1/2} and 2D_{5/2,3/2} metastable states. The measurements were performed using the Advanced Light Source synchrotron radiation facility. Strong photoexcitation-autoionization resonances due to 4p-->nd transitions are seen in the cross-section spectrum and identified with a quantum-defect analysis.
Ground State Transitions of Four-Electron Quantum Dots in Zero Magnetic Field
Institute of Scientific and Technical Information of China (English)
KANG Shuai; XIE Wen-Fang; LIU Yi-Ming; SHI Ting-Yun
2008-01-01
In this paper, we study four electrons confined in a parabolic quantum dot in the absence of magnetic field, by the exact diagonalization method. The ground-state electronic structures and orbital and spin angular momenta transitions as a function of the confined strength are investigated. We find that the confinement may cause accidental degeneracies between levels with different low-lying states and the inversion of the energy values. The present results are useful to understand the optical properties and internal electron-electron correlations of quantum dot materials.
Ground State and Elementary Excitations of the S=1 Kagome Heisenberg Antiferromagnet
Hida, Kazuo
2000-01-01
Low energy spectrum of the S=1 kagom\\'e Heisenberg antiferromagnet (KHAF) is studied by means of exact diagonalization and the cluster expansion. The magnitude of the energy gap of the magnetic excitation is consistent with the recent experimental observation for \\mpynn. In contrast to the $S=1/2$ KHAF, the non-magnetic excitations have finite energy gap comparable to the magnetic excitation. As a physical picture of the ground state, the hexagon singlet solid state is proposed and verified b...
Polarizabilities and tune-out wavelengths of the hyperfine ground states of $^{87,85}$Rb
Wang, Xia; Xie, Lu-You; Zhang, Deng-Hong; Dong, Chen-Zhong
2016-01-01
The static and dynamic polarizabilities, and the tune-out wavelengths of the ground state of Rb and the hyperfine ground states of $^{87, 85}$Rb have been calculated by using relativistic configuration interaction plus core polarization(RCICP) approach. It is found that the first primary tune-out wavelengths of the $ 5s_{1/2}, F=1, 2 $ states of $ ^{87}$Rb are 790.018187(193) nm and 790.032602(193) nm severally, where the calculated result for the $ 5s_{1/2}, F=2 $ state is in good agreement with the latest high-precision measurement 790.032388(32) nm [Phys. Rev. A 92, 052501 (2015)]. Similarly, the first primary tune-out wavelengths of the $ 5s_{1/2}, F=2, 3 $ states of $^{85}$Rb are 790.023515(218) nm and 790.029918(218) nm respectively. Furthermore, the tune-out wavelengths for the different magnetic sublevels $ M_{F}$ of each hyperfine level $F$ are also determined by considering the contributions of tensor polarizabilities.
Modified magnetic ground state in NiMn2O4 thin films
Energy Technology Data Exchange (ETDEWEB)
Nelson-Cheeseman, B. B.; Chopdekar, R. V.; Toney, M. F.; Arenholz, E.; Suzuki, Y.; Iwata, J.M.
2010-08-03
We demonstrate the stabilization of a magnetic ground state in epitaxial NiMn2O4 (NMO) thin films not observed in their bulk counterpart. Bulk NMO exhibits a magnetic transition from a paramagnetic phase to a collinear ferrimagnetic moment configuration below 110 K and to a canted moment configuration below 70 K. By contrast, as-grown NMO films exhibit a single magnetic transition at 60 K and annealed films exhibit the magnetic behavior found in bulk. Cation inversion and epitaxial strain are ruled out as possible causes for the new magnetic ground state in the as-grown films. However, a decrease in the octahedral Mn{sup 4+}:Mn{sup 3+} concentration is observed and likely disrupts the double exchange that produces the magnetic state at intermediate temperatures. X-ray magnetic circular dichroism and bulk magnetometry indicate a canted ferrimagnetic state in all samples at low temperature. Together these results suggest that the collinear ferrimagnetic state observed in bulk NMO at intermediate temperatures is suppressed in the as grown NMO thin films due to a decrease in octahedral Mn{sup 4+} while the canted moment ferrimagnetic ordering is preserved below 60 K.
Modified Magnetic Ground State in Nimn (2) O (4) Thin Films
Energy Technology Data Exchange (ETDEWEB)
Nelson-Cheeseman, B.B.; Chopdekar, R.V.; Iwata, J.M.; Toney, M.F.; Arenholz, E.; Suzuki, Y.; /SLAC
2012-08-23
The authors demonstrate the stabilization of a magnetic ground state in epitaxial NiMn{sub 2}O{sub 4} (NMO) thin films not observed in their bulk counterpart. Bulk NMO exhibits a magnetic transition from a paramagnetic phase to a collinear ferrimagnetic moment configuration below 110 K and to a canted moment configuration below 70 K. By contrast, as-grown NMO films exhibit a single magnetic transition at 60 K and annealed films exhibit the magnetic behavior found in bulk. Cation inversion and epitaxial strain are ruled out as possible causes for the new magnetic ground state in the as-grown films. However, a decrease in the octahedral Mn{sup 4+}:Mn{sup 3+} concentration is observed and likely disrupts the double exchange that produces the magnetic state at intermediate temperatures. X-ray magnetic circular dichroism and bulk magnetometry indicate a canted ferrimagnetic state in all samples at low T. Together these results suggest that the collinear ferrimagnetic state observed in bulk NMO at intermediate temperatures is suppressed in the as grown NMO thin films due to a decrease in octahedral Mn{sup 4+}, while the canted moment ferrimagnetic ordering is preserved below 60 K.
Optical cooling of AlH+ to the rotational ground state
Lien, Chien-Yu; Seck, Christopher; Odom, Brian
2014-05-01
We demonstrate cooling of the rotational degree of freedom of trapped diatomic molecular ions to the rotational ground state. The molecule of interested, AlH+, is co-trapped and sympathetically cooled with Ba+ to milliKelvin temperatures in its translational degree of freedom. The nearly diagonal Franck-Condon-Factors between the electronic X and A states of AlH+ create semi-closed cycling transitions between the vibrational ground states of X and A states. A spectrally filtered femtosecond laser is used to optically pump the population to the two lowest rotational levels, with opposite parities, in as fast as 100 μs via driving the A-X transition. In addition, a cooling scheme relying on vibrational relaxation brings the population to the N = 0 positive-parity level in as fast as 100 ms. The population distribution among the rotational levels is detected by resonance-enhanced multiphoton dissociation (REMPD) and time-of-flight mass-spectrometry (TOFMS). Although the current two-photon state readout scheme is destructive, a scheme of single-molecule fluorescence detection is also considered.
Laboratory rotational ground state transitions of NH$_3$D$^+$ and CF$^+$
Stoffels, Alexander; Schlemmer, Stephan; Brünken, Sandra
2016-01-01
Aims. This paper reports accurate laboratory frequencies of the rotational ground state transitions of two astronomically relevant molecular ions, NH3D+ and CF+. Methods. Spectra in the millimeter-wave band were recorded by the method of rotational state-selective attachment of He-atoms to the molecular ions stored and cooled in a cryogenic ion trap held at 4 K. The lowest rotational transition in the A state (ortho state) of NH$_3$D$^+$ ($J_K = 1_0 - 0_0$), and the two hyperfine components of the ground state transition of CF$^+$($J = 1 - 0$) were measured with a relative precision better than $10^{-7}$. Results. For both target ions the experimental transition frequencies agree with recent observations of the same lines in different astronomical environments. In the case of NH$_3$D$^+$ the high-accuracy laboratory measurements lend support to its tentative identification in the interstellar medium. For CF$^+$ the experimentally determined hyperfine splitting confirms previous quantum-chemical calculations a...
Ground-Water Recharge in the Arid and Semiarid Southwestern United States
Stonestrom, David A.; Constantz, Jim; Ferre, Ty P.A.; Leake, Stanley A.
2007-01-01
Ground-water recharge in the arid and semiarid southwestern United States results from the complex interplay of climate, geology, and vegetation across widely ranging spatial and temporal scales. Present-day recharge tends to be narrowly focused in time and space. Widespread water-table declines accompanied agricultural development during the twentieth century, demonstrating that sustainable ground-water supplies are not guaranteed when part of the extracted resource represents paleorecharge. Climatic controls on ground-water recharge range from seasonal cycles of summer monsoonal and winter frontal storms to multimillennial cycles of glacial and interglacial periods. Precipitation patterns reflect global-scale interactions among the oceans, atmosphere, and continents. Large-scale climatic influences associated with El Ni?o and Pacific Decadal Oscillations strongly, but irregularly, control weather in the study area, so that year-to-year variations in precipitation and ground-water recharge are large and difficult to predict. Proxy data indicate geologically recent periods of naturally occurring multidecadal droughts unlike any in the modern instrumental record. Any anthropogenically induced climate change will likely reduce ground-water recharge through diminished snowpack at higher elevations. Future changes in El Ni?o and monsoonal patterns, both crucial to precipitation in the study area, are highly uncertain in current models. Current land-use modifications influence ground-water recharge through vegetation, irrigation, and impermeable area. High mountain ranges bounding the study area?the San Bernadino Mountains and Sierra Nevada to the west, and the Wasatch and southern Colorado Rocky Mountains to the east?provide external geologic controls on ground-water recharge. Internal geologic controls stem from tectonic processes that led to numerous, variably connected alluvial-filled basins, exposure of extensive Paleozoic aquifers in mountainous recharge areas
Wood, Dorothy Marie
2001-12-01
An exact power series expression has been obtained for the Franck-Condon integral (FCI) in the harmonic approximation. This expression is a function of a parameter Δ where Δ --> 0 as the frequencies of vibration in the two combining electronic states approach equality. These two characteristics, that of a power series in Δ and the fact that Δ --> 0 in certain situations, permit truncation of various functions involving FCI's. Such truncation was performed for the ratio S2v'0'' /S2(v'-1) 0'' , where the S2v'v'' are the FCI's, and the subscripts, in the usual notation, denote the vibrational quantum numbers in the two different electronic states. As a result, two approximations to the S2v'0'' /S2(v'-1) 0'' ratio were obtained: a linear approximation in Δ and a quadratic expression in Δ2. Maps of the Franck-Condon integrals, FCIM's, were found to be very useful. An FCIM is a plot of S2v'0'' (DRe) versus ΔRe for various values of the parameter v'. These FCIM's facilitated a test of the linear and quadratic approximations and led to a precise specification of the ranges of a within which they are valid. They resulted in the concept of a ``Franck-Condon window''. A Franck-Condon window (FCW) is that specific region of the FCIM (i.e., the range of ΔRe) in which the gross (i.e., non-numerical, vibronic intensity) pattern of some vibronic spectrum is represented. The vibrational intensity distributions in 60 different electronic transitions were subjected to Franck-Condon analysis using (i)the linear approximation, (ii)the quadratic approximation, (iii)the FCW approach, and (iv)the best fit to the FCIM. It was found that method (ii), (iii) & (iv) provided excellent agreement with experiment whereas method (i) produced mixed results. The analysis had some incidental benefits: it caused a reassignment of one vibronic spectrum and permitted a choice between two proposed alternative assignments for another vibronic spectrum.
Drews, Björn; Jachymski, Krzysztof; Idziaszek, Zbigniew; Denschlag, Johannes Hecker
2016-01-01
Exploring inelastic and reactive collisions on the quantum level is a main goal of the developing field of ultracold chemistry. We present first experimental studies of inelastic collisions of metastable ultracold triplet molecules in the vibrational ground state. The measurements are performed with nonpolar Rb$_2$ dimers which are prepared in precisely-defined quantum states and trapped in an array of quasi-1D potential tubes. We investigate collisions of molecules in the lowest triplet energy level where any inelastic process requires a relaxation to the singlet state. These are compared to two sets of collision experiments, carried out either with triplet molecules that have two quanta of rotational angular momentum or with vibrationally highly excited Feshbach molecules. We find no evidence for suppression of the inelastic collisions due to the necessary spin-flip, shedding light on this so far unsettled issue. For each of the molecular states studied here, we extract the decay rate constant and compare t...
2010-04-01
... of Department of State press building passes. 9b.6 Section 9b.6 Foreign Relations DEPARTMENT OF STATE GENERAL REGULATIONS GOVERNING DEPARTMENT OF STATE PRESS BUILDING PASSES § 9b.6 Grounds for denial, revocation, or non-renewal of Department of State press building passes. In consultation with the Bureau...
Directory of Open Access Journals (Sweden)
Y. Sajeev
2015-08-01
Full Text Available The equation-of-motion coupled cluster (EOMCC method based on the excited state Hartree-Fock (ESHF solutions is shown to be appropriate for computing the entire ground state potential energy curves of strongly correlated higher-order bonds. The new approach is best illustrated for the homolytic dissociation of higher-order bonds in molecules. The required multireference character of the true ground state wavefunction is introduced through the linear excitation operator of the EOMCC method. Even at the singles and doubles level of cluster excitation truncation, the nonparallelity error of the ground state potential energy curve from the ESHF based EOMCC method is small.
van den Broek, P.M.
1984-01-01
The aim of this paper is to give a detailed exposition of the relation between the geometry of twistor space and the geometry of Minkowski space. The paper has a didactical purpose; no use has been made of differential geometry and cohomology.
Ran, Shi-Ju
2016-05-01
In this work, a simple and fundamental numeric scheme dubbed as ab initio optimization principle (AOP) is proposed for the ground states of translational invariant strongly correlated quantum lattice models. The idea is to transform a nondeterministic-polynomial-hard ground-state simulation with infinite degrees of freedom into a single optimization problem of a local function with finite number of physical and ancillary degrees of freedom. This work contributes mainly in the following aspects: (1) AOP provides a simple and efficient scheme to simulate the ground state by solving a local optimization problem. Its solution contains two kinds of boundary states, one of which play the role of the entanglement bath that mimics the interactions between a supercell and the infinite environment, and the other gives the ground state in a tensor network (TN) form. (2) In the sense of TN, a novel decomposition named as tensor ring decomposition (TRD) is proposed to implement AOP. Instead of following the contraction-truncation scheme used by many existing TN-based algorithms, TRD solves the contraction of a uniform TN in an opposite way by encoding the contraction in a set of self-consistent equations that automatically reconstruct the whole TN, making the simulation simple and unified; (3) AOP inherits and develops the ideas of different well-established methods, including the density matrix renormalization group (DMRG), infinite time-evolving block decimation (iTEBD), network contractor dynamics, density matrix embedding theory, etc., providing a unified perspective that is previously missing in this fields. (4) AOP as well as TRD give novel implications to existing TN-based algorithms: A modified iTEBD is suggested and the two-dimensional (2D) AOP is argued to be an intrinsic 2D extension of DMRG that is based on infinite projected entangled pair state. This paper is focused on one-dimensional quantum models to present AOP. The benchmark is given on a transverse Ising
Millimetre-wave spectroscopy of HC{sub 4}Cl in ground and excited vibrational states
Energy Technology Data Exchange (ETDEWEB)
Bizzocchi, Luca [Dipartimento di Chimica ' G. Ciamician' , Universita di Bologna, via F. Selmi 2, 40126 Bologna (Italy)], E-mail: luca.bizzocchi@unibo.it; Degli Esposti, Claudio [Dipartimento di Chimica ' G. Ciamician' , Universita di Bologna, via F. Selmi 2, 40126 Bologna (Italy)], E-mail: claudio.degliesposti@unibo.it
2008-05-04
The semi-stable HC{sub 4}Cl molecule has been detected in the pyrolysis products of propyne and carbon tetrachloride mixtures. The rotational spectrum of the most abundant isotopologue HC{sub 4}{sup 35}Cl has been investigated in the millimetre- and sub-millimetre-wave regions for the ground and 12 vibrationally excited states which approximately lie below 630 cm{sup -1}, namely ({nu}{sub 5}{nu}{sub 6}{nu}{sub 7}{nu}{sub 8}{nu}{sub 9})=(10000), (01000), (00100), (00010), (00001), (00020), (00002), (00003), (00004), (00101), (00011) and (00012). Transitions up to J=151 <- 150 were measured for the ground state, allowing for a precise evaluation of the quartic and sextic centrifugal distortion constants D and H. The l-type resonances between the different sublevels of the bending states and the anharmonic resonance which couples the states {nu}{sub 5}=1, {nu}{sub 8}=2 and {nu}{sub 9}=4 have been taken into account in the analysis of the spectra, which yielded precise determinations of the x{sub L(99)}, x{sub L(88)}, x{sub L(89)} and x{sub L(79)} anharmonicity constants and of the {phi}{sub 588} normal coordinate cubic force constant. Extensive measurements have also been performed for the HC{sub 4}{sup 37}Cl isotopologue.
Dynamics of a Ground-State Cooled Ion Colliding with Ultracold Atoms
Meir, Ziv; Sikorsky, Tomas; Ben-shlomi, Ruti; Akerman, Nitzan; Dallal, Yehonatan; Ozeri, Roee
2016-12-01
Ultracold atom-ion mixtures are gaining increasing interest due to their potential applications in ultracold and state-controlled chemistry, quantum computing, and many-body physics. Here, we studied the dynamics of a single ground-state cooled ion during few, to many, Langevin (spiraling) collisions with ultracold atoms. We measured the ion's energy distribution and observed a clear deviation from the Maxwell-Boltzmann distribution, characterized by an exponential tail, to a power-law distribution best described by a Tsallis function. Unlike previous experiments, the energy scale of atom-ion interactions is not determined by either the atomic cloud temperature or the ion's trap residual excess-micromotion energy. Instead, it is determined by the force the atom exerts on the ion during a collision which is then amplified by the trap dynamics. This effect is intrinsic to ion Paul traps and sets the lower bound of atom-ion steady-state interaction energy in these systems. Despite the fact that our system is eventually driven out of the ultracold regime, we are capable of studying quantum effects by limiting the interaction to the first collision when the ion is initialized in the ground state of the trap.
Wilke, Josefin; Wilke, Martin; Meerts, W Leo; Schmitt, Michael
2016-01-28
The dipole moments of the ground and lowest electronically excited singlet state of 5-methoxyindole have been determined by means of optical Stark spectroscopy in a molecular beam. The resulting spectra arise from a superposition of different field configurations, one with the static electric field almost parallel to the polarization of the exciting laser radiation, the other nearly perpendicular. Each field configuration leads to different intensities in the rovibronic spectrum. With an automated evolutionary algorithm approach, the spectra can be fit and the ratio of both field configurations can be determined. A simultaneous fit of two spectra with both field configurations improved the precision of the dipole moment determination by a factor of two. We find a reduction of the absolute dipole moment from 1.59(3) D to 1.14(6) D upon electronic excitation to the lowest electronically excited singlet state. At the same time, the dipole moment orientation rotates by 54(∘) showing the importance of the determination of the dipole moment components. The dipole moment in the electronic ground state can approximately be obtained from a vector addition of the indole and the methoxy group dipole moments. However, in the electronically excited state, vector addition completely fails to describe the observed dipole moment. Several reasons for this behavior are discussed.
Gravity Monitoring of Ground-Water Storage Change in the Southwestern United States
Winester, D.; Pool, D. R.; Schmerge, D. L.; Hoffmann, J. P.; Keller, G. R.
2004-12-01
Repeat measurements of absolute gravity have been made since 1998 to estimate changes in ground-water mass as part of ground-water budget estimates in arid and semiarid regions of the Southwestern United States. The absolute acceleration of gravity is measured twice each year at 16 stations to an accuracy of about plus or minus 2 microGal, or about 5 cm of water. Observations are normally done for the purpose of providing gravity control for relative gravity surveys of networks of stations across wider areas. Other data incorporated into the ground-water budget estimates include precipitation, water levels, moisture content in the unsaturated zone, surface water runoff, and ellipsoid heights using the Global Positioning System (GPS). Gravity and water-level changes are correlated for stations measured in the Basin and Range Physiographic Province near Tucson, Phoenix, Casa Grande, and Sierra Vista, Arizona. Decreasing gravity and water levels in the Tucson area since the summer of 1998 are likely related to predominant drought conditions and decreases in ground-water storage following above average winter precipitation and recharge during the El Nino of 1998. Increases in gravity at stations in the upper and middle Verde Valley Watershed in central Arizona since the fall of 2000 do not correlate well with declining streamflows and water levels and may be caused by temporary increases in soil moisture following wet winters. There have been no significant observed gravity changes at two stations in the El Paso, Texas, area since the initial observations during the summer of 2003, even though ground-water pumping in the area has been heavy.
Prevalence of Campylobacter species in ground water in Sokoto, Sokoto state, Nigeria
Directory of Open Access Journals (Sweden)
Agatha N. Ugboma
2013-12-01
Full Text Available Aim: The present study was conducted to determine the presence and prevalence of Campylobacter species in ground water in Sokoto, Sokoto State. Materials and Methods: The prevalence of Campylobacter species was determined by collecting a total of 74 water samples from wells in Sokoto over a period of four months from May to August 2011 and analyzed using cultural isolation techniques and biochemical characterization. Results: Totally 39 (52.70% water samples were Campylobacter positive. The species identified were Campylobacter jejuni 23 (58.97%, Campylobacter coli 11 (28.21% and Campylobacter hyointestinalis 5 (12.82%. Conclusion: Based on this study, the isolation of Campylobacter species from ground water (wells in this study is of serious public health importance as untreated water has been implicated as the cause of sporadic infections and outbreaks of Campylobacteriosis worldwide. [Vet World 2013; 6(6.000: 285-287
Theoretical study of the ground-state structures and properties of niobium hydrides under pressure
Gao, Guoying; Hoffmann, Roald; Ashcroft, N. W.; Liu, Hanyu; Bergara, Aitor; Ma, Yanming
2013-11-01
As part of a search for enhanced superconductivity, we explore theoretically the ground-state structures and properties of some hydrides of niobium over a range of pressures and particularly those with significant hydrogen content. A primary motivation originates with the observation that under normal conditions niobium is the element with the highest superconducting transition temperature (Tc), and moreover some of its compounds are metals again with very high Tc's. Accordingly, combinations of niobium with hydrogen, with its high dynamic energy scale, are also of considerable interest. This is reinforced further by the suggestion that close to its insulator-metal transition, hydrogen may be induced to enter the metallic state somewhat prematurely by the addition of a relatively small concentration of a suitable transition metal. Here, the methods used correctly reproduce some ground-state structures of niobium hydrides at even higher concentrations of niobium. Interestingly, the particular stoichiometries represented by NbH4 and NbH6 are stabilized at fairly low pressures when proton zero-point energies are included. While no paired H2 units are found in any of the hydrides we have studied up to 400 GPa, we do find complex and interesting networks of hydrogens around the niobiums in high-pressure NbH6. The Nb-Nb separations in NbHn are consistently larger than those found in Nb metal at the respective pressures. The structures found in the ground states of the high hydrides, many of them metallic, suggest that the coordination number of hydrogens around each niobium atom grows approximately as 4n in NbHn (n = 1-4), and is as high as 20 in NbH6. NbH4 is found to be a plausible candidate to become a superconductor at high pressure, with an estimated Tc ˜ 38 K at 300 GPa.
An exploration of electronic structure and nuclear dynamics in tropolone. I. The X~ 1A1 ground state
Burns, Lori A.; Murdock, Daniel; Vaccaro, Patrick H.
2006-05-01
The ground electronic state (X˜A11) of tropolone has been examined theoretically by exploiting extensive sets of basis functions [e.g., 6-311++G(d,p) and aug-cc-pVDZ] in conjunction with the high levels of electron correlation made possible by density functional (DFT/B3LYP), Møller-Plesset perturbation (MP2), and coupled-cluster [CCSD and CCSD(T)] methods. Unconstrained MP2 and CCSD optimization procedures performed with the reference 6-311++G(d,p) basis predict a slightly nonplanar equilibrium structure characterized by a small barrier to skeletal inversion (⩽10cm-1 magnitude). Complementary harmonic frequency analyses have shown this nonplanarity to be a computational artifact arising from adversely tuned carbon d-orbital exponents embodied in the standard definitions of several Pople-type basis sets. Correlation-consistent bases such as Dunning's aug-cc-pVDZ are less susceptible to these effects and were employed to confirm that the X˜A11 hypersurface supports a rigorously planar global minimum. The fully optimized geometries and vibrational force fields obtained by applying potent coupled-cluster schemes to the relaxed-equilibrium (Cs) and transition-state (C2v) conformers of tropolone afford a trenchant glimpse of the key features that mediate intramolecular hydron exchange in this model system. By incorporating perturbative triples corrections at the substantial CCSD(T) level of theory, an interoxygen distance of rO ⋯O=2.528Å was determined for the minimum-energy configuration, with the accompanying proton-transfer reaction being hindered by a barrier of 2557.0cm-1 height. The potential energy landscape in tropolone, as well as the nature of the attendant hydron migration process, is discussed within the framework of the encompassing G4 molecular symmetry group.
Mustard, Thomas J L; Wender, Paul A; Cheong, Paul Ha-Yeon
2015-03-06
The origins of differential catalytic reactivities of four Rh(I) catalysts and their derivatives in the (5 + 2) cycloaddition reaction were elucidated using density functional theory. Computed free energy spans are in excellent agreement with known experimental rates. For every catalyst, the substrate geometries in the transition state remained constant (Catalytic efficiency is shown to be a function of how well the catalyst accommodates the substrate transition state geometry and electronics. This shows that the induced fit model for explaining biological catalysis may be relevant to transition metal catalysis. This could serve as a general model for understanding the origins of efficiencies of catalytic reactions.
Ground-state phase diagram for a system of interacting, D(D{sub 3}) non-Abelian anyons
Energy Technology Data Exchange (ETDEWEB)
Finch, P.E., E-mail: peter.finch@itp.uni-hannover.d [Institut fuer Theoretische Physik, Leibniz Universitaet Hannover, Appelstrasse 2, 30167 Hannover (Germany); Frahm, H. [Institut fuer Theoretische Physik, Leibniz Universitaet Hannover, Appelstrasse 2, 30167 Hannover (Germany); Links, J. [Centre for Mathematical Physics, School of Mathematics and Physics, The University of Queensland, 4072 (Australia)
2011-03-01
We study an exactly solvable model of D(D{sub 3}) non-Abelian anyons on a one-dimensional lattice with a free coupling parameter in the Hamiltonian. For certain values of the coupling parameter level crossings occur, which divide the ground-state phase diagram into four regions. We obtain explicit expressions for the ground-state energy in each phase, for both closed and open chain boundary conditions. For the closed chain case we show that chiral phases occur which are characterised by non-zero ground-state momentum.
Institute of Scientific and Technical Information of China (English)
LIU Jia; XIAO Jing-Ling
2006-01-01
We study theoretically the ground state energy of a polaron near the interface of a polar-polar semiconductor by considering the Rashba spin-orbit (SO) coupling with the Lee-Low-Pines intermediate coupling method. Our numerical results show that the Rashba SO interaction originating from the inversion asymmetry in the heterostructure splits the ground state energy of the polaron. The electron arealdensity and vector dependence of the ratio of the SO interaction to the total ground state energy or other energy composition are obvious. One can see that even without any external magnetic field, the ground state energy can be split by the Rashba SO interaction, and this split is not a single but a complex one. Since the presents of the phonons, whose energy gives negative contribution to the polaron's,the spin-splitting states of the polaron are more stable than electron's.
The ground and excited state electron affinities of cytosine and trans-azobenzene
Chen, Edward C. M.; Herder, Charles; Chen, Edward S.
2007-06-01
The electron capture detector, reduction potential, electron transfer and photon methods of determining electron affinities are compared. The adiabatic electron affinities are (in eV): t-azobenzene(O 2), 1.578(5); t-azobenzene, 1.378(5); cytosine, 1.043(5) from anion photoelectron spectra. The largest or ground state value for trans-azobenzene and an excited state electron affinity for cytosine, 0.70 eV are also determined by reduction potentials. Other excited state energies are (in eV): t-azobenzene, 0.328(5), 0.589(5), 0.690(5), 0.768(5), 0.954(5), 1.038(5), 1.150(5), 1.275(5) and cytosine, 0.089(5), 0.098(5), 0.198(5), 0.235(5). The cytosine values are consistent with electron transport and radiation damage and repair in DNA.
Time delay anisotropy in photoelectron emission from the isotropic ground state of helium
Heuser, Sebastian; Cirelli, Claudio; Sabbar, Mazyar; Boge, Robert; Lucchini, Matteo; Gallmann, Lukas; Ivanov, Igor; Kheifets, Anatoli S; Dahlström, J Marcus; Lindroth, Eva; Argenti, Luca; Martín, Fernando; Keller, Ursula
2015-01-01
Time delays of electrons emitted from an isotropic initial state and leaving behind an isotropic ion are assumed to be angle-independent. Using an interferometric method involving XUV attosecond pulse trains and an IR probe field in combination with a detection scheme, which allows for full 3D momentum resolution, we show that time delays between electrons liberated from the $1s^{2}$ spherically symmetric ground state of He depend on the emission direction of the electrons with respect to the linear polarization axis of the ionizing XUV light. Such time delays can exhibit values as large as 60 attoseconds. With the help of refined theoretical models we can attribute the observed anisotropy to the interplay between different final quantum states, which arise naturally when two photons are involved in the photoionization process. Since most measurement techniques tracing attosecond electron dynamics have involved at least two photons so far, this is a general, significant, and initially unexpected effect that m...
Renes, Joseph M; Brennen, Gavin K; Bartlett, Stephen D
2011-01-01
While solid-state devices offer naturally reliable hardware for modern classical computers, thus far quantum information processors resemble vacuum tube computers in being neither reliable nor scalable. Strongly correlated many body states stabilized in topologically ordered matter offer the possibility of naturally fault tolerant computing, but are both challenging to engineer and coherently control and cannot be easily adapted to different physical platforms. We propose an architecture which achieves some of the robustness properties of topological models but with a drastically simpler construction. Quantum information is stored in the degenerate ground states of spin-1 chains exhibiting symmetry-protected topological order (SPTO), while quantum gates are performed by adiabatic non-Abelian holonomies using only single-site fields and nearest-neighbor couplings. Gate operations respect the SPTO symmetry, inheriting some protection from noise and disorder from the SPTO robustness to local perturbation. A pote...
Unconventional magnetic ground state in Yb2Ti2O7
D'Ortenzio, R. M.; Dabkowska, H. A.; Dunsiger, S. R.; Gaulin, B. D.; Gingras, M. J. P.; Goko, T.; Kycia, J. B.; Liu, L.; Medina, T.; Munsie, T. J.; Pomaranski, D.; Ross, K. A.; Uemura, Y. J.; Williams, T. J.; Luke, G. M.
2013-10-01
We report low-temperature specific heat and positive muon spin relaxation/rotation (μSR) measurements on both polycrystalline and single-crystal samples of the pyrochlore magnet Yb2Ti2O7. This material is believed to possess a spin Hamiltonian able to support a quantum spin ice (QSI) ground state. Yb2Ti2O7 displays sample variation in its low-temperature heat capacity and, while our two samples exhibit extremes of this variation, our μSR measurements indicate a similar disordered low-temperature state down to 16 mK in both. We report little temperature dependence to the muon spin relaxation and no evidence for ferromagnetic order, in contrast to reports by Chang [Nat. Comm.2041-172310.1038/ncomms1989 3, 992 (2012)] and Yasui [J. Phys. Soc. Japan. 72, 11 (2003)]. Transverse field (TF) μSR measurements show changes in the temperature dependence of the muon Knight shift that coincide with heat capacity anomalies, which, incidentally, prove that the implanted muons are not diffusing in Yb2Ti2O7. From these results, we are led to propose that Yb2Ti2O7 enters an unconventional ground state below Tc˜265 mK. As found for all the current leading experimental candidates for a quantum spin liquid state, the precise nature of the state below Tc in Yb2Ti2O7 remains unknown and, at this time, defined by what is not as opposed to what it is: lacking simple periodic long-range order or a frozen spin glass state.
Huang, Wei; Xu, Wen-Hua; Su, Jing; Schwarz, W H E; Li, Jun
2013-12-16
In neutral chemical compounds, the highest known oxidation state of all elements in the Periodic Table is +VIII. While PuO4 is viewed as an exotic Pu(+VIII) complex, we have shown here that no stable electronic homologue of octavalent RuO4 and OsO4 exists for PuO4, even though Pu has the same number of eight valence electrons as Ru and Os. Using quantum chemical approaches at the levels of quasi-relativistic DFT, MP2, CCSD(T), and CASPT2, we find the ground state of PuO4 as a quintet (5)C2v-(PuO2)(+)(O2)(-) complex with the leading valence configuration of an (f(3))plutonyl(V) unit, loosely coupled to a superoxido (π*(3))O2(-) ligand. This stable isomer is likely detectable as a transient species, while the previously suggested planar (1)D4h-Pu(VIII)O4 isomer is only metastable. Through electronic structure analyses, the bonding and the oxidation states are explained and rationalized. We have predicted the characteristics of the electronic and vibrational spectra to assist future experimental identification of (PuO2)(+)(O2)(-) by IR, UV-vis, and ionization spectroscopy.
Ground- and excited-state structural orientation of 2-(2`-hydroxyphenyl)benzazoles in cyclodextrins
Energy Technology Data Exchange (ETDEWEB)
Roberts, E.L.; Dey, J.; Warner, I.M. [Louisiana State Univ., Baton Rouge, LA (United States)
1996-12-12
The effects of {alpha}-, {beta}-, {gamma}-, and 2,6-di-O-methyl-{beta}-cyclodextrins (CDs) on the ground- and excited-state properties of 2-(2`-hydroxyphenyl)benzoxazole, 2-(2`-hydroxyphenyl)benzothiazole, and 2-(2`-hydroxyphenyl)benzimidazole in aqueous media are investigated. Steady-state fluorescence measurements are used to characterize the interaction of CDs with these azoles. Absorbance measurements indicate increased solubility of the azoles in aqueous solutions of CDs. Measurements of acidity constants (pK{sub a}) and data from induced circular dichroism indicate increased ground- and excited-state acidities of the phenolic protons of the molecules in the presence of CDs and axial orientation of the molecules within the CD cavity, respectively. The data further suggest a planar structure for HBO and a twisted confirmation for both HBT and HBI. The association constants of the inclusion complexes have also been estimated. These studies are further supplemented by comparative spectroscopic studies of 2-(2`-methoxyphenyl)benzothiazole in aqueous solutions of CDs. On the basis of the spectral data acquired, it is believed that the HBA molecules exist as zwitterionic tautomers in the presence of CDs. 35 refs., 6 figs., 2 tabs.
Covariant energy density functionals: nuclear matter constraints and global ground state properties
Afanasjev, A V
2016-01-01
The correlations between global description of the ground state properties (binding energies, charge radii) and nuclear matter properties of the state-of-the-art covariant energy density functionals have been studied. It was concluded that the strict enforcement of the constraints on the nuclear matter properties (NMP) defined in Ref.\\ \\cite{RMF-nm} will not necessary lead to the functionals with good description of the binding energies and other ground and excited state properties. In addition, it will not substantially reduce the uncertainties in the predictions of the binding energies in neutron-rich systems. It turns out that the functionals, which come close to satisfying these NMP constraints, have some problems in the description of existing data. On the other hand, these problems are either absent or much smaller in the functionals which are carefully fitted to finite nuclei but which violate some NMP constraints. This is a consequence of the fact that the properties of finite nuclei are defined not o...
Thermodynamic framework for the ground state of a simple quantum system
Souza, Andre M. C.; Nobre, Fernando D.
2017-01-01
The ground state of a two-level system (associated with probabilities p and 1 -p , respectively) defined by a general Hamiltonian H ̂=Ĥ0+λ V ̂ is studied. The simple case characterized by λ =0 , whose Hamiltonian Ĥ0 is represented by a diagonal matrix, is well established and solvable within Boltzmann-Gibbs statistical mechanics; in particular, it follows the third law of thermodynamics, presenting zero entropy (SBG=0 ) at zero temperature (T =0 ). Herein it is shown that the introduction of a perturbation λ V ̂ (λ >0 ) in the Hamiltonian may lead to a nontrivial ground state, characterized by an entropy S [p ] (with S [p ] ≠SBG[p ] ), if the Hermitian operator V ̂ is represented by a 2 ×2 matrix, defined by nonzero off-diagonal elements V12=V21=-z , where z is a real positive number. Hence, this new term in the Hamiltonian, presenting V12≠0 , may produce physically significant changes in the ground state, and especially, it allows for the introduction of an effective temperature θ (θ ∝λ z ), which is shown to be a parameter conjugated to the entropy S . Based on this, one introduces an infinitesimal heatlike quantity, δ Q =θ d S , leading to a consistent thermodynamic framework, and by proposing an infinitesimal form for the first law, a Carnot cycle and thermodynamic potentials are obtained. All results found are very similar to those of usual thermodynamics, through the identification T ↔θ , and particularly the form for the efficiency of the proposed Carnot Cycle. Moreover, S also follows a behavior typical of a third law, i.e., S →0 , when θ →0 .
Institute of Scientific and Technical Information of China (English)
ZHENG Gong-Ping; QIN Shuai-Feng; WANG Shou-Yang; JIAN Wen-Tian
2013-01-01
The ground states of the ultracold spin-1 atoms trapped in a deep one-dimensional double-well optical superlattice in a weak magnetic field are obtained.It is shown that the ground-state diagrams of the reduced doublewell model are remarkably different for the antiferromagnetic and ferromagnetic condensates.The transition between the singlet state and nematic state is observed for the antiferromagnetic interaction atoms,which can be realized by modulating the tunneling parameter or the quadratic Zeeman energy.An experiment to distinguish the different spin states is suggested.
Spin-Exchange Collisions of the Ground State of Cs Atoms in a High Magnetic Field
Institute of Scientific and Technical Information of China (English)
FU Li-Ping; LUO Jun; ZENG Xi-Zhi
2000-01-01
Cs atoms were optically pumped with a Ti:sapphire laser in a magnetic field of 1.516 T. Steady absorption spectra and populations of Zeeman sublevels of the ground state of Cs in N2 gas at various pressures (5, 40, and 80 Torr)were obtained. The results show that in a high magnetic field, the combined electron-nuclear spin transition(flip-flop transition), which is mainly induced by the collision modification δa( J.I)of hyperfine interaction, is an important relaxation mechanism at high buffer-gas pressures.
Phenomenological description of ground state bands for doubly even plutonium-isotopes
Alsoraya, A M
2002-01-01
The energy levels of the ground state bands of even-even plutonium-isotopes are studied according to the variable moment of inertia (VMI), variable moment of inertia nuclear softness (VMINS) and nuclear softness (NS) models. In general, the NS3 model leads to more reasonable results than the others. The backbending phenomena in these were described and discussed. The calculations of the transition probabilities B(E2) show that the effect of addition of each neutron pair on the deformation parameter (BETA) is very small. Furthermore, the proton and neutron effective charges are found to be e sub = 0.48 eb and e-v =0.33 eb.
Mancera, L; Takeuchi, N
2003-01-01
We have studied the structural and electronic properties of YN in rock salt (sodium chloride), caesium chloride, zinc blende and wurtzite structures using first-principles total energy calculations. Rock salt is the calculated ground state structure with a = 4.93 A, B sub 0 = 157 GPa. The experimental lattice constant is a = 4.877 A. There is an additional local minimum in the wurtzite structure with total energy 0.28 eV/unit cell higher. At high pressure (approx 138 GPa), our calculations predict a phase transformation from a NaCl to a CsCl structure.
Ground-state OH maser distributions in the Galactic Centre region
Qiao, Hai-Hua; Shen, Zhi-Qiang; Dawson, Joanne R
2016-01-01
Ground-state OH masers identified in the Southern Parkes Large-Area Survey in Hydroxyl were observed with the Australia Telescope Compact Array to obtain positions with high accuracy ($\\sim$1\\,arcsec). We classified these OH masers into evolved star OH maser sites, star formation OH maser sites, supernova remnant OH maser sites, planetary nebula OH maser sites and unknown maser sites using their accurate positions. Evolved star and star formation OH maser sites in the Galactic Centre region (between Galactic longitudes of $-5^{\\circ}$ to $+5^{\\circ}$ and Galactic latitudes of $-2^{\\circ}$ and $+2^{\\circ}$) were studied in detail to understand their distributions.
Banerjee, Jayita; Carollo, Ryan; Bellos, Michael; Eyler, Edward E; Gould, Phillip L; Stwalley, William C
2012-01-01
We report continuous direct photoassociative formation of ultracold KRb molecules in the lowest vibrational levels $(v"=0 -10)$ of the electronic ground state $(X ^1\\Sigma^+)$, starting from $^{39}$K and $^{85}$Rb atoms in a magneto-optical trap. The process exploits a newfound resonant coupling between the $2(1), v'=165$ and $4(1), v'=61$ levels, which exhibit an almost equal admixture of the uncoupled eigenstates. The production rate of the $X^1\\Sigma^+$ ($v"$=0) level is estimated to be $5\\times10^3$ molecules/sec.
Highly twisted 1,2:8,9-dibenzozethrenes: Synthesis, ground state, and physical properties
Sun, Zhe
2014-08-08
Two soluble and stable 1,2:8,9-dibenzozethrene derivatives (3a,b) are synthesized through a palladium-catalyzed cyclodimerization reaction. X-ray crystallographic analysis shows that these molecules are highly twisted owing to congestion at the cove region. Broken-symmetry DFT calculations predict that they have a singlet biradical ground state with a smaller biradical character and a large singlet-triplet energy gap; these predictions are supported by NMR and electronic absorption measurements. They have small energy gaps and exhibit farred/near-infrared absorption/emission and amphoteric redox behaviors.
The ground state of the D=11 supermembrane and matrix models on compact regions
Boulton, L; Restuccia, A
2015-01-01
We establish a general framework for the analysis of boundary value problems at zero energy of matrix models on compact regions. This allows us to prove existence and uniqueness of ground state wavefunctions for the mass operator of the D=11 regularized supermembrane theory (and therefore the N=16 supersymmetric matrix model) on a ball of finite radius. Our results rely on the structure of the associated Dirichlet form and a factorization in terms of the supersymmetric charges. They also rely on the polynomial structure of the potential and various other supersymmetric properties of the system.
Positive ground state solutions to Schrodinger-Poisson systems with a negative non-local term
Directory of Open Access Journals (Sweden)
Yan-Ping Gao
2015-04-01
Full Text Available In this article, we study the Schrodinger-Poisson system $$\\displaylines{ -\\Delta u+u-\\lambda K(x\\phi(xu=a(x|u|^{p-1}u, \\quad x\\in\\mathbb{R}^3, \\cr -\\Delta\\phi=K(xu^{2},\\quad x\\in\\mathbb{R}^3, }$$ with $p\\in(1,5$. Assume that $a:\\mathbb{R}^3\\to \\mathbb{R^{+}}$ and $K:\\mathbb{R}^3\\to \\mathbb{R^{+}}$ are nonnegative functions and satisfy suitable assumptions, but not requiring any symmetry property on them, we prove the existence of a positive ground state solution resolved by the variational methods.
1 and 2 transitions in the ground-state configuration of atomic manganese
Indian Academy of Sciences (India)
S Kabakçi; B Karaçoban Usta; L Özdemir
2015-10-01
Using the multiconfiguration Hartree–Fock approximation within the framework of the Breit–Pauli Hamiltonian (MCHF+BP) and the relativistic Hartree–Fock (HFR) approximation, we have calculated the forbidden transition (1 and 2) parameters such as transition energies, logarithmic weighted oscillator strengths and transition probabilities between the fine-structure levels in the ground-state configuration of 3d5 4s2 for atomic manganese (Mn I, Z =25). A discussion of these calculations for manganese using MCHF+BP and HFR methods is given here.
Light-cone distribution amplitudes of the ground state bottom baryons in HQET
Energy Technology Data Exchange (ETDEWEB)
Ali, A.; Wang, W. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Hambrock, C. [Technische Univ. Dortmund (Germany); Parkhomenko, A.Ya. [P.G. Demidov Yaroslavl State Univ., Yaroslavl (Russian Federation)
2012-12-15
We provide the definition of the complete set of light-cone distribution amplitudes (LCDAs) for the ground state heavy bottom baryons with the spin-parities J{sup P}=1/2{sup +} and J{sup P}=3/2{sup +} in the heavy quark limit. We present the renormalization effects on the twist-2 light-cone distribution amplitudes and use the QCD sum rules to compute the moments of twist-2, twist-3, and twist-4 LCDAs. Simple models for the heavy baryon distribution amplitudes are analyzed with account of their scale dependence.
Towards photonic quantum simulation of ground states of frustrated Heisenberg spin systems.
Ma, Xiao-song; Dakić, Borivoje; Kropatschek, Sebastian; Naylor, William; Chan, Yang-hao; Gong, Zhe-xuan; Duan, Lu-ming; Zeilinger, Anton; Walther, Philip
2014-01-07
Photonic quantum simulators are promising candidates for providing insight into other small- to medium-sized quantum systems. Recent experiments have shown that photonic quantum systems have the advantage to exploit quantum interference for the quantum simulation of the ground state of Heisenberg spin systems. Here we experimentally characterize this quantum interference at a tuneable beam splitter and further investigate the measurement-induced interactions of a simulated four-spin system by comparing the entanglement dynamics using pairwise concurrence. We also study theoretically a four-site square lattice with next-nearest neighbor interactions and a six-site checkerboard lattice, which might be in reach of current technology.
Ground State Correlations Using exp(S) Method for the ^16O Nucleus.
Mihaila, Bogdan; Heisenberg, Jochen
1998-04-01
We use the Argonne-v18 potential together with a phenomenological three-nucleon interaction to do the calculation of the mean-field single particle wave functions and the correlation operator describing the ground state of the ^16O nucleus. Our correlation operator includes the contributions from up to 4p4h terms. We present a breakdown of the contributions to the binding from the two- and the three-body interactions. The one- and the two-body densities for ^16O are presented. Effects of the center-of-mass correction on the charge density and form factor are also discussed.
Ground states for Schrodinger-Poisson systems with three growth terms
Directory of Open Access Journals (Sweden)
Hui Zhang
2014-12-01
Full Text Available In this article we study the existence and nonexistence of ground states of the Schrodinger-Poisson system $$\\displaylines{ -\\Delta u+V(xu+K(x\\phi u=Q(xu^3,\\quad x\\in \\mathbb{R}^3,\\cr -\\Delta\\phi=K(xu^2, \\quad x\\in \\mathbb{R}^3, }$$ where V, K, and Q are asymptotically periodic in the variable x. The proof is based on the the method of Nehari manifold and concentration compactness principle. In particular, we develop the method of Nehari manifold for Schrodinger-Poisson systems with three times growth.
Quantum Cohesion Oscillation of Electron Ground State in Low Temperature Laser Plasma
Zhao, Qingxun; Zhang, Ping; Dong, Lifang; Zhang, Kaixi
1996-01-01
The development of radically new technological and economically efficient methods for obtaining chemical products and for producing new materials with specific properties requires the study of physical and chemical processes proceeding at temperature of 10(exp 3) to 10(exp 4) K, temperature range of low temperature plasma. In our paper, by means of Wigner matrix of quantum statistical theory, a formula is derived for the energy of quantum coherent oscillation of electron ground state in laser plasma at low temperature. The collective behavior would be important in ion and ion-molecule reactions.
Uniqueness of non-linear ground states for fractional Laplacians in R
DEFF Research Database (Denmark)
Frank, Rupert L.; Lenzmann, Enno
2013-01-01
We prove uniqueness of ground state solutions Q = Q(|x|) ≥ 0 of the non-linear equation (−Δ)sQ+Q−Qα+1=0inR,where 0 ... recently raised by Kenig–Martel–Robbiano and we generalize (by completely different techniques) the specific uniqueness result obtained by Amick and Toland for s=12 and α = 1 in [5] for the Benjamin–Ono equation. As a technical key result in this paper, we show that the associated linearized operator L...... Benjamin–Ono (BO) and Benjamin–Bona–Mahony (BBM) water wave equations....