Electromagnetic interactions in relativistic infinite component wave equations

International Nuclear Information System (INIS)

Gerry, C.C.

1979-01-01

The electromagnetic interactions of a composite system described by relativistic infinite-component wave equations are considered. The noncompact group SO(4,2) is taken as the dynamical group of the systems, and its unitary irreducible representations, which are infinite dimensional, are used to find the energy spectra and to specify the states of the systems. First the interaction mechanism is examined in the nonrelativistic SO(4,2) formulation of the hydrogen atom as a heuristic guide. A way of making a minimal relativistic generalization of the minimal ineractions in the nonrelativistic equation for the hydrogen atom is proposed. In order to calculate the effects of the relativistic minimal interactions, a covariant perturbation theory suitable for infinite-component wave equations, which is an algebraic and relativistic version of the Rayleigh-Schroedinger perturbation theory, is developed. The electric and magnetic polarizabilities for the ground state of the hydrogen atom are calculated. The results have the correct nonrelativistic limits. Next, the relativistic cross section of photon absorption by the atom is evaluated. A relativistic expression for the cross section of light scattering corresponding to the seagull diagram is derived. The Born amplitude is combusted and the role of spacelike solutions is discussed. Finally, internal electromagnetic interactions that give rise to the fine structure splittings, the Lamb shifts and the hyperfine splittings are considered. The spin effects are introduced by extending the dynamical group

Heavy-ion interactions in relativistic mean-field models

International Nuclear Information System (INIS)

Rashdan, M.

1996-01-01

The interaction potential between spherical nuclei and the elastic scattering cross section are calculated within relativistic mean-field (linear and non-linear) models, using a generalized relativistic local density approximation. The nuclear densities are calculated self-consistently from the solution of the relativistic mean-field equations. It is found that both the linear and non-linear models predict the characteristic switching-over phenomenon of the heavy-ion nuclear potential, where the potential gets attraction with increasing energy up to some value where it reverses this behaviour. The non-linear NLC model predicts a deeper potential than the linear LW model. The elastic scattering cross section calculated within the non-linear NLC model is in better agreement with experiments than that calculated within the linear LW model. (orig.)

Convergence of configuration-interaction single-center calculations of positron-atom interactions

International Nuclear Information System (INIS)

Mitroy, J.; Bromley, M. W. J.

2006-01-01

The configuration interaction (CI) method using orbitals centered on the nucleus has recently been applied to calculate the interactions of positrons interacting with atoms. Computational investigations of the convergence properties of binding energy, phase shift, and annihilation rate with respect to the maximum angular momentum of the orbital basis for the e + Cu and PsH bound states, and the e + -H scattering system were completed. The annihilation rates converge very slowly with angular momentum, and moreover the convergence with radial basis dimension appears to be slower for high angular momentum. A number of methods of completing the partial wave sum are compared; an approach based on a ΔX J =a(J+(1/2)) -n +b(J+(1/2)) -(n+1) form [with n=4 for phase shift (or energy) and n=2 for the annihilation rate] seems to be preferred on considerations of utility and underlying physical justification

Configuration interaction calculations of positron binding to Be(3P )

International Nuclear Information System (INIS)

Bromley, M.W.J.; Mitroy, J.

2006-01-01

The configuration interaction method is applied to investigate the possibility of positron binding to the metastable beryllium (1s 2 2s2p 3 P ) state. The largest calculation obtained an estimated energy that was unstable by 0.00014 Hartree with respect to the Ps + Be + (2s) lowest dissociation channel. It is likely that positron binding to parent states with non-zero angular momentum is inhibited by centrifugal barriers

Large-scale ab initio configuration interaction calculations for light nuclei

International Nuclear Information System (INIS)

Maris, Pieter; Potter, Hugh; Vary, James P; Aktulga, H Metin; Ng, Esmond G; Yang Chao; Caprio, Mark A; Çatalyürek, Ümit V; Saule, Erik; Oryspayev, Dossay; Sosonkina, Masha; Zhou Zheng

2012-01-01

In ab-initio Configuration Interaction calculations, the nuclear wavefunction is expanded in Slater determinants of single-nucleon wavefunctions and the many-body Schrodinger equation becomes a large sparse matrix problem. The challenge is to reach numerical convergence to within quantified numerical uncertainties for physical observables using finite truncations of the infinite-dimensional basis space. We discuss strategies for constructing and solving the resulting large sparse matrix eigenvalue problems on current multicore computer architectures. Several of these strategies have been implemented in the code MFDn, a hybrid MPI/OpenMP Fortran code for ab-initio nuclear structure calculations that can scale to 100,000 cores and more. Finally, we will conclude with some recent results for 12 C including emerging collective phenomena such as rotational band structures using SRG evolved chiral N3LO interactions.

Wavefunction and energy of the 1s22sns configuration in a beryllium atom

International Nuclear Information System (INIS)

Huang Shizhong; Ma Kun; Yu Jiaming; Liu Fen

2008-01-01

A new set of trial functions for 1s 2 2sns configurations in a beryllium atom is suggested. A Mathematica program based on the variational method is developed to calculate the wavefunctions and energies of 1s 2 2sns (n = 3–6) configurations in a beryllium atom. Non-relativistic energy, polarization correction and relativistic correction which include mass correction, one-and two-body Darwin corrections, spin-spin contact interaction and orbit-orbit interaction, are calculated respectively. The results are in good agreement with experimental data. (atomic and molecular physics)

Relativistic QRPA Calculation of β-Decay Rates of r-process Nuclei

International Nuclear Information System (INIS)

Marketin, T.; Paar, N.; Niksic, T.; Vretenar, D.; Ring, P.

2009-01-01

A systematic, fully self-consistent calculation of β-decay rates is presented, based on a microscopic theoretical framework. Analysis is performed on a large number of nuclei from the valley of β stability towards the neutron drip-line. Nuclear ground state is determined using the Relativistic Hartree-Bogoliubov (RHB) model with density-dependent meson-nucleon coupling constants. Transition rates are calculated within the proton-neutron relativistic quasiparticle RPA (pn-RQRPA) using the same interaction that was used in the RHB equations.

Breit–Pauli atomic structure calculations for Fe XI

International Nuclear Information System (INIS)

Aggarwal, Sunny; Singh, Jagjit; Mohan, Man

2013-01-01

Energy levels, oscillator strengths, and transition probabilities are calculated for the lowest-lying 165 energy levels of Fe XI using configuration-interaction wavefunctions. The calculations include all the major correlation effects. Relativistic effects are included in the Breit–Pauli approximation by adding mass-correction, Darwin, and spin–orbit interaction terms to the non-relativistic Hamiltonian. For comparison with the calculated ab initio energy levels, we have also calculated the energy levels by using the fully relativistic multiconfiguration Dirac–Fock method. The calculated results are in close agreement with the National Institute of Standards and Technology compilation and other available results. New results are predicted for many of the levels belonging to the 3s3p 4 3d and 3s3p 3 3d 2 configurations, which are very important in astrophysics, relevant, for example, to the recent observations by the Hinode spacecraft. We expect that our extensive calculations will be useful to experimentalists in identifying the fine structure levels in their future work

Importance of self-consistency in relativistic continuum random-phase approximation calculations

International Nuclear Information System (INIS)

Yang Ding; Cao Ligang; Tian Yuan; Ma Zhongyu

2010-01-01

A fully consistent relativistic continuum random phase approximation (RCRPA) is constructed, where the contribution of the continuum spectrum to nuclear excitations is treated exactly by the single-particle Green's function technique. The full consistency of the calculations is achieved that the same effective Lagrangian is adopted for the ground state and the excited states. The negative energy states in the Dirac sea are also included in the single-particle Green's function in the no-sea approximation. The currents from the vector meson and photon exchanges and the Coulomb interaction in RCRPA are treated exactly. The spin-orbit interaction is included naturally in the relativistic frame. Numerical results of the RCRPA are checked with the constrained relativistic mean-field theory. We study the effects of the inconsistency, particularly the currents and Coulomb interaction in various collective multipole excitations.

Theoretical investigation of the energy spectra of the oxygen isoelectronic sequences taking into account relativistic corrections

International Nuclear Information System (INIS)

Bogdanovich, P.O.; Shadzhyuvene, S.D.; Boruta, I.I.; Rudzikas, Z.B.

1976-01-01

A method for calculating energy spectra of atoms and ions having complex electron configurations is developed which takes into account relativistic corrections of the order of magnitude of the square of the structure constant. The corrections included are caused by the dependence of the electron mass on velocity; by orbit-orbit interaction; by contact interaction and by spin-orbit interaction. The method described is realized in the form of universal algorithms and programs which are written in the Fortran 4 in the BESM-6 version. Examples are given of calculating the ground ls 2 2s 2 2p 6 configuration and two excited ls 2 2s 2 2p 3 3s and ls 2 2s2p 5 ones of the isoelectronic oxygen series, both with and without taking into account the relativistic corrections. The value of the nuclear charge varies from Z=8 to Z=80. The contribution of relativistic corrections increases with Z. The effect of relativistic corrections on the distance between the centers of gravity of ground and excited configurations increases with Z. The comparison of the results obtained with experimental data is made

Effective interaction for relativistic mean-field theories of nuclear structure

International Nuclear Information System (INIS)

Ai, H.B.; Celenza, L.S.; Harindranath, A.; Shakin, C.M.

1987-01-01

We construct an effective interaction, which when treated in a relativistic Hartree-Fock approximation, reproduces rather accurately the nucleon self-energy in nuclear matter and the Migdal parameters obtained via relativistic Brueckner-Hartree-Fock calculations. This effective interaction is constructed by adding Born terms, describing the exchange of pseudoparticles, to the Born terms of the Dirac-Hartree-Fock analysis. The pseudoparticles have relatively large masses and either real or imaginary coupling constants. (For example, exchange of a pseudo-sigma with an imaginary coupling constant has the effect of reducing the scalar attraction arising from sigma exchange while exchange of a pseudo-omega with an imaginary coupling constant has the effect of reducing the repulsion arising from omega exchange. The terms beyond the Born term in the case of pion exchange are well simulated by pseudo-sigma exchange with a real coupling constant.) The effective interaction constructed here may be used for calculations of the properties of finite nuclei in a relativistic Hartree-Fock approximation

Configuration interaction calculations of positron binding to Be({sup 3}P )

Energy Technology Data Exchange (ETDEWEB)

Bromley, M.W.J. [Department of Physics, San Diego State University, San Diego, CA 92182 (United States)]. E-mail: mbromley@physics.sdsu.edu; Mitroy, J. [Faculty of Technology, Charles Darwin University, Darwin, NT 0909 (Australia)]. E-mail: jxm107@rsphysse.anu.edu.au

2006-06-15

The configuration interaction method is applied to investigate the possibility of positron binding to the metastable beryllium (1s{sup 2}2s2p {sup 3}P ) state. The largest calculation obtained an estimated energy that was unstable by 0.00014 Hartree with respect to the Ps + Be{sup +}(2s) lowest dissociation channel. It is likely that positron binding to parent states with non-zero angular momentum is inhibited by centrifugal barriers.

Relativistic multiple scattering X-alpha calculations

International Nuclear Information System (INIS)

Chermette, H.; Goursot, A.

1986-01-01

The necessity to include self-consistent relativistic corrections in molecular calculations has been pointed out for all compounds involving heavy atoms. Most of the changes in the electronic properties are due to the mass-velocity and the so-called Darwin terms so that the use of Wood and Boring's Hamiltonian is very convenient for this purpose as it can be easily included in MSXalpha programs. Although the spin orbit operator effects are only obtained by perturbation theory, the results compare fairly well with experiment and with other relativistic calculations, namely Hartree-Fock-Slater calculations

Nuclear structure calculations in $^{20}$Ne with No-Core Configuration-Interaction model

OpenAIRE

Konieczka, Maciej; Satuła, Wojciech

2016-01-01

Negative parity states in $^{20}$Ne and Gamow-Teller strength distribution for the ground-state beta-decay of $^{20}$Na are calculated for the very first time using recently developed No-Core Configuration-Interaction model. The approach is based on multi-reference density functional theory involving isospin and angular-momentum projections. Advantages and shortcomings of the method are briefly discussed.

Spin--orbit configuration-interaction study of valence and Rydberg states of LiBe

International Nuclear Information System (INIS)

Marino, M.M.; Ermler, W.C.; Kern, C.W.; Bondybey, V.E.

1992-01-01

Ab initio spin--orbit full configuration-interaction calculations in the context of relativistic effective core potentials are reported for the weakly bound metal dimer LiBe, a three-valence-electron system. The effects of basis set on the energies of valence and Rydberg states of the cluster are discussed, as are the effects of configuration space selection on the energy of the latter states. Results at the dissociative limit are compared to the experimental atomic spectra. Potential-energy curves and spectroscopic constants are presented for the ground state and fourteen excited states, which includes the Li and Be 2p valence states, the Li 3s, 3p, 3d, and 4s Rydberg states, as well as three low-lying states of the molecular cation

Relativistic many-body perturbation-theory calculations based on Dirac-Fock-Breit wave functions

International Nuclear Information System (INIS)

Ishikawa, Y.; Quiney, H.M.

1993-01-01

A relativistic many-body perturbation theory based on the Dirac-Fock-Breit wave functions has been developed and implemented by employing analytic basis sets of Gaussian-type functions. The instantaneous Coulomb and low-frequency Breit interactions are treated using a unified formalism in both the construction of the Dirac-Fock-Breit self-consistent-field atomic potential and in the evaluation of many-body perturbation-theory diagrams. The relativistic many-body perturbation-theory calculations have been performed on the helium atom and ions of the helium isoelectronic sequence up to Z=50. The contribution of the low-frequency Breit interaction to the relativistic correlation energy is examined for the helium isoelectronic sequence

Sensitivity of relativistic impulse approximation proton-nucleus elastic scattering calculations on relativistic mean-field parameterizations

International Nuclear Information System (INIS)

Hojsik, M.; Gmuca, S.

1998-01-01

Relativistic microscopic calculations are presented for proton elastic scattering from 40 Ca at 500 MeV. The underlying target densities are calculated within the framework of the relativistic mean-field theory with several parameter sets commonly in use. The self consistency of the scalar and vector densities (and thus to relativistic mean-field parameters) is investigated. Recently, the relativistic impulse approximation (RIA) has been widely and repeatedly used for the calculations of proton-nucleus scattering at intermediate energies. These calculations have exhibited significant improvements over the nonrelativistic approaches. The relativistic impulse approximation calculations. in particular, provide a dramatically better description of the spin observables, namely the analyzing power, A y , and the spin-rotation function, Q, at least for energies higher than 400 MeV. In the relativistic impulse approximation, the Dirac optical potential is obtained by folding of the local Lorentz-invariant amplitudes with the corresponding nuclear densities. For the spin zero targets the scalar and vector terms give the dominant contributions. Thus the scalar and vector nuclear densities (both, proton and neutron ones) play the dominant role in the relativistic impulse approximation. While the proton vector densities can be obtained by unfolding from the empirically known charge densities, all other densities used rely to a great extent on theoretical models. The various recipes are used to construct the neutron vector densities and the scalar densities for both, neutrons and protons. In this paper we will study the sensitivity of the relativistic impulse approximation results on the various sets of relativistic mean-field parameters currently in use

Matrix elements of the electric multiple transition and relativistic correction operators in the case of complex configurations

International Nuclear Information System (INIS)

Kanyauskas, Yu.M.; Rudzikas, Z.B.

1976-01-01

Operators and their submatrix elements are studied in the framework of the electric multipole transitions of complex atoms with account of relativistic corrections of the order of the square of the fine structure constant. The analysis is performed by means of irreducible tensor operators and genealogical coefficients. It has been assumed that angular momenta of individual shells are coupled with each other according to ls, lk, jk and jj coupling. Formulas are given for the operator which causes the relativistic corrections for the single-electron multipole transition and for its submatrix element in the case of configurations with two unfilled shells. A possibility is discussed of using the formulas suggested for calculation. As follows from analysis, the relativistic correction operators even with the pure ls coupling allow intercombination transitions with ΔS equals +-1. The expressions obtained may turn out to be useful for performing calculations in the case of the intermediate type of coupling

Final-state interactions and relativistic effects in the quasielastic (e,e') reaction

International Nuclear Information System (INIS)

Chinn, C.R.; Physics Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545); Picklesimer, A.; Van Orden, J.W.

1989-01-01

The longitudinal and transverse response functions for the inclusive quasielastic (e,e') reaction are analyzed in detail. A microscopic theoretical framework for the many-body reaction provides a clear conceptual (nonrelativistic) basis for treating final-state interactions and goes far beyond simple plane-wave or Hermitean potential models. The many-body physics of inelastic final-state channels as described by optical and multiple scattering theories is properly included by incorporating a full complex optical potential. Explicit nonrelativistic and relativistic momentum-space calculations quantitatively demonstrate the importance of such a treatment of final-state interactions for both the transverse and longitudinal response. Nonrelativistic calculations are performed using final-state interactions based on phenomenology, local density models, and microscopic multiple scattering theory. Relativistic calculations span a similar range of models and employ Dirac bound-state wave functions. The theoretical extension to relativistic dynamics is of course not clear, but is done in obvious parallel to elastic proton scattering. Extensive calculations are performed for 40 Ca at momentum transfers of 410, 550, and 700 MeV/c. A number of interesting physical effects are observed, including significant relativistic suppressions (especially for R L ), large off-shell and virtual pair effects, enhancement of the tails of the response by the final-state interactions, and large qualitative and even shape distinctions between the predictions of the various models of the final-state interactions. None of the models is found to be able to simultaneously predict the data for both response functions. This strongly suggests that additional physical mechanisms are of qualitative importance in inclusive quasielastic electron scattering

A calculation technique of passing of a powerful relativistic beam through substance

International Nuclear Information System (INIS)

Pobitko, A.I.; Sal'nikov, L.I.; Sukhovitskij, E.Sh.

1995-01-01

The calculation algorithm of passing powerful relativistic beam through substance is developed. Algorithm of calculation is separated on the following problems: 1) a trial charge movement in electromagnetic field of the cylindrical geometry; 2) a computing of own electromagnetic field arising at movement of a particle heavy-current beam in a target; 3) accounting of an interaction of a beam with target atoms; 4) accounting of change of the target properties in a time; 5) geometry and construction of an iterative procedure of calculation. The calculation of passing heavy-current beams of charged particles for transient case is carried out by Monte Carlo method. A conclusion of equations of movement trial charge and technique of calculation own electromagnetic field of the powerful relativistic beam at passing through substance are resulted. 6 refs

Relativistic quasiparticle random-phase approximation calculation of total muon capture rates

International Nuclear Information System (INIS)

Marketin, T.; Paar, N.; Niksic, T.; Vretenar, D.

2009-01-01

The relativistic proton-neutron quasiparticle random phase approximation (pn-RQRPA) is applied in the calculation of total muon capture rates on a large set of nuclei from 12 C to 244 Pu, for which experimental values are available. The microscopic theoretical framework is based on the relativistic Hartree-Bogoliubov (RHB) model for the nuclear ground state, and transitions to excited states are calculated using the pn-RQRPA. The calculation is fully consistent, i.e., the same interactions are used both in the RHB equations that determine the quasiparticle basis, and in the matrix equations of the pn-RQRPA. The calculated capture rates are sensitive to the in-medium quenching of the axial-vector coupling constant. By reducing this constant from its free-nucleon value g A =1.262 by 10% for all multipole transitions, the calculation reproduces the experimental muon capture rates to better than 10% accuracy.

Collision strengths from ground levels of Ti XIII using relativistic-Breit-Pauli approximation

International Nuclear Information System (INIS)

Mohan, M.; Hibbert, H.; Burke, P.G.; Keenan, F.

1998-09-01

The R-matrix method is used to calculate collision strengths from ground state to the first twenty-six fine structure levels of neon-like titanium by including the relativistic term coupling coefficients in the semi-Breit-Pauli approximation. Configuration interaction wave-functions are used to represent the first fifteen lowest LS-coupled target states in the R-matrix expansion. Results obtained are compared with other calculations. This is the first detailed calculation on this ion in which relativistic, exchange, channel couplings and short-range correlation effects are taken into account. (author)

Relativistic Few-Body Hadronic Physics Calculations

Energy Technology Data Exchange (ETDEWEB)

Polyzou, Wayne [Univ. of Iowa, Iowa City, IA (United States)

2016-06-20

The goal of this research proposal was to use ``few-body'' methods to understand the structure and reactions of systems of interacting hadrons (neutrons, protons, mesons, quarks) over a broad range of energy scales. Realistic mathematical models of few-hadron systems have the advantage that they are sufficiently simple that they can be solved with mathematically controlled errors. These systems are also simple enough that it is possible to perform complete accurate experimental measurements on these systems. Comparison between theory and experiment puts strong constraints on the structure of the models. Even though these systems are ``simple'', both the experiments and computations push the limits of technology. The important property of ``few-body'' systems is that the ``cluster property'' implies that the interactions that appear in few-body systems are identical to the interactions that appear in complicated many-body systems. Of particular interest are models that correctly describe physics at distance scales that are sensitive to the internal structure of the individual nucleons. The Heisenberg uncertainty principle implies that in order to be sensitive to physics on distance scales that are a fraction of the proton or neutron radius, a relativistic treatment of quantum mechanics is necessary. The research supported by this grant involved 30 years of effort devoted to studying all aspects of interacting two and three-body systems. Realistic interactions were used to compute bound states of two- and three-nucleon, and two- and three-quark systems. Scattering observables for these systems were computed for a broad range of energies - from zero energy scattering to few GeV scattering, where experimental evidence of sub-nucleon degrees of freedom is beginning to appear. Benchmark calculations were produced, which when compared with calculations of other groups provided an essential check on these complicated calculations. In

Accelerating nuclear configuration interaction calculations through a preconditioned block iterative eigensolver

Science.gov (United States)

Shao, Meiyue; Aktulga, H. Metin; Yang, Chao; Ng, Esmond G.; Maris, Pieter; Vary, James P.

2018-01-01

We describe a number of recently developed techniques for improving the performance of large-scale nuclear configuration interaction calculations on high performance parallel computers. We show the benefit of using a preconditioned block iterative method to replace the Lanczos algorithm that has traditionally been used to perform this type of computation. The rapid convergence of the block iterative method is achieved by a proper choice of starting guesses of the eigenvectors and the construction of an effective preconditioner. These acceleration techniques take advantage of special structure of the nuclear configuration interaction problem which we discuss in detail. The use of a block method also allows us to improve the concurrency of the computation, and take advantage of the memory hierarchy of modern microprocessors to increase the arithmetic intensity of the computation relative to data movement. We also discuss the implementation details that are critical to achieving high performance on massively parallel multi-core supercomputers, and demonstrate that the new block iterative solver is two to three times faster than the Lanczos based algorithm for problems of moderate sizes on a Cray XC30 system.

Quasirelativistic calculation of 4s24p5, 4s24p44d and 4s4p6 configuration spectroscopic parameters for the W39+ ion

International Nuclear Information System (INIS)

Bogdanovich, P; Karpuškienė, R; Kisielius, R

2015-01-01

The ab initio quasirelativistic Hartree–Fock method developed specifically for the calculation of spectral parameters of heavy atoms and highly charged ions is used to derive spectral data for the 4s 2 4p 5 , 4s 2 4p 4 4d and 4s4p 6 configurations of the multicharged tungsten ion W 39+ . The relativistic effects are taken into account in the Breit–Pauli approximation for the quasirelativistic Hartree–Fock radial orbitals. The configuration interaction method is applied to include the electron correlation effects. Produced data are compared with existing experimental measurements and theoretical calculations. (paper)

Relativistic calculations of coalescing binary neutron stars

Indian Academy of Sciences (India)

We have designed and tested a new relativistic Lagrangian hydrodynamics code, which treats gravity in the conformally flat approximation to general relativity. We have tested the resulting code extensively, finding that it performs well for calculations of equilibrium single-star models, collapsing relativistic dust clouds, and ...

Photoabsorption in sodium clusters: first principles configuration interaction calculations

Science.gov (United States)

Priya, Pradip Kumar; Rai, Deepak Kumar; Shukla, Alok

2017-05-01

We present systematic and comprehensive correlated-electron calculations of the linear photoabsorption spectra of small neutral closed- and open-shell sodium clusters (Nan, n = 2 - 6), as well as closed-shell cation clusters (Nan+, n = 3, 5). We have employed the configuration interaction (CI) methodology at the full CI (FCI) and quadruple CI (QCI) levels to compute the ground, and the low-lying excited states of the clusters. For most clusters, besides the minimum energy structures, we also consider their energetically close isomers. The photoabsorption spectra were computed under the electric-dipole approximation, employing the dipole-matrix elements connecting the ground state with the excited states of each isomer. Our calculations were tested rigorously for convergence with respect to the basis set, as well as with respect to the size of the active orbital space employed in the CI calculations. These calculations reveal that as far as electron-correlation effects are concerned, core excitations play an important role in determining the optimized ground state geometries of various clusters, thereby requiring all-electron correlated calculations. But, when it comes to low-lying optical excitations, only valence electron correlation effects play an important role, and excellent agreement with the experimental results is obtained within the frozen-core approximation. For the case of Na6, the largest cluster studied in this work, we also discuss the possibility of occurrence of plasmonic resonance in the optical absorption spectrum. Supplementary material in the form of one pdf file available from the Journal web page at http://https://doi.org/10.1140/epjd/e2017-70728-3

Neutron star equilibrium configurations within a fully relativistic theory with strong, weak, electromagnetic, and gravitational interactions

International Nuclear Information System (INIS)

Belvedere, Riccardo; Pugliese, Daniela; Rueda, Jorge A.; Ruffini, Remo; Xue, She-Sheng

2012-01-01

We formulate the equations of equilibrium of neutron stars taking into account strong, weak, electromagnetic, and gravitational interactions within the framework of general relativity. The nuclear interactions are described by the exchange of the σ, ω, and ρ virtual mesons. The equilibrium conditions are given by our recently developed theoretical framework based on the Einstein–Maxwell–Thomas–Fermi equations along with the constancy of the general relativistic Fermi energies of particles, the “Klein potentials”, throughout the configuration. The equations are solved numerically in the case of zero temperatures and for selected parameterizations of the nuclear models. The solutions lead to a new structure of the star: a positively charged core at supranuclear densities surrounded by an electronic distribution of thickness ∼ℏ/(m e c)∼10 2 ℏ/(m π c) of opposite charge, as well as a neutral crust at lower densities. Inside the core there is a Coulomb potential well of depth ∼m π c 2 /e. The constancy of the Klein potentials in the transition from the core to the crust, imposes the presence of an overcritical electric field ∼(m π /m e ) 2 E c , the critical field being E c =m e 2 c 3 /(eℏ). The electron chemical potential and the density decrease, in the boundary interface, until values μ e crust e core and ρ crust core . For each central density, an entire family of core–crust interface boundaries and, correspondingly, an entire family of crusts with different mass and thickness, exist. The configuration with ρ crust =ρ drip ∼4.3×10 11 gcm −3 separates neutron stars with and without inner crust. We present here the novel neutron star mass–radius for the especial case ρ crust =ρ drip and compare and contrast it with the one obtained from the traditional Tolman–Oppenheimer–Volkoff treatment.

Large-dimension configuration-interaction calculations of positron binding to the group-II atoms

International Nuclear Information System (INIS)

Bromley, M. W. J.; Mitroy, J.

2006-01-01

The configuration-interaction (CI) method is applied to the calculation of the structures of a number of positron binding systems, including e + Be, e + Mg, e + Ca, and e + Sr. These calculations were carried out in orbital spaces containing about 200 electron and 200 positron orbitals up to l=12. Despite the very large dimensions, the binding energy and annihilation rate converge slowly with l, and the final values do contain an appreciable correction obtained by extrapolating the calculation to the l→∞ limit. The binding energies were 0.00317 hartree for e + Be, 0.0170 hartree for e + Mg, 0.0189 hartree for e + Ca, and 0.0131 hartree for e + Sr

Calculation of β-decay rates in a relativistic model with momentum-dependent self-energies

International Nuclear Information System (INIS)

Marketin, T.; Vretenar, D.; Ring, P.

2007-01-01

The relativistic proton-neutron quasiparticle random phase approximation (PN-RQRPA) is applied in the calculation of β-decay half-lives of neutron-rich nuclei in the Z≅28 and Z≅50 regions. The study is based on the relativistic Hartree-Bogoliubov calculation of nuclear ground states, using effective Lagrangians with density-dependent meson-nucleon couplings, and also extended by the inclusion of couplings between the isoscalar meson fields and the derivatives of the nucleon fields. This leads to a linear momentum dependence of the scalar and vector nucleon self-energies. The residual QRPA interaction in the particle-hole channel includes the π+ρ exchange plus a Landau-Migdal term. The finite-range Gogny interaction is employed in the T=1 pairing channel, and the model also includes a proton-neutron particle-particle interaction. The results are compared with available data, and it is shown that an extension of the standard relativistic mean-field framework to include momentum-dependent nucleon self-energies naturally leads to an enhancement of the effective (Landau) nucleon mass, and thus to an improved PN-QRPA description of β - -decay rates

Local unitary transformation method for large-scale two-component relativistic calculations. II. Extension to two-electron Coulomb interaction.

Science.gov (United States)

Seino, Junji; Nakai, Hiromi

2012-10-14

The local unitary transformation (LUT) scheme at the spin-free infinite-order Douglas-Kroll-Hess (IODKH) level [J. Seino and H. Nakai, J. Chem. Phys. 136, 244102 (2012)], which is based on the locality of relativistic effects, has been extended to a four-component Dirac-Coulomb Hamiltonian. In the previous study, the LUT scheme was applied only to a one-particle IODKH Hamiltonian with non-relativistic two-electron Coulomb interaction, termed IODKH/C. The current study extends the LUT scheme to a two-particle IODKH Hamiltonian as well as one-particle one, termed IODKH/IODKH, which has been a real bottleneck in numerical calculation. The LUT scheme with the IODKH/IODKH Hamiltonian was numerically assessed in the diatomic molecules HX and X(2) and hydrogen halide molecules, (HX)(n) (X = F, Cl, Br, and I). The total Hartree-Fock energies calculated by the LUT method agree well with conventional IODKH/IODKH results. The computational cost of the LUT method is reduced drastically compared with that of the conventional method. In addition, the LUT method achieves linear-scaling with respect to the system size and a small prefactor.

Relativistic mean field calculations in neutron-rich nuclei

Energy Technology Data Exchange (ETDEWEB)

Gangopadhyay, G.; Bhattacharya, Madhubrata [Department of Physics, University of Calcutta, 92 Acharya Prafulla Chandra Road, Kolkata 700 009 (India); Roy, Subinit [Saha Institute of Nuclear Physics, Block AF, Sector 1, Kolkata- 700 064 (India)

2014-08-14

Relativistic mean field calculations have been employed to study neutron rich nuclei. The Lagrange's equations have been solved in the co-ordinate space. The effect of the continuum has been effectively taken into account through the method of resonant continuum. It is found that BCS approximation performs as well as a more involved Relativistic Continuum Hartree Bogoliubov approach. Calculations reveal the possibility of modification of magic numbers in neutron rich nuclei. Calculation for low energy proton scattering cross sections shows that the present approach reproduces the density in very light neutron rich nuclei.

Causality and relativistic effects in intranuclear cascade calculations

International Nuclear Information System (INIS)

Kodama, T.; Duarte, S.B.; Chung, K.C.; Donangelo, R.J.; Nazareth, R.A.M.S.

1983-01-01

Relativistic effects in high energy nuclear collisions, when non-invariance of simultaneity is taken into account, are studied. It is shown that the time ordering of nucleon-nucleon collisions is quite different for different observers, giving in some cases non-invariant final results for intranuclear cascade (INC) calculations. In particular, an example of such a case is shown, in which the INC simulation, depending on the reference frame, presents a kind of density instability caused by a specific time ordering of collision events. A new INC calculation, using a causality preserving scheme, which minimizes this kind of relativistic effect is proposed. It is verified that the causality preserving INC prescription essentially recovers the relativistic invariance. (Author) [pt

Inclusive charged-current neutrino-nucleus reactions calculated with the relativistic quasiparticle random-phase approximation

International Nuclear Information System (INIS)

Paar, N.; Vretenar, D.; Marketin, T.; Ring, P.

2008-01-01

Inclusive neutrino-nucleus cross sections are calculated using a consistent relativistic mean-field theoretical framework. The weak lepton-hadron interaction is expressed in the standard current-current form, the nuclear ground state is described with the relativistic Hartree-Bogoliubov model, and the relevant transitions to excited nuclear states are calculated in the relativistic quasiparticle random-phase approximation. Illustrative test calculations are performed for charged-current neutrino reactions on 12 C, 16 O, 56 Fe, and 208 Pb, and results compared with previous studies and available data. Through the use of the experimental neutrino fluxes, the averaged cross sections are evaluated for nuclei of interest for neutrino detectors. We analyze the total neutrino-nucleus cross sections and the evolution of the contribution of the different multipole excitations as a function of neutrino energy. The cross sections for reactions of supernova neutrinos on 16 O and 208 Pb target nuclei are analyzed as functions of the temperature and chemical potential

Leading order relativistic chiral nucleon-nucleon interaction

Science.gov (United States)

Ren, Xiu-Lei; Li, Kai-Wen; Geng, Li-Sheng; Long, Bingwei; Ring, Peter; Meng, Jie

2018-01-01

Motivated by the successes of relativistic theories in studies of atomic/molecular and nuclear systems and the need for a relativistic chiral force in relativistic nuclear structure studies, we explore a new relativistic scheme to construct the nucleon-nucleon interaction in the framework of covariant chiral effective field theory. The chiral interaction is formulated up to leading order with covariant power counting and a Lorentz invariant chiral Lagrangian. We find that the relativistic scheme induces all six spin operators needed to describe the nuclear force. A detailed investigation of the partial wave potentials shows a better description of the {}1S0 and {}3P0 phase shifts than the leading order Weinberg approach, and similar to that of the next-to-leading order Weinberg approach. For the other partial waves with angular momenta J≥slant 1, the relativistic results are almost the same as their leading order non-relativistic counterparts. )

Calculations of configurations of doubly ionized copper (Cu III)

International Nuclear Information System (INIS)

Sugar, J.; Martin, W.C.

1976-01-01

The energy levels belonging to the configurations 3d 7 4s 2 and 3d 8 nl (nl = 4s, 5s, 4p, 5p, 4d, 5d, 4f, and 5g) have been calculated. The radial energy integrals were treated as parameters and adjusted to give a least-squares fit to the observed levels. Two- and three-body effective electrostatic interactions for equivalent electrons were included, as well as two-body effective interactions for inequivalent electrons. Strong configuration interaction between 3d 7 4s 2 and 3d 8 4d was taken into account. Values of the parameters are given for all the above configurations, and the calculated levels are given for all except 3d 8 4s and 3d 8 4p (for which essentially equivalent results have been published). Leading eigenvector percentages are given in appropriate coupling schemes

Relativistic ion acceleration by ultraintense laser interactions

International Nuclear Information System (INIS)

Nakajima, K.; Koga, J.K.; Nakagawa, K.

2001-01-01

There has been a great interest in relativistic particle generation by ultraintense laser interactions with matter. We propose the use of relativistically self-focused laser pulses for the acceleration of ions. Two dimensional PIC simulations are performed, which show the formation of a large positive electrostatic field near the front of a relativistically self-focused laser pulse. Several factors contribute to the acceleration including self-focusing distance, pulse depletion, and plasma density. Ultraintense laser-plasma interactions are capable of generating enormous electrostatic fields of ∼3 TV/m for acceleration of protons with relativistic energies exceeding 1 GeV

New developments in multireference and complete configuration interaction calculations

International Nuclear Information System (INIS)

Knowles, P.J.; Werner, H.J.

1987-01-01

Some recently developed techniques for the calculation of Hamiltonian matrix elements in molecular electronic structure calculations are described. These techniques allow the very rapid calculation, in any desired order, of one particle coupling coefficients between spin symmetry adapted basis functions of arbitrary structure. The matrix elements that are required, for either internally contracted multireference CI calculations, or full CI calculations, are then obtainable from suitable summations over resolutions of the identity, which has been shown previously to be rather efficient; this is especially true on vector computers, since all arithmetic can be formulated as matrix multiplications. These ideas have culminated in the preparation of a new multireference CI program which is capable of handling very large numbers of reference configurations. Application of the new techniques to full CI calculations are also presented

Relativistic QRPA calculation of β-decay rates of r-process nuclei

International Nuclear Information System (INIS)

Marketin, T.; Paar, N.; Niksic, T.

2009-01-01

The rapid neutron-capture process (r-process) is responsible for the creation of many nuclei heavier than iron. To describe the r-process, precise data is needed on a large number of neutron-rich nuclei, most of which are not experimentally reachable. One crucial parameter in modeling the nucleosynthesis are the half-lives of the nuclei through which the r-process runs. Therefore, it is of great importance to develop a reliable predictive model which can be applied to the decay of exotic nuclei. A fully self-consistent calculation of β-decay rates is presented, based on a microscopic theoretical framework. Nuclear ground state is determined using the Relativistic Hartree-Bogoliubov (RHB) model with density-dependent meson-nucleon coupling constants. Momentum dependent terms are also included to improve the density of single-particle states around the Fermi level via an increase of the effective nucleon mass [1]. Transition rates are calculated within the proton-neutron relativistic quasiparticle RPA using the same interaction that was used in the RHB equations. In this way no additional parameters are introduced in the RPA calculation. Weak interaction rates are calculated using the current-current formalism previously employed in the study of other astrophysically significant weak processes [2,3], which systematically includes the contributions of forbidden transitions. This theoretical framework will be utilized to study the contributions of forbidden transitions to the total decay rate in several mass regions. We will compare the calculated half-lives for several isotopic chains with previous calculations and experimental data and discuss possible improvements to the model.(author)

On the relativistic calculation of spontaneous emission

International Nuclear Information System (INIS)

Boudet, R.

1993-01-01

In a recent work, Barut and Salamin (1988) have derived a method for calculating the relativistic decay rates in atoms, in a formulation of quantum electrodynamics based upon the electron's self-energy. The decay rate appears as the imaginary part of a formula giving a complex energy shift, the real part of the formula being the Lamb shift. The presence of the the decay rate in the imaginary part of a formula, giving an energy in its real part, may appear a bit strange. A confirmation of the Barut and Alamin calculation, by means of a quite different point of view, would be useful. Therefore in this work the Einstein A coefficients are calculated, in all cases of degeneracies of the Dirac transition currents, by means of the energy balance method. This point of view is based on the balance between the energy released during the transitions of electrons from a higher state to a lower one, and the flux of the Poynting vector of the classical electromagnetic field, created by the electrons, through a sphere a large radius. The particularity of the present work lies in the direct calculation of the relativistic Dirac transition currents and the fact that the dipole and Pauli approximations are avoided. The quantum part of the relativistic calculation is based on the determination of the transition charge currents in the Darwin solutions of the Dirac equation. 13 refs

Relativistic calculations of one-photon bound-free transition amplitudes in hydrogenic atoms

International Nuclear Information System (INIS)

Simo, E.; Kwato Njock, M.G.

2005-04-01

Photoionization transition matrix of hydrogenic systems are investigated theoretically within the framework of the tensorial formalism with relativistic arguments. Calculations are carried out exactly, without approximation. We derive continuum second-order Dirac-Coulomb Sturmian functions. The numerical simulation of our results is performed in the dipole approximation. We test our theory on selected nucleus from the Periodic Table. The results of the fully relativistic calculations are compared with those of the quasi-relativistic calculations. A conclusion is drawn about the level of reliability of the quite simplified quasi-relativistic approach. (author)

Relativistic description of atomic nuclei

International Nuclear Information System (INIS)

Krutov, V.A.

1985-01-01

Papers on the relativistic description of nuclei are reviewed. The Brown and Rho ''small'' bag'' model is accepted for hardrons. Meson exchange potentials of the nucleon-nucleon interaction have been considered. Then the transition from a system of two interacting nucleons has been performed to the relativistic nucleus description as a multinucleon system on the basis of OBEP (one-boson exchange potential). The proboem of OPEP (one-pion-exchange potential) inclusion to a relativistic scheme is discussed. Simplicity of calculations and attractiveness of the Walecka model for specific computations and calculations was noted. The relativistic model of nucleons interacting through ''effective'' scalar and vector boson fields was used in the Walacka model for describing neutronaand nuclear mater matters

Calculation of relativistic model stars using Regge calculus

International Nuclear Information System (INIS)

Porter, J.

1987-01-01

A new approach to the Regge calculus, developed in a previous paper, is used in conjunction with the velocity potential version of relativistic fluid dynamics due to Schutz [1970, Phys. Rev., D, 2, 2762] to calculate relativistic model stars. The results are compared with those obtained when the Tolman-Oppenheimer-Volkov equations are solved by other numerical methods. The agreement is found to be excellent. (author)

Total cross section for relativistic positronium interaction with atom

International Nuclear Information System (INIS)

Pak, A.S.; Tarasov, A.V.

1985-01-01

Total cross sections of interaction of positronium relativistic atoms with atoms are calculated. Calculations are conducted within the framework of potential theory in Born approximaton. Contributions in total cross section of coherent (σsub(coh)) and incoherent (σsub(inc)) parts are analyzed. It is shown that for light elements σsub(inc) value is comparable with σsub(coh), and for heavy ones the ratio σsub(inc)/σsub(coh) sufficiently exceeds Zsup(-1) (Z-charge of the atomic nucleus. Numerical calculation results are presented. A conclusion is made on importance of the coherent part account during the calculation of total cross sections

Atomic structure calculations using the relativistic random phase approximation

International Nuclear Information System (INIS)

Cheng, K.T.; Johnson, W.R.

1981-01-01

A brief review is given for the relativistic random phase approximation (RRPA) applied to atomic transition problems. Selected examples of RRPA calculations on discrete excitations and photoionization are given to illustrate the need of relativistic many-body theories in dealing with atomic processes where both relativity and correlation are important

Elastic and radiative heavy quark interactions in ultra-relativistic heavy-ion collisions

International Nuclear Information System (INIS)

Uphoff, Jan; Fochler, Oliver; Xu, Zhe; Greiner, Carsten

2015-01-01

Elastic and radiative heavy quark interactions with light partons are studied with the partonic transport model named the Boltzmann approach to multiparton scatterings (BAMPSs). After calculating the cross section of radiative processes for finite masses in the improved Gunion–Bertsch approximation and verifying this calculation by comparing to the exact result, we study elastic and radiative heavy quark energy loss in a static medium of quarks and gluons. Furthermore, the full 3 + 1D space–time evolution of gluons, light quarks, and heavy quarks in ultra-relativistic heavy-ion collisions at the BNL Relativistic Heavy-Ion Collider (RHIC) and the CERN Large Hadron Collider (LHC) are calculated with BAMPS including elastic and radiative heavy flavor interactions. Treating light and heavy particles on the same footing in the same framework, we find that the experimentally measured nuclear modification factor of charged hadrons and D mesons at the LHC can be simultaneously described. In addition, we calculate the heavy flavor evolution with an improved screening procedure from hard-thermal-loop calculations and confront the results with experimental data of the nuclear modification factor and the elliptic flow of heavy flavor particles at the RHIC and the LHC. (paper)

Kramers Pairs in configuration interaction

DEFF Research Database (Denmark)

Avery, John Scales; Avery, James Emil

2003-01-01

The theory of symmetry-preserving Kramers pair creation operators is reviewed and formulas for applying these operators to configuration interaction calculations are derived. A new and more general type of symmetry-preserving pair creation operator is proposed and shown to commute with the total ...

General Relativistic Calculations for White Dwarf Stars

OpenAIRE

Mathew, Arun; Nandy, Malay K.

2014-01-01

The mass-radius relations for white dwarf stars are investigated by solving the Newtonian as well as Tolman-Oppenheimer-Volkoff (TOV) equations for hydrostatic equilibrium assuming the electron gas to be non-interacting. We find that the Newtonian limiting mass of $1.4562M_\\odot$ is modified to $1.4166M_\\odot$ in the general relativistic case for $^4_2$He (and $^{12}_{\\ 6}$C) white dwarf stars. Using the same general relativistic treatment, the critical mass for $^{56}_{26}$Fe white dwarf is ...

Configuration space Faddeev calculations. Progress report, 1 January 1987-31 December 1987

International Nuclear Information System (INIS)

Payne, G.L.; Klink, W.H.; Polyzou, W.N.

1988-01-01

The detailed study of few-body systems provides one of the most sensitive tools for studying nuclear physics at subnucleon distance scales. For these systems the model equations can solved numerically with errors less than the experimental uncertainties. The author have used these systems to investigate the size of relativistic effects, the role of meson-exchange currents, and the importance of quark degrees of freedom in the nucleus. Detailed calculations of the electromagnetic form factors of the deuteron have been done using a front-form formulation of relativistic quantum mechanics. The structure of the most general Poincare covariant electromagnetic current operators and general tensor operators consistent with the dynamical constraints of special relativity was derived. The techniques for constructing scattering amplitudes for multiparticle production reactions have been developed. We have completed a detailed study of the properties of the bound trinucleon system. The solution of the time-dependent Schroedinger in configuration space has been studied. Finally, new computational and analytic tools have been developed

Relativistic transition rates for sextet levels in Cr II

International Nuclear Information System (INIS)

Aashamar, K.; Luke, T.M.

1994-01-01

Configuration interaction calculations have been carried out to obtain rates for electric dipole transitions and lifetimes for the 1s 2 2s 2 2p 6 3s 2 3p 6 3d 4 4d and 5s 6 D and 4d 6 F levels in Cr II. Up to 40 configurations have been included so correlation effects should be well accounted for. Relativistic interactions are included through the use of the Breit-Pauli hamiltonian to obtain the level wave functions and energies. Strong mixing of the 4d levels occurs and this leads to substantial departures from earlier nonrelativistic calculations that assume LS coupling for these states. Results include the actual compositions of both even and odd parity levels where significant mixing occurs and the rates for all transitions that are allowed to lower levels from these 4d and 5s levels. (orig.)

Hylleraas-Configuration Interaction study of the 1S ground state of the negative Li ion.

Science.gov (United States)

Sims, James S

2017-12-28

In a previous work Sims and Hagstrom [J. Chem. Phys. 140, 224312 (2014)] reported Hylleraas-Configuration Interaction (Hy-CI) method variational calculations for the neutral atom and positive ion 1 S ground states of the beryllium isoelectronic sequence. The Li - ion, nominally the first member of this series, has a decidedly different electronic structure. This paper reports the results of a large, comparable calculation for the Li - ground state to explore how well the Hy-CI method can represent the more diffuse L shell of Li - which is representative of the Be(2sns) excited states as well. The best non-relativistic energy obtained was -7.500 776 596 hartree, indicating that 10 - 20 nh accuracy is attainable in Hy-CI and that convergence of the r 12 r 34 double cusp is fast and that this correlation type can be accurately represented within the Hy-CI model.

Calculations of electronic structure of UF6 molecule and crystal UO2 with relativistic pseudopotential

International Nuclear Information System (INIS)

Ehvarestov, R.A.; Panin, A.I.; Bandura, A.V.

2008-01-01

Account of relativistic effects on the properties of uranium hexafluoride is testified. Detailed comparison of single electron energies spectrum revealed in nonrelativistic (by Hartree-Fock method), relativistic (by Dirac-Fock method), and scalar-relativistic (using relativistic potential of atomic uranium frame) has been conducted. Optimization procedures of atomic basis in LCAO calculations of molecules and crystals permissive taking into account distortion of atomic orbitals when chemical bonding are discussed, and optimization effect of atomic basis on the results of scalar-relativistic calculations of UF 6 molecule properties is analyzed. Calculations of electronic structure and properties of UO 2 crystal having relativistic and nonrelativistic pseudopotentials have been realized [ru

First quantized noncritical relativistic Polyakov string

International Nuclear Information System (INIS)

Jaskolski, Z.; Meissner, K.A.

1994-01-01

The first quantization of the relativistic Brink-DiVecchia-Howe-Polyakov (BDHP) string in the range 1 < d 25 is considered. It is shown that using the Polyakov sum over bordered surfaces in the Feynman path integral quantization scheme one gets a consistent quantum mechanics of relativistic 1-dim extended objects in the range 1 < d < 25. In particular, the BDHP string propagator is exactly calculated for arbitrary initial and final string configurations and the Hilbert space of physical states of noncritical BDHP string is explicitly constructed. The resulting theory is equivalent to the Fairlie-Chodos-Thorn massive string model. In contrast to the conventional conformal field theory approach to noncritical string and random surfaces in the Euclidean target space the path integral formulation of the Fairlie-Chodos-Thorn string obtained in this paper does not rely on the principle of conformal invariance. Some consequences of this feature for constructing a consistent relativistic string theory based on the ''splitting-joining'' interaction are discussed. (author). 42 refs, 1 fig

Relativistic Band Calculation and the Optical Properties of Gold

DEFF Research Database (Denmark)

Christensen, N Egede; Seraphin, B. O.

1971-01-01

of magnitude as the gaps (approximately 1 eV). Various integrated functions, density of states, joint density of states, and energy distributions of joint density of states are derived from the RAPW calculation. These functions are used in an interpretation of photoemission and static reflectance measurements......The energy band structure of gold is calculated by the relativistic augmented-plane-wave (RAPW) method. A nonrelativistic calculation is also presented, and a comparison between this and the RAPW results demonstrates that the shifts and splittings due to relativistic effects are of the same order...... to trace out the regions in k→ space where the edge and tail transitions occur. It is demonstrated that structure in the static reflection curves are not related to critical points in the band structure. The arguments are supported by calculations of temperature shifts of the critical-point energies...

Relativistic effects in the intermolecular interaction-induced nuclear magnetic resonance parameters of xenon dimer

DEFF Research Database (Denmark)

Hanni, Matti; Lantto, Perttu; Ilias, Miroslav

2007-01-01

Relativistic effects on the 129Xe nuclear magnetic resonance shielding and 131Xe nuclear quadrupole coupling (NQC) tensors are examined in the weakly bound Xe2 system at different levels of theory including the relativistic four-component Dirac-Hartree-Fock (DHF) method. The intermolecular...... interaction-induced binary chemical shift d, the anisotropy of the shielding tensor ?s, and the NQC constant along the internuclear axis ?ll are calculated as a function of the internuclear distance. DHF shielding calculations are carried out using gauge-including atomic orbitals. For comparison, the full...... is obtained for d and ?s in Xe2. For these properties, the currently most complete theoretical description is obtained by a piecewise approximation where the uncorrelated relativistic DHF results obtained close to the basis-set limit are corrected, on the one hand, for NR correlation effects and, on the other...

Calculating Relativistic Transition Matrix Elements for Hydrogenic Atoms Using Monte Carlo Methods

Science.gov (United States)

Alexander, Steven; Coldwell, R. L.

2015-03-01

The nonrelativistic transition matrix elements for hydrogen atoms can be computed exactly and these expressions are given in a number of classic textbooks. The relativistic counterparts of these equations can also be computed exactly but these expressions have been described in only a few places in the literature. In part, this is because the relativistic equations lack the elegant simplicity of the nonrelativistic equations. In this poster I will describe how variational Monte Carlo methods can be used to calculate the energy and properties of relativistic hydrogen atoms and how the wavefunctions for these systems can be used to calculate transition matrix elements.

Modeling nuclear weak-interaction processes with relativistic energy density functionals

International Nuclear Information System (INIS)

Paar, N.; Marketin, T.; Vale, D.; Vretenar, D.

2015-01-01

Relativistic energy density functionals have become a standard framework for nuclear structure studies of ground state properties and collective excitations over the entire nuclide chart. In this paper, we review recent developments in modeling nuclear weak-interaction processes: Charge-exchange excitations and the role of isoscalar proton–neutron pairing, charged-current neutrino–nucleus reactions relevant for supernova evolution and neutrino detectors and calculation of β-decay rates for r-process nucleosynthesis. (author)

An Ada environment for relativistic cross section calculations

International Nuclear Information System (INIS)

Nilsson, E.

1990-01-01

We have developed an Ada environment adapted to relativistic cross section calculations. Objects such as four-vectors, γ- matrices and propagators are defined as well as operations between these objects. In this environment matrix elements can be expressed in a compact and readable way as Ada code. Unpolarized cross sections are calculated numerically by explicitly summing and averaging over spins and polarizations. A short presentation of the technique is given

Relativistic many-body calculations of magnetic dipole transitions in Be-like ions

International Nuclear Information System (INIS)

Safronova, U.I.; Johnson, W.R.; Derevianko, A.

1999-01-01

Reduced matrix elements and transition rates are calculated for all magnetic dipole (M1) transitions within 2l2l' configurations and for some 2l3l'-2l2l' transitions in Be-like ions with nuclear charges ranging from Z = 4 to 100. Many-body perturbation theory (MBPT), including the Breit interaction, is used to evaluate retarded M1 matrix elements. The calculations start with a (1s) 2 Dirac-Fock potential and include all possible n = 2 configurations, leading to 4 odd-parity and 6 even-parity states, and some n = 3 configurations. First-order perturbation theory is used to obtain intermediate coupling coefficients. Second-order MBPT is used to determine the matrix elements, which are evaluated for all 11 M1 transitions within 2l2l' configurations and for 35 M1 transitions between 2l3l' and 2l2l' states. The transition energies used in the calculation of oscillator strengths and transition rates are obtained from second-order MBPT. The importance of negative-energy contributions to M1 transition amplitudes is discussed. (orig.)

Gauge origin independent calculations of molecular magnetisabilities in relativistic four-component theory

DEFF Research Database (Denmark)

Iliaš, M.; Jensen, Hans Jørgen Aagaard; Bast, R.

2013-01-01

of the four-component relativistic linear response method at the self-consistent field single reference level. Benefits of employing the London atomic orbitals in relativistic calculations are illustrated with Hartree-Fock wave functions on the XF3 (X = N, P, As, Sb, Bi) series of molecules. Significantly...

The Einstein A-coefficient of spontaneous emission: A relativistic calculation in the Heisenberg representation

International Nuclear Information System (INIS)

Barut, A.O.; Salamin, Y.I.

1989-07-01

We present a simple approach to the relativistic calculation of the rates of spontaneous emission starting from the Heisenberg picture formula for the power radiated by a charged particle undergoing acceleration, and evaluate atomic decay rates using relativistic Dirac-Coulomb wavefunctions. The spin of the electron, embedded in its relativistic wavefunction, is shown to correctly provide the two polarization states of the emitted radiation. We discuss selection rules and calculate the Hydrogen 2 P → 1 S transition rate, among others, to be Γ = (6.2650 ± 0.0007)x10 8 s -1 in good agreement with the full field theory calculation as well as with experiment. (author). 14 refs

Modelling properties of hard x-rays generated by the interaction between relativistic electrons and very intense laser beams

International Nuclear Information System (INIS)

Popa, Alexandru

2009-01-01

In a previous paper we presented a calculation model for high harmonic generation by relativistic Thomson scattering of the electromagnetic radiation by free electrons. In this paper we present a similar model for the calculation of the energies of hard x-rays (20- 200 keV) resulted from the interaction between relativistic electrons (20-100 MeV) and very intense laser beams. Starting from the relativistic equations of motion of an electron in the electromagnetic field we show that the Lienard-Wiechert equation leads to electromagnetic waves whose frequencies are in the domain of hard x-rays. When the relativistic parameter of the laser beam is greater than unity, the model predicts the existence of harmonics of the above frequencies. Our theoretical values are in good agreement with experimental values of the x-ray energies from the literature and predict accurately their angular distribution.

Consideration of relativistic effects in band structure calculations based on the empirical tight-binding method

International Nuclear Information System (INIS)

Hanke, M.; Hennig, D.; Kaschte, A.; Koeppen, M.

1988-01-01

The energy band structure of cadmium telluride and mercury telluride materials is investigated by means of the tight-binding (TB) method considering relativistic effects and the spin-orbit interaction. Taking into account relativistic effects in the method is rather simple though the size of the Hamilton matrix doubles. Such considerations are necessary for the interesting small-interstice semiconductors, and the experimental results are reflected correctly in the band structures. The transformation behaviour of the eigenvectors within the Brillouin zone gets more complicated, but is, nevertheless, theoretically controllable. If, however, the matrix elements of the Green operator are to be calculated, one has to use formula manipulation programmes in particular for non-diagonal elements. For defect calculations by the Koster-Slater theory of scattering it is necessary to know these matrix elements. Knowledge of the transformation behaviour of eigenfunctions saves frequent diagonalization of the Hamilton matrix and thus permits a numerical solution of the problem. Corresponding results for the sp 3 basis are available

Four-Component Relativistic Density-Functional Theory Calculations of Nuclear Spin-Rotation Constants: Relativistic Effects in p-Block Hydrides.

Science.gov (United States)

Komorovsky, Stanislav; Repisky, Michal; Malkin, Elena; Demissie, Taye B; Ruud, Kenneth

2015-08-11

We present an implementation of the nuclear spin-rotation (SR) constants based on the relativistic four-component Dirac-Coulomb Hamiltonian. This formalism has been implemented in the framework of the Hartree-Fock and Kohn-Sham theory, allowing assessment of both pure and hybrid exchange-correlation functionals. In the density-functional theory (DFT) implementation of the response equations, a noncollinear generalized gradient approximation (GGA) has been used. The present approach enforces a restricted kinetic balance condition for the small-component basis at the integral level, leading to very efficient calculations of the property. We apply the methodology to study relativistic effects on the spin-rotation constants by performing calculations on XHn (n = 1-4) for all elements X in the p-block of the periodic table and comparing the effects of relativity on the nuclear SR tensors to that observed for the nuclear magnetic shielding tensors. Correlation effects as described by the density-functional theory are shown to be significant for the spin-rotation constants, whereas the differences between the use of GGA and hybrid density functionals are much smaller. Our calculated relativistic spin-rotation constants at the DFT level of theory are only in fair agreement with available experimental data. It is shown that the scaling of the relativistic effects for the spin-rotation constants (varying between Z(3.8) and Z(4.5)) is as strong as for the chemical shieldings but with a much smaller prefactor.

Relativistic mechanics of two interacting particles and bilocal theory

International Nuclear Information System (INIS)

Takabayasi, Takehiko

1975-01-01

New relativistic mechanics of two-particle system is set forth, where the two constituent particles are interacting by an arbitrary (central) action-at-a-distance. The fundamental equations are presented in a form covariant under general transformation of parameters parametrizing the world lines of constituent particles. The theory represents the proper relativistic generalization of the usual Newtonian mechanics in the sense that it tends in the non-relativistic (and weak interaction) limit to the usual mechanics of two particles moving under a corresponding non-relativistic potential. For the analysis of theory it is convenient to choose a certain particular gauge (i.e., parametrization) fixed by two gauge relations. This brings the theory to a canonical formalism accompanied by two weak equations, and in this gauge quantization can be performed. The result verifies that the relativistic quantum mechanics for two particles interacting by an action-at-a-distance is just represented by a bilocal wave equation and a subsidiary condition, with the clarification of its correspondence-theoretical foundation and internal dynamics. As an example the case of Hooke-type force is illustrated, where the internal motions are elliptic oscillations in the center-of-mass frame. Its quantum theory just reproduces the original form of bilocal theory giving bound states lying on a straightly rising trajectory and on its daughter trajectories. (auth.)

Relativistic effects in bonding and dipole moments for the diatomic hydrides of the sixth-row heavy elements

International Nuclear Information System (INIS)

Ramos, A.F.; Pyper, N.C.; Malli, G.L.

1988-01-01

Ab initio Dirac-Fock (DF) and nonrelativistic-limit (NRL) wave functions and dipole moments are calculated to investigate the bonding characteristics and the relativistic effects in the systems HgH + , TlH, PbH + , and BiH. The dipole moment of AuH is evaluated using the DF self-consistent field and relativistic configuration-interaction wave functions obtained by G. L. Malli and N. C. Pyper [Proc. R. Soc. London, Ser. A 407, 377 (1986)]. Contour plots of relativistic molecular orbital densities and difference density maps are presented to illustrate the arrangement of electronic charge in these systems. It is found that the 5d orbitals are involved in the bonding of HgH + , whereas they do not play a significant role in TlH and PbH + . The relativistic calculations predict HgH + , TlH, and PbH + to be bound. The nonrelativistic-limit wave functions predict HgH + and BiH to be unbound but TlH and PbH + to be bound. It is also found that the calculated dipole moments using the DF and the NRL wave functions for these heavy systems differ significantly in magnitude, and in some cases even in the sign

Relativistic direct interaction and hadron models

International Nuclear Information System (INIS)

Biswas, T.

1984-01-01

Direct interaction theories at a nonrelativistic level have been used successfully in several areas earlier (e.g. nuclear physics). But for hadron spectroscopy relativistic effects are important and hence the need for a relativistic direct interaction theory arises. It is the goal of this thesis to suggest such a theory which has the simplicity and the flexibility required for phenomenological model building. In general the introduction of relativity in a direct interaction theory is shown to be non-trivial. A first attempt leads to only an approximate form for allowed interactions. Even this is far too complex for phenomenological applicability. To simplify the model an extra spacelike particle called the vertex is introduced in any set of physical (timelike) particles. The vertex model is successfully used to fit and to predict experimental data on hadron spectra, γ and psi states fit very well with an interaction function inspired by QCD. Light mesons also fit reasonably well. Better forms of hyperfine interaction functions would be needed to improve the fitting of light mesons. The unexpectedly low pi meson mass is partially explained. Baryon ground states are fitted with unprecedented accuracy with very few adjustable parameters. For baryon excited states it is shown that better QCD motivated interaction functions are needed for a fit. Predictions for bb states in e + e - experiments are made to assist current experiments

Large-scale parallel configuration interaction. II. Two- and four-component double-group general active space implementation with application to BiH

DEFF Research Database (Denmark)

Knecht, Stefan; Jensen, Hans Jørgen Aagaard; Fleig, Timo

2010-01-01

We present a parallel implementation of a large-scale relativistic double-group configuration interaction CIprogram. It is applicable with a large variety of two- and four-component Hamiltonians. The parallel algorithm is based on a distributed data model in combination with a static load balanci...

Interaction of high-current relativistic electron beams with plasma. Physical nature of the phenomenon and its application in microwave electronics

International Nuclear Information System (INIS)

Rukhadze, A.A.

1981-01-01

Pulsed high-current electron beams with characteristic parameters: electron energy 10 5 -10 7 eV, electron current 10 3 -10 6 A, pulse duration 10 -8 -10 -6 s, beam energy 10 2 -10 6 J and power 10 8 -10 13 W, are widely used in different branches of science and technology such as controlled thermonuclear fusion, relativistic microwave electronics, powerful semiconductors, chemical and gaseous lasers, new principles of heavy-ion acceleration, and long-distance energy transmission. The paper discusses a new branch of science - pulsed high-current electronics, which has its own experimental technique and methods of theoretical analysis. Parts I and II determine what is meant by ''high current'' in an electron beam and calculate the maximum obtainable current values; these calculations are made for the simplest geometrical configurations realizable in practice. Current methods for theoretical analysis of high-current electron beam physics are described, together with classification of current experimental devices for generating such beams according to high-current parameters. The stability of electron beams is discussed and the concept of critical currents is introduced. Part III gives a detailed account of plasma-beam instability which occurs on the interaction of a high-current electron beam with high-density space-limited plasma. The linear and non-linear stages of beam instability are considered. The given theory is used for calculations for amplifiers and microwave generators of electromagnetic radiation. Finally, the experimental achievements in high-current relativistic microwave electronics are reviewed. (author)

Accelerating Full Configuration Interaction Calculations for Nuclear Structure

International Nuclear Information System (INIS)

Yang, Chao; Sternberg, Philip; Maris, Pieter; Ng, Esmond; Sosonkina, Masha; Le, Hung Viet; Vary, James; Yang, Chao

2008-01-01

One of the emerging computational approaches in nuclear physics is the full configuration interaction (FCI) method for solving the many-body nuclear Hamiltonian in a sufficiently large single-particle basis space to obtain exact answers - either directly or by extrapolation. The lowest eigenvalues and corresponding eigenvectors for very large, sparse and unstructured nuclear Hamiltonian matrices are obtained and used to evaluate additional experimental quantities. These matrices pose a significant challenge to the design and implementation of efficient and scalable algorithms for obtaining solutions on massively parallel computer systems. In this paper, we describe the computational strategies employed in a state-of-the-art FCI code MFDn (Many Fermion Dynamics - nuclear) as well as techniques we recently developed to enhance the computational efficiency of MFDn. We will demonstrate the current capability of MFDn and report the latest performance improvement we have achieved. We will also outline our future research directions

Coupled-Cluster and Configuration-Interaction Calculations for Heavy Nuclei

International Nuclear Information System (INIS)

Horoi, M.; Gour, J. R.; Wloch, M.; Lodriguito, M. D.; Brown, B. A.; Piecuch, P.

2007-01-01

We compare coupled-cluster (CC) and configuration-interaction (CI) results for 56 Ni obtained in the pf-shell basis, focusing on practical CC approximations that can be applied to systems with dozens or hundreds of correlated fermions. The weight of the reference state and the strength of correlation effects are controlled by the gap between the f 7/2 orbit and the f 5/2 , p 3/2 , p 1/2 orbits. Independent of the gap, the CC method with 1p-1h and 2p-2h clusters and a noniterative treatment of 3p-3h clusters is as accurate as the more demanding CI approach truncated at the 4p-4h level

Relativistic spin-orbit interactions of photons and electrons

Science.gov (United States)

Smirnova, D. A.; Travin, V. M.; Bliokh, K. Y.; Nori, F.

2018-04-01

Laboratory optics, typically dealing with monochromatic light beams in a single reference frame, exhibits numerous spin-orbit interaction phenomena due to the coupling between the spin and orbital degrees of freedom of light. Similar phenomena appear for electrons and other spinning particles. Here we examine transformations of paraxial photon and relativistic-electron states carrying the spin and orbital angular momenta (AM) under the Lorentz boosts between different reference frames. We show that transverse boosts inevitably produce a rather nontrivial conversion from spin to orbital AM. The converted part is then separated between the intrinsic (vortex) and extrinsic (transverse shift or Hall effect) contributions. Although the spin, intrinsic-orbital, and extrinsic-orbital parts all point in different directions, such complex behavior is necessary for the proper Lorentz transformation of the total AM of the particle. Relativistic spin-orbit interactions can be important in scattering processes involving photons, electrons, and other relativistic spinning particles, as well as when studying light emitted by fast-moving bodies.

Configuration space Faddeev calculations

International Nuclear Information System (INIS)

Payne, G.L.; Klink, W.H.; Polyzou, W.N.

1992-12-01

The detailed study of few-body systems provides one of the most precise tools for studying the dynamics of nuclei and nucleons. This research program consists of a careful theoretical study of few-body systems and methods for modeling these systems. During the past year several aspects of this program were completed. Brief summaries are given of work on the following topics: The relativistic three quark problem; the relativistic Balian-Brezin method; spin in light front quantum mechanical models; proton-deutron scattering and reactions; point form relativistic quantum mechanics of constituents; solutions of quantum mechanical anharmonic oscillators; shift operators and the U(N) multiplicity problem

Configuration interaction calculations for the region of 76Ge

Science.gov (United States)

Brown, Alex

2017-09-01

I will present a short history of the configuration interaction Hamiltonians that have been developed for the (0f5 / 2 , 1p3 / 2 , 1p1 / 2 , 0g9 / 2) (jj 44) model space. This model space is appropriate for the region of nuclei bounded by the nickel isotopes for Z = 28 and the isotones with N = 50 . I will discuss results for the double-beta decay of 76Ge that lies in the jj 44 region. I will show results for the structure of nuclei around 76Ge for some selected data from gamma decay, Gamow-Teller beta decay, charge-exchange reactions, one-nucleon transfer reactions, and two-nucleon transfer reactions. This work was supported by NSF Grant PHY-1404442.

Relativistic strings and dual models of strong interactions

International Nuclear Information System (INIS)

Marinov, M.S.

1977-01-01

The theory of strong interactions,based on the model depicting a hardon as a one-dimentional elastic relativistic system(''string'') is considered. The relationship between this model and the concepts of quarks and partons is discussed. Presented are the principal results relating to the Veneziano dual theory, which may be considered as the consequence of the string model, and to its modifications. The classical string theory is described in detail. Attention is focused on questions of importance to the construction of the quantum theory - the Hamilton mechanisms and conformal symmetry. Quantization is described, and it is shown that it is not contradictory only in the 26-dimentional space and with a special requirement imposed on the spectrum of states. The theory of a string with a distributed spin is considered. The spin is introduced with the aid of the Grassman algebra formalism. In this case quantization is possible only in the 10-dimentional space. The strings interact by their ruptures and gluings. A method for calculating the interaction amplitudes is indicated

Calculation of the RPA response function of nuclei to quasi-elastic electron scattering with a density-dependent NN interaction

International Nuclear Information System (INIS)

Caillon, J-C.; Labarsouque, J.

1997-01-01

So far, the non-relativistic longitudinal and transverse functions in electron quasi-elastic scattering on the nuclei failed in reproducing satisfactorily the existent experimental data. The calculations including relativistic RPA correlations utilize until now the relativistic Hartree approximation to describe the nuclear matter. But, this provides an incompressibility module two times higher than its experimental value what is an important drawback for the calculation of realistic relativistic RPA correlations. Hence, we have determined the RPA response functions of nuclei by utilising a description of the relativistic nuclear matter leading to an incompressibility module in agreement with the empirical value. To do that we have utilized an interaction in the relativistic Hartree approximation in which we have determined the coupling constants σ-N and ω-N as a function of the density in order to reproduce the saturation curve obtained by a Dirac-Brueckner calculation. The results which we have obtained show that the longitudinal response function and the Coulomb sum generally overestimated when one utilizes the pure relativistic Hartree approximation, are here in good agreement with the experimental data for several nuclei

Calculations of relativistic effects in atoms and molecules from the Schroedinger wave function

International Nuclear Information System (INIS)

Detrich, J.H.; Roothaan, C.C.J.

1981-01-01

The traditional method for dealing with relativistic effects in atoms and molecules consists of a somewhat heuristic combination of quantum electrodynamics and a many-electron quantum mechanics generalized from the one-electron Dirac theory. On the whole, results calculated from this theory agree with experimental data. Nevertheless, the theory is by no means entirely satisfactory; in its development, certain ambiguities and divergencies must be resolved by somewhat arbitrary and/or questionable means. This paper illuminates - and sidesteps - some of the more questionable aspects of the traditional method, by reformulating electromagnetic interactions between particles in a different way

A High Performance Block Eigensolver for Nuclear Configuration Interaction Calculations

International Nuclear Information System (INIS)

Aktulga, Hasan Metin; Afibuzzaman, Md.; Williams, Samuel; Buluc, Aydin; Shao, Meiyue

2017-01-01

As on-node parallelism increases and the performance gap between the processor and the memory system widens, achieving high performance in large-scale scientific applications requires an architecture-aware design of algorithms and solvers. We focus on the eigenvalue problem arising in nuclear Configuration Interaction (CI) calculations, where a few extreme eigenpairs of a sparse symmetric matrix are needed. Here, we consider a block iterative eigensolver whose main computational kernels are the multiplication of a sparse matrix with multiple vectors (SpMM), and tall-skinny matrix operations. We then present techniques to significantly improve the SpMM and the transpose operation SpMM T by using the compressed sparse blocks (CSB) format. We achieve 3-4× speedup on the requisite operations over good implementations with the commonly used compressed sparse row (CSR) format. We develop a performance model that allows us to correctly estimate the performance of our SpMM kernel implementations, and we identify cache bandwidth as a potential performance bottleneck beyond DRAM. We also analyze and optimize the performance of LOBPCG kernels (inner product and linear combinations on multiple vectors) and show up to 15× speedup over using high performance BLAS libraries for these operations. The resulting high performance LOBPCG solver achieves 1.4× to 1.8× speedup over the existing Lanczos solver on a series of CI computations on high-end multicore architectures (Intel Xeons). We also analyze the performance of our techniques on an Intel Xeon Phi Knights Corner (KNC) processor.

Configuration space Faddeev calculations: Progress report for period 1 January 1986-31 December 1986

International Nuclear Information System (INIS)

Payne, G.L.; Klink, W.H.; Polyzou, W.N.

1987-01-01

The detailed study of few-body nuclear systems provides a powerful tool to identify the relevant degrees of freedom in the nucleus. For these systems one can perform detailed and accurate numerical calculations which can be used to study the interactions between the various degrees of freedom. We have used these systems to investigate the size of the relativistic effects, the role of meson exchange currents, and the importance of the quark degrees of freedom in the nuclear system. New computational tools have been developed to treat relativistic operators. The effects of the Coulomb polarization potential on the low-energy scattering parameters have been investigated, and the effects of the Coulomb interaction on charge symmetry breaking have been studied. We have continued our project to find representations for multiparticle scattering amplitudes which satisfy certain physical properties. Finally, we have extended our work on the realization of the irreducible representations of compact groups as spaces of polynomials. These realizations can then be used in a symbolic manipulation program to generate Clebsch-Gordan and Racah coefficients for groups important in nuclear physics applications. 37 refs

Fermi liquid description of relativistic high density matter

Science.gov (United States)

Pal, K.; Dutt-Mazumder, A. K.

2011-06-01

We calculate pionic contribution to the relativistic Fermi Liquid parameters (RFLPs) using Chiral Effective Lagrangian. The RFLPs so determined are then used to calculate chemical potential, exchange energy due to πN interaction. We also compare the results of exchange energy from two loop ring diagrams involving σ, ω and π meson with what one obtains from the relativistic Fermi Liquid theory (RFLT).

Relativistic stability of interacting Fermi gas in a strong magnetic field

International Nuclear Information System (INIS)

Wang Lilin; Tian Jincheng; Men Fudian; Zhang Yipeng

2013-01-01

By means of the single particle energy spectrum of weak interaction between fermions and Poisson formula, the thermodynamic potential function of relativistic Fermi gas in a strong magnetic field is derived. Based on this, we obtained the criterion of stability for the system. The results show that the mechanics stability of a Fermi gas with weak interacting is influenced by the interacting. While the magnetic field is able to regulate the influence and the relativistic effect has almost no effect on it. (authors)

Relativistic coupled-cluster calculations of 20Ne, 40Ar, 84Kr, and 129Xe: Correlation energies and dipole polarizabilities

International Nuclear Information System (INIS)

Mani, B. K.; Angom, D.; Latha, K. V. P.

2009-01-01

We have carried out a detailed and systematic study of the correlation energies of inert gas atoms Ne, Ar, Kr, and Xe using relativistic many-body perturbation theory and relativistic coupled-cluster theory. In the relativistic coupled-cluster calculations, we implement perturbative triples and include these in the correlation energy calculations. We then calculate the dipole polarizability of the ground states using perturbed coupled-cluster theory.

Quasiparticle method in relativistic mean-field theories of nuclear structure

International Nuclear Information System (INIS)

Ai, H.

1988-01-01

In recent years, in order to understand the success of Dirac phenomenology, relativistic Brueckner-Hartree-Fock (RBHF) theory has been developed. This theory is a relativistic many-body theory of nuclear structure. Based upon the RBHF theory, which is characterized as having no free parameters other than those introduced in fitting free-space nucleon-nucleon scattering data, we construct an effective interaction. This interaction, when treated in a relativistic Hartree-Fock approximation, reproduces, rather accurately, the nucleon self-energy in nuclear matter, Migdal parameters obtained via relativistic Brueckner-Hartree-Fock calculations, and the saturation curves calculated with the full relativistic Brueckner-Hartree-Fock theory. This effective interaction is constructed by adding a number of pseudoparticles to the mesons used to construct one-boson-exchange (OBE) models of the nuclear force. The pseudoparticles have relatively large masses and either real or imaginary coupling constants. (For example, exchange of a pseudo-sigma with an imaginary coupling constant has the effect of reducing the scalar attraction arising from sigma exchange, while exchange of a pseudo-omega with an imaginary coupling constant has the effect of reducing the repulsion arising from omega exchange. The terms beyond the Born term in the case of pion exchange are well simulated by pseudo-sigma exchange with a real coupling constant.) The effective interaction constructed here may be used for calculations of the properties of finite nuclei in a relativistic Hartree-Fock approximation

Chemistry of the 5g Elements: Relativistic Calculations on Hexafluorides.

Science.gov (United States)

Dognon, Jean-Pierre; Pyykkö, Pekka

2017-08-14

A Periodic System was proposed for the elements 1-172 by Pyykkö on the basis of atomic and ionic calculations. In it, the elements 121-138 were nominally assigned to a 5g row. We now perform molecular, relativistic four-component DFT calculations and find that the hexafluorides of the elements 125-129 indeed enjoy occupied 5g states. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chemistry of the 5g elements. Relativistic calculations on hexafluorides

International Nuclear Information System (INIS)

Dognon, Jean-Pierre; Pyykkoe, Pekka

2017-01-01

A Periodic System was proposed for the elements 1-172 by Pyykkoe on the basis of atomic and ionic calculations. In it, the elements 121-138 were nominally assigned to a 5g row. We now perform molecular, relativistic four-component DFT calculations and find that the hexafluorides of the elements 125-129 indeed enjoy occupied 5g states. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

Chemistry of the 5g elements. Relativistic calculations on hexafluorides

Energy Technology Data Exchange (ETDEWEB)

Dognon, Jean-Pierre [NIMBE, CEA, CNRS, Universite Paris-Saclay, CEA Saclay, Gif-sur-Yvette (France); Pyykkoe, Pekka [Department of Chemistry, University of Helsinki (Finland)

2017-08-14

A Periodic System was proposed for the elements 1-172 by Pyykkoe on the basis of atomic and ionic calculations. In it, the elements 121-138 were nominally assigned to a 5g row. We now perform molecular, relativistic four-component DFT calculations and find that the hexafluorides of the elements 125-129 indeed enjoy occupied 5g states. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

Relativistic mean field model for entrainment in general relativistic superfluid neutron stars

International Nuclear Information System (INIS)

Comer, G.L.; Joynt, R.

2003-01-01

General relativistic superfluid neutron stars have a significantly more intricate dynamics than their ordinary fluid counterparts. Superfluidity allows different superfluid (and superconducting) species of particles to have independent fluid flows, a consequence of which is that the fluid equations of motion contain as many fluid element velocities as superfluid species. Whenever the particles of one superfluid interact with those of another, the momentum of each superfluid will be a linear combination of both superfluid velocities. This leads to the so-called entrainment effect whereby the motion of one superfluid will induce a momentum in the other superfluid. We have constructed a fully relativistic model for entrainment between superfluid neutrons and superconducting protons using a relativistic σ-ω mean field model for the nucleons and their interactions. In this context there are two notions of 'relativistic': relativistic motion of the individual nucleons with respect to a local region of the star (i.e. a fluid element containing, say, an Avogadro's number of particles), and the motion of fluid elements with respect to the rest of the star. While it is the case that the fluid elements will typically maintain average speeds at a fraction of that of light, the supranuclear densities in the core of a neutron star can make the nucleons themselves have quite high average speeds within each fluid element. The formalism is applied to the problem of slowly rotating superfluid neutron star configurations, a distinguishing characteristic being that the neutrons can rotate at a rate different from that of the protons

Relativistic electron mirrors from high intensity laser nanofoil interactions

International Nuclear Information System (INIS)

Kiefer, Daniel

2012-01-01

The reflection of a laser pulse from a mirror moving close to the speed of light could in principle create an X-ray pulse with unprecedented high brightness owing to the increase in photon energy and accompanying temporal compression by a factor of 4γ 2 , where γ is the Lorentz factor of the mirror. While this scheme is theoretically intriguingly simple and was first discussed by A. Einstein more than a century ago, the generation of a relativistic structure which acts as a mirror is demanding in many different aspects. Recently, the interaction of a high intensity laser pulse with a nanometer thin foil has raised great interest as it promises the creation of a dense, attosecond short, relativistic electron bunch capable of forming a mirror structure that scatters counter-propagating light coherently and shifts its frequency to higher photon energies. However, so far, this novel concept has been discussed only in theoretical studies using highly idealized interaction parameters. This thesis investigates the generation of a relativistic electron mirror from a nanometer foil with current state-of-the-art high intensity laser pulses and demonstrates for the first time the reflection from those structures in an experiment. To achieve this result, the electron acceleration from high intensity laser nanometer foil interactions was studied in a series of experiments using three inherently different high power laser systems and free-standing foils as thin as 3nm. A drastic increase in the electron energies was observed when reducing the target thickness from the micrometer to the nanometer scale. Quasi-monoenergetic electron beams were measured for the first time from ultrathin (≤5nm) foils, reaching energies up to ∝35MeV. The acceleration process was studied in simulations well-adapted to the experiments, indicating the transition from plasma to free electron dynamics as the target thickness is reduced to the few nanometer range. The experience gained from those

Relativistic actions for bound-states and applications in the meson spectroscopy

International Nuclear Information System (INIS)

Silva Carvalho, Hendly da.

1991-08-01

We study relativistic equations for bound states of two-body systems using Dirac's constraint formalism and supersymmetry. The two-body system can be of spinless particles, one of them spinning and the other one spinless, or both of them spinning. The interaction is described by scalar, timelike four-vector and spacelike four-vector potentials under Lorentz transformations. As an application we use the relativistic wave equation for two scalar particles and calculate the mass spectra of the mesons treating them as spinless quark-antiquark bound states. The interaction potential in this case is a convenient adaptation of the potential employed in non-relativistic calculations. Finally, we compare our results with more recent experimental data and with theoretical results obtained with the same potential used by us but with a non-relativistic wave equation. We also compare our results with results obtained with the relativistic wave equation but with a different interaction potential. (author). 38 refs, 9 figs, 8 tabs

Fermi liquid description of relativistic high density matter

International Nuclear Information System (INIS)

Pal, K.; Dutt-Mazumder, A.K.

2011-01-01

We calculate pionic contribution to the relativistic Fermi Liquid parameters (RFLPs) using Chiral Effective Lagrangian. The RFLPs so determined are then used to calculate chemical potential, exchange energy due to πN interaction. We also compare the results of exchange energy from two loop ring diagrams involving σ, ω and π meson with what one obtains from the relativistic Fermi Liquid theory (RFLT). (author)

Unusual behavior of projectile fragments formed in the bombardment of copper with relativistic Ar ions

International Nuclear Information System (INIS)

Dersch, G.; Beckmann, R.; Feige, G.

1985-01-01

The interaction properties of projectile fragments from the fragmentation of 0.9 GeV/nucleon and 1.8 GeV/nucleon 40 Ar with Cu have been studied using radioactivation techniques. In this experiment, two identical copper blocks, 1 cm thick and 8 cm in diameter, are irradiated by relativistic projectiles in different configurations. In configuration 0, the blocks are touching while in configuration 10 or 20, the blocks are separated by 10 or 20 cm of air, respectively. It is assumed that when the relativistic projectiles interact with the first block of each pair, projectile fragments are created which interact with other nuclei in the first and second blocks. What is measured is the ratio of some target fragment activity, such as 24 Na or 28 Mg, produced in the second block relative to the first block, R

Relativistic impulse dynamics.

Science.gov (United States)

Swanson, Stanley M

2011-08-01

Classical electrodynamics has some annoying rough edges. The self-energy of charges is infinite without a cutoff. The calculation of relativistic trajectories is difficult because of retardation and an average radiation reaction term. By reconceptuallizing electrodynamics in terms of exchanges of impulses rather than describing it by forces and potentials, we eliminate these problems. A fully relativistic theory using photonlike null impulses is developed. Numerical calculations for a two-body, one-impulse-in-transit model are discussed. A simple relationship between center-of-mass scattering angle and angular momentum was found. It reproduces the Rutherford cross section at low velocities and agrees with the leading term of relativistic distinguishable-particle quantum cross sections (Møller, Mott) when the distance of closest approach is larger than the Compton wavelength of the particle. Magnetism emerges as a consequence of viewing retarded and advanced interactions from the vantage point of an instantaneous radius vector. Radiation reaction becomes the local conservation of energy-momentum between the radiating particle and the emitted impulse. A net action is defined that could be used in developing quantum dynamics without potentials. A reinterpretation of Newton's laws extends them to relativistic motion.

Spinning relativistic particles in external fields

International Nuclear Information System (INIS)

Pomeranskii, Andrei A; Sen'kov, Roman A; Khriplovich, Iosif B

2000-01-01

The motion of spinning relativistic particles in external electromagnetic and gravitational fields is considered. The self-consistent equations of motion are built with the noncovariant description of spin and with the usual, 'naive' definition of the coordinate of a relativistic particle. A simple derivation of the gravitational interaction of first order in spin is presented for a relativistic particle. The approach developed allows one to consider effects of higher order in spin. Concrete calculations are performed for the second order. The gravimagnetic moment is discussed, a special spin effect in general relativity. We also consider the contributions of the spin interactions of first and second order to the gravitational radiation of compact binary stars. (from the current literature)

Electron correlation within the relativistic no-pair approximation

Energy Technology Data Exchange (ETDEWEB)

Almoukhalalati, Adel; Saue, Trond, E-mail: trond.saue@irsamc.ups-tlse.fr [Laboratoire de Chimie et Physique Quantique, UMR 5626 CNRS — Université Toulouse III-Paul Sabatier, 118 route de Narbonne, F-31062 Toulouse (France); Knecht, Stefan [ETH Zürich, Laboratorium für Physikalische Chemie, Vladimir-Prelog-Weg 2, 8093 Zürich (Switzerland); Jensen, Hans Jørgen Aa. [Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, DK-5230 Odense M (Denmark); Dyall, Kenneth G. [Dirac Solutions, 10527 NW Lost Park Drive, Portland, Oregon 97229 (United States)

2016-08-21

This paper addresses the definition of correlation energy within 4-component relativistic atomic and molecular calculations. In the nonrelativistic domain the correlation energy is defined as the difference between the exact eigenvalue of the electronic Hamiltonian and the Hartree-Fock energy. In practice, what is reported is the basis set correlation energy, where the “exact” value is provided by a full Configuration Interaction (CI) calculation with some specified one-particle basis. The extension of this definition to the relativistic domain is not straightforward since the corresponding electronic Hamiltonian, the Dirac-Coulomb Hamiltonian, has no bound solutions. Present-day relativistic calculations are carried out within the no-pair approximation, where the Dirac-Coulomb Hamiltonian is embedded by projectors eliminating the troublesome negative-energy solutions. Hartree-Fock calculations are carried out with the implicit use of such projectors and only positive-energy orbitals are retained at the correlated level, meaning that the Hartree-Fock projectors are frozen at the correlated level. We argue that the projection operators should be optimized also at the correlated level and that this is possible by full Multiconfigurational Self-Consistent Field (MCSCF) calculations, that is, MCSCF calculations using a no-pair full CI expansion, but including orbital relaxation from the negative-energy orbitals. We show by variational perturbation theory that the MCSCF correlation energy is a pure MP2-like correlation expression, whereas the corresponding CI correlation energy contains an additional relaxation term. We explore numerically our theoretical analysis by carrying out variational and perturbative calculations on the two-electron rare gas atoms with specially tailored basis sets. In particular, we show that the correlation energy obtained by the suggested MCSCF procedure is smaller than the no-pair full CI correlation energy, in accordance with the

Plasma relativistic microwave electronics

International Nuclear Information System (INIS)

Kuzelev, M.V.; Loza, O.T.; Rukhadze, A.A.; Strelkov, P.S.; Shkvarunets, A.G.

2001-01-01

One formulated the principles of plasma relativistic microwave electronics based on the induced Cherenkov radiation of electromagnetic waves at interaction of a relativistic electron beam with plasma. One developed the theory of plasma relativistic generators and accelerators of microwave radiation, designed and studied the prototypes of such devices. One studied theoretically the mechanisms of radiation, calculated the efficiencies and the frequency spectra of plasma relativistic microwave generators and accelerators. The theory findings are proved by the experiment: intensity of the designed sources of microwave radiation is equal to 500 μW, the frequency of microwave radiation is increased by 7 times (from 4 up to 28 GHz), the width of radiation frequency band may vary from several up to 100%. The designed sources of microwave radiation are no else compared in the electronics [ru

Relativistic electron mirrors from high intensity laser nanofoil interactions

Energy Technology Data Exchange (ETDEWEB)

Kiefer, Daniel

2012-12-21

The reflection of a laser pulse from a mirror moving close to the speed of light could in principle create an X-ray pulse with unprecedented high brightness owing to the increase in photon energy and accompanying temporal compression by a factor of 4γ{sup 2}, where γ is the Lorentz factor of the mirror. While this scheme is theoretically intriguingly simple and was first discussed by A. Einstein more than a century ago, the generation of a relativistic structure which acts as a mirror is demanding in many different aspects. Recently, the interaction of a high intensity laser pulse with a nanometer thin foil has raised great interest as it promises the creation of a dense, attosecond short, relativistic electron bunch capable of forming a mirror structure that scatters counter-propagating light coherently and shifts its frequency to higher photon energies. However, so far, this novel concept has been discussed only in theoretical studies using highly idealized interaction parameters. This thesis investigates the generation of a relativistic electron mirror from a nanometer foil with current state-of-the-art high intensity laser pulses and demonstrates for the first time the reflection from those structures in an experiment. To achieve this result, the electron acceleration from high intensity laser nanometer foil interactions was studied in a series of experiments using three inherently different high power laser systems and free-standing foils as thin as 3nm. A drastic increase in the electron energies was observed when reducing the target thickness from the micrometer to the nanometer scale. Quasi-monoenergetic electron beams were measured for the first time from ultrathin (≤5nm) foils, reaching energies up to ∝35MeV. The acceleration process was studied in simulations well-adapted to the experiments, indicating the transition from plasma to free electron dynamics as the target thickness is reduced to the few nanometer range. The experience gained from those

Interaction of relativistic elementary atoms with matter. I. General formulas

International Nuclear Information System (INIS)

Mrowczyn'ski, S.

1987-01-01

The problem of the interaction of relativistic elementary atoms (Coulomb bound states of elementary particles such as positronium, pionium, etc.) with matter is studied in the reference frame where the atom is initially at rest. An atom of matter is treated as a spinless structureless fast particle. The amplitudes of elementary-atom interaction are derived in the Born approximation under the assumption that a momentum transfer to the atom does not significantly exceed an inverse Bohr radius of the atom. The elementary-atom excitation and ionization processes are considered. The transitions where the spin projection of the atom component is reversed are also studied. In particular the matrix elements for para-ortho and ortho-para transitions are given. The spin structure of the amplitudes is discussed in detail. The sum rules, which allow the calculation of the cross sections summed over atom final states are found. Finally the formulas of the atom interaction cross sections are presented

Non-orthogonal configuration interaction for the calculation of multielectron excited states

Energy Technology Data Exchange (ETDEWEB)

Sundstrom, Eric J., E-mail: eric.jon.sundstrom@berkeley.edu; Head-Gordon, Martin [Department of Chemistry, University of California Berkeley, Berkeley, California 94720, USA and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2014-03-21

We apply Non-orthogonal Configuration Interaction (NOCI) to molecular systems where multielectron excitations, in this case double excitations, play a substantial role: the linear polyenes and β-carotene. We demonstrate that NOCI when applied to systems with extended conjugation, provides a qualitatively correct wavefunction at a fraction of the cost of many other multireference treatments. We also present a new extension to this method allowing for purification of higher-order spin states by utilizing Generalized Hartree-Fock Slater determinants and the details for computing 〈S{sup 2}〉 for the ground and excited states.

Isolating relativistic effects in large-scale structure

Science.gov (United States)

Bonvin, Camille

2014-12-01

We present a fully relativistic calculation of the observed galaxy number counts in the linear regime. We show that besides the density fluctuations and redshift-space distortions, various relativistic effects contribute to observations at large scales. These effects all have the same physical origin: they result from the fact that our coordinate system, namely the galaxy redshift and the incoming photons’ direction, is distorted by inhomogeneities in our Universe. We then discuss the impact of the relativistic effects on the angular power spectrum and on the two-point correlation function in configuration space. We show that the latter is very well adapted to isolate the relativistic effects since it naturally makes use of the symmetries of the different contributions. In particular, we discuss how the Doppler effect and the gravitational redshift distortions can be isolated by looking for a dipole in the cross-correlation function between a bright and a faint population of galaxies.

Industrial requirements for interactive product configurators

DEFF Research Database (Denmark)

Queva, Matthieu Stéphane Benoit; Probst, Christian W.; Vikkelsøe, Per

2009-01-01

The demand for highly customized products at low cost is driving the industry towards Mass Customization. Interactive product configurators play an essential role in this new trend, and must be able to support more and more complex features. The purpose of this paper is, firstly, to identify...... requirements for modern interactive configurators. Existing modeling and solving technologies for configuration are then reviewed and their limitations discussed. Finally, a proposition for a future product configuration system is described....

Attractive versus repulsive interactions in the Bose-Einstein condensation dynamics of relativistic field theories

Science.gov (United States)

Berges, J.; Boguslavski, K.; Chatrchyan, A.; Jaeckel, J.

2017-10-01

We study the impact of attractive self-interactions on the nonequilibrium dynamics of relativistic quantum fields with large occupancies at low momenta. Our primary focus is on Bose-Einstein condensation and nonthermal fixed points in such systems. For a model system, we consider O (N ) -symmetric scalar field theories. We use classical-statistical real-time simulations as well as a systematic 1 /N expansion of the quantum (two-particle-irreducible) effective action to next-to-leading order. When the mean self-interactions are repulsive, condensation occurs as a consequence of a universal inverse particle cascade to the zero-momentum mode with self-similar scaling behavior. For attractive mean self-interactions, the inverse cascade is absent, and the particle annihilation rate is enhanced compared to the repulsive case, which counteracts the formation of coherent field configurations. For N ≥2 , the presence of a nonvanishing conserved charge can suppress number-changing processes and lead to the formation of stable localized charge clumps, i.e., Q balls.

Matrix elements of the relativistic electron-transition operators

International Nuclear Information System (INIS)

Rudzikas, Z.B.; Slepcov, A.A.; Kickin, I.S.

1976-01-01

The formulas, which enable us to calculate the electric and magnetic multipole transition probabilities in relativistic approximation under various gauge conditions of the electromagnetic potential, are presented. The numerical values of the coefficients of the one-electron reduced matrix elements of the relativistic operators of the electric and magnetic dipole transitions between the configurations K 0 n 2 l 2 j 2 α 0 J 0 j 2 J--K 0 n 1 l 1 j 1 α 0 'J 0 'j 1 J', where K 0 represents any electronic configuration, having the quantum number of the total angular momentum 0 less than or equal to J 0 less than or equal to 8 (the step is 1 / 2 ), and 1 / 2 less than or equal to j 2 , j 1 less than or equal to 7 / 2 , are given

Electroweak interactions in a relativistic Fermi gas

International Nuclear Information System (INIS)

Vantournhout, K.; Jachowicz, N.; Ryckebusch, J.

2006-01-01

We present a relativistic model for computing the neutrino mean free path in neutron matter. In this model, neutron matter is described as a noninteracting Fermi gas in β equilibrium. We present results for the neutrino mean free path for temperatures of 0 to 50 MeV and a broad range of neutrino energies. We show that relativistic effects cause a considerable enhancement of neutrino-scattering cross sections in neutron matter. The influence of the Q 2 dependence in the electroweak form factors and the inclusion of a weak-magnetic term in the hadron current is discussed. The weak-magnetic term in the hadron current is at the origin of some selective spin dependence for the nucleons that are subject to neutrino interactions

On the relativistic quantum mechanics of two interacting spinless particles

International Nuclear Information System (INIS)

Rizov, V.A.; Sazdjian, H.; Todorov, I.T.

1984-05-01

The L 2 -scalar product ∫ PHI*(x)PSI(x) d 3 x is not appropriate for the space of states describing the center-of-mass relative motion of two relativistic particles whose interaction is given by an energy dependent quasipotential. The problem already appears in the relativistic quantum mechanics of a Klein-Gordon charged particle in an external field. We extend the methods developed for that case to study a two-particle system with an energy independent scalar interaction as well as the relativistic Coulomb problem. We write down a Poincare invariant inner product for which the eigenfunctions corresponding to different energy eigenvalues are orthogonal. We also construct a perturbative expansion for bound-state energy eigenvalues corresponding to an arbitrary energy dependent (quasipotential) correction to an unperturbed Hamiltonian with a known spectrum. The description of observables and transition probabilities for eigenvalue problems with a polynomial dependence on the spectral parameter is also discussed

Symmetry-adapted-cluster configuration-interaction and equation-of-motion coupled-cluster studies of electronically excited states of copper tetrachloride and copper tetrabromide dianions

International Nuclear Information System (INIS)

Ehara, Masahiro; Piecuch, Piotr; Lutz, Jesse J.; Gour, Jeffrey R.

2012-01-01

Graphical abstract: Electronically excited states of CuCl 4 2- and CuBr 4 2- are determined using the scalar relativistic symmetry-adapted-cluster configuration-interaction and equation-of-motion coupled-cluster calculations. The results are compared with experimental spectra. Highlights: ► Electronic spectra of CuCl 4 2- and CuBr 4 2- are examined by SAC-CI and EOMCC methods. ► Relativistic SAC-CI and EOMCC results are compared with experimental spectra. ► An assignment of bands in the CuCl 4 2- and CuBr 4 2- absorption spectra is obtained. ► Relativistic effects affect excitation energies and ground-state geometries. ► The effect of relativity on the oscillator strengths is generally small. - Abstract: The valence excitation spectra of the copper tetrachloride and copper tetrabromide open-shell dianions, CuCl 4 2- and CuBr 4 2- , respectively, are investigated by a variety of symmetry-adapted-cluster configuration-interaction (SAC-CI) and equation-of-motion coupled-cluster (EOMCC) methods. The valence excited states of the CuCl 4 2- and CuBr 4 2- species that correspond to transitions from doubly occupied molecular orbitals (MOs) to a singly occupied MO (SOMO), for which experimental spectra are available, are examined with the ionized (IP) variants of the SAC-CI and EOMCC methods. The higher-energy excited states of CuCl 4 2- and CuBr 4 2- that correspond to transitions from SOMO to unoccupied MOs, which have not been characterized experimentally, are determined using the electron-attached (EA) SAC-CI and EOMCC approaches. An emphasis is placed on the scalar relativistic SAC-CI and EOMCC calculations based on the spin-free part of the second-order Douglass–Kroll–Hess Hamiltonian (DKH2) and on a comparison of the results of the IP and EA SAC-CI and EOMCC calculations with up to 2-hole-1-particle (2h-1p) and 2-particle-1-hole (2p-1h) excitations, referred to as the IP-SAC-CI SD-R and IP-EOMCCSD(2h-1p) methods in the IP case and EA-SAC-CI SD-R and EA

Relativistic rapprochement of electromagnetic and strong interactions

International Nuclear Information System (INIS)

Strel'tsov, V.N.

1995-01-01

On the basis of the Lienard-Wiechert potential and the relativistic Yukawa potential it is shown that the corresponding interactions with velocity growth increase differently (the electromagnetic one increases faster). According to preliminary estimations they are equivalent, at distances of the 'action radius' of nuclear forces, at γ≅ 960, where γ is the Lorentz factor. 2 refs

Description of width and spectra of two relativistic fermions bound states

International Nuclear Information System (INIS)

Sidorov, A.V.; Skachkov, N.B.

1979-01-01

The formalism for relativistic description of two particles with spin 1/2 is constructed. Used is the two-particle three-dimensional equation, obtained by quasipotential approach. Quasipotential equation in the relativistic configurational space with OBEP potential is reduced to the system of partial equations which is the analog of nonrelativistic Hamada-Jonston system. WKB approach is used to calculate mass spectra and leptonic width of mesons in quark model. The results of the study can be applied to the calculation of mass spectra and widths of electromagnetic decays of systems of e + e - , μ + μ - , c anti c, b anti b, N anti N type

New analytically solvable models of relativistic point interactions

International Nuclear Information System (INIS)

Gesztesy, F.; Seba, P.

1987-01-01

Two new analytically solvable models of relativistic point interactions in one dimension (being natural extensions of the nonrelativistic δ-resp, δ'-interaction) are considered. Their spectral properties in the case of finitely many point interactions as well as in the periodic case are fully analyzed. Moreover the spectrum is explicitely determined in the case of independent, identically distributed random coupling constants and the analog of the Saxon and Huther conjecture concerning gaps in the energy spectrum of such systems is derived

Term structure of 4d-electron configurations and calculated spectrum in Sn-isonuclear sequence

International Nuclear Information System (INIS)

Al-Rabban, Moza M.

2006-01-01

Theoretical calculations of term structure are carried out for the ground configurations 4d w , of atomic ions in the Sn isonuclear sequence. Atomic computations are performed to give a detailed account of the transitions in Sn +6 to Sn +13 ions. The spectrum is calculated for the most important excited configurations 4p 5 4d n+1 , 4d n-1 4f 1 , and 4d n-1 5p 1 with respect to the ground configuration 4d n , with n=8-1, respectively. The importance of 4p-4d, 4d-4f, and 4d-5p transitions is stressed, as well as the need for the configuration-interaction CI treatment of the Δn=0 transitions. In the region of importance for extreme ultraviolet (EUV) lithography around 13.4nm, the strongest lines were expected to be 4d n -4p 5 4d n+1 and 4d n -4d n-1 4f 1

Report of seminar on relativistic approach to nuclear reaction and nuclear structure

International Nuclear Information System (INIS)

1986-05-01

A seminar on 'Relativistic Approach to Nuclear Reaction and Nuclear Structure' was held in 1985 at Osaka University. This booklet includes twenty-four reports given at the seminar, which deal with: Conventional Nonrelativistic Description of Nuclear Matter and Nuclear Spin-Orbit Interactions; Relativistic Approach to Nuclear Structure; Atomic and Molecular Structure Calculations; Electromagnetic Interaction in Nucleus and Relativistic Effect; Nuclear Magnetic Moment in the Relativistic Mean Field Theory, Effective Mass and Particle-Vibration Coupling in the Relativistic σ-ω Model; Gauge Invariance in Relativistic Many-Body Theory; Relativistic Description of Nucleon-Nucleon Interaction in Review; σ-Particle in NN Interaction; Nuclear Optical Potentials Based on the Brueckner-Hartree-Fock Approach; Elastic Backscattering and Optical Potential; Description of Intermediate-Energy Nuclear Reactions; Dirac Phenomenology at E(p) = 65 MeV; Relativistic Impulse Approximation; Reaction Studies with Intermediate Energy Deuterons at SATURNE; Folding Model for Intermediate-Energy Deutron Scattering; Folding Model for Polarized Deutron Scattering at 700 MeV; Dirac Approach Problems and a Different Viewpoint; Relativistic Approach and EMC Effect; Quasielastic Electron Scattering; Response Function of Quasielastic Electron Scattering; Relativistic Hartree Response Function for Quasielastic Electron Scattering on 12 C and 40 Ca; Backflow-, Retardation- and Relativistic Effects on the Longitudinal Response Function of Nuclear Matter; Pion-Photoproduction in the σ-ω Model. (Nogami, K.)

Calculation of Configurational Entropy in Complex Landscapes

Directory of Open Access Journals (Sweden)

Samuel A Cushman

2018-04-01

Full Text Available Entropy and the second law of thermodynamics are fundamental concepts that underlie all natural processes and patterns. Recent research has shown how the entropy of a landscape mosaic can be calculated using the Boltzmann equation, with the entropy of a lattice mosaic equal to the logarithm of the number of ways a lattice with a given dimensionality and number of classes can be arranged to produce the same total amount of edge between cells of different classes. However, that work seemed to also suggest that the feasibility of applying this method to real landscapes was limited due to intractably large numbers of possible arrangements of raster cells in large landscapes. Here I extend that work by showing that: (1 the proportion of arrangements rather than the number with a given amount of edge length provides a means to calculate unbiased relative configurational entropy, obviating the need to compute all possible configurations of a landscape lattice; (2 the edge lengths of randomized landscape mosaics are normally distributed, following the central limit theorem; and (3 given this normal distribution it is possible to fit parametric probability density functions to estimate the expected proportion of randomized configurations that have any given edge length, enabling the calculation of configurational entropy on any landscape regardless of size or number of classes. I evaluate the boundary limits (4 for this normal approximation for small landscapes with a small proportion of a minority class and show it holds under all realistic landscape conditions. I further (5 demonstrate that this relationship holds for a sample of real landscapes that vary in size, patch richness, and evenness of area in each cover type, and (6 I show that the mean and standard deviation of the normally distributed edge lengths can be predicted nearly perfectly as a function of the size, patch richness and diversity of a landscape. Finally, (7 I show that the

Relativistic effects in the intermolecular interaction-induced nuclear magnetic resonance parameters of xenon dimer.

Science.gov (United States)

Hanni, Matti; Lantto, Perttu; Ilias, Miroslav; Jensen, Hans Jorgen Aagaard; Vaara, Juha

2007-10-28

Relativistic effects on the (129)Xe nuclear magnetic resonance shielding and (131)Xe nuclear quadrupole coupling (NQC) tensors are examined in the weakly bound Xe(2) system at different levels of theory including the relativistic four-component Dirac-Hartree-Fock (DHF) method. The intermolecular interaction-induced binary chemical shift delta, the anisotropy of the shielding tensor Deltasigma, and the NQC constant along the internuclear axis chi( parallel) are calculated as a function of the internuclear distance. DHF shielding calculations are carried out using gauge-including atomic orbitals. For comparison, the full leading-order one-electron Breit-Pauli perturbation theory (BPPT) is applied using a common gauge origin. Electron correlation effects are studied at the nonrelativistic (NR) coupled-cluster singles and doubles with perturbational triples [CCSD(T)] level of theory. The fully relativistic second-order Moller-Plesset many-body perturbation (DMP2) theory is used to examine the cross coupling between correlation and relativity on NQC. The same is investigated for delta and Deltasigma by BPPT with a density functional theory model. A semiquantitative agreement between the BPPT and DHF binary property curves is obtained for delta and Deltasigma in Xe(2). For these properties, the currently most complete theoretical description is obtained by a piecewise approximation where the uncorrelated relativistic DHF results obtained close to the basis-set limit are corrected, on the one hand, for NR correlation effects and, on the other hand, for the BPPT-based cross coupling of relativity and correlation. For chi( parallel), the fully relativistic DMP2 results obtain a correction for NR correlation effects beyond MP2. The computed temperature dependence of the second virial coefficient of the (129)Xe nuclear shielding is compared to experiment in Xe gas. Our best results, obtained with the piecewise approximation for the binary chemical shift combined with the

Relativistic many-body bound systems. Monograph report

International Nuclear Information System (INIS)

Danos, M.; Gillet, V.

1975-04-01

The principles and the mathematical details of a fully relativistic nuclear theory are given. Since the concept of nuclear forces is a strictly non-relativistic construct, it must be abandoned, and the forces must be replaced explicitly by their physical origin, i.e., by the interaction between nucleons and mesons. Thus, in this monograph the description of a nucleus has been formulated as a problem of relativistic quantum field theory which is solved by nuclear physics methods; to wit: the physics is described by specifying a Lagrangian which is a functional of the constituent fields (= of the parton fields); the solutions for the physical systems then are obtained in a time-independent treatment as expansions in the parton fields: both particles and nuclei are composite systems, made up of parton configurations, which define a representation of the Hamiltonian (associated with the specified Lagrangian)

Differential regularization of a non-relativistic anyon model

International Nuclear Information System (INIS)

Freedman, D.Z.; Rius, N.

1993-07-01

Differential regularization is applied to a field theory of a non-relativistic charged boson field φ with λ(φ * φ) 2 self-interaction and coupling to a statistics-changing 0(1) Chern-Simons gauge field. Renormalized configuration-space amplitudes for all diagrams contributing to the φ * φ * φφ 4-point function, which is the only primitively divergent Green's function, are obtained up to 3-loop order. The renormalization group equations are explicitly checked, and the scheme dependence of the β-function is investigated. If the renormalization scheme is fixed to agree with a previous 1-loop calculation, the 2- and 3-loop contributions to β(λ, e) vanish, and β(λ, ε) itself vanishes when the ''self-dual'' condition relating λ to the gauge coupling e is imposed. (author). 12 refs, 1 fig

Relativistic effects in iron-, ruthenium-, and osmium porphyrins

International Nuclear Information System (INIS)

Liao Mengsheng; Scheiner, Steve

2002-01-01

Nonrelativistic and relativistic DFT calculations are performed on four-coordinate metal porphyrins MP and their six-coordinate adducts MP(py) 2 and MP(py)(CO) (py=pyridine) with M=Fe, Ru, and Os. The electronic structures of the MPs are investigated by considering all possible low-lying states with different configurations of nd-electrons. FeP and OsP have a 3 A 2g ground state, while this state is nearly degenerate with 3 E g for RuP. Without relativistic corrections, the ground states of both RuP and OsP would be 3 E g . For the six-coordinate adducts with py and CO, the strong-field axial ligands raise the energy of the M d z 2 -orbital, thereby making the M II ion diamagnetic. The calculated redox properties of MP(py) 2 and MP(py)(CO) are in agreement with experiment. The difference between RuP(py)(CO) and OsP(py)(CO), in terms of site of oxidation, is due to relativistic effects

Using full configuration interaction quantum Monte Carlo in a seniority zero space to investigate the correlation energy equivalence of pair coupled cluster doubles and doubly occupied configuration interaction

International Nuclear Information System (INIS)

Shepherd, James J.; Henderson, Thomas M.; Scuseria, Gustavo E.

2016-01-01

Over the past few years, pair coupled cluster doubles (pCCD) has shown promise for the description of strong correlation. This promise is related to its apparent ability to match results from doubly occupied configuration interaction (DOCI), even though the latter method has exponential computational cost. Here, by modifying the full configuration interaction quantum Monte Carlo algorithm to sample only the seniority zero sector of Hilbert space, we show that the DOCI and pCCD energies are in agreement for a variety of 2D Hubbard models, including for systems well out of reach for conventional configuration interaction algorithms. Our calculations are aided by the sign problem being much reduced in the seniority zero space compared with the full space. We present evidence for this and then discuss the sign problem in terms of the wave function of the system which appears to have a simplified sign structure.

Configurational energies and effective cluster interactions in substitutionally disordered binary alloys

International Nuclear Information System (INIS)

Gonis, A.; Zhang, X.h.; Freeman, A.J.; Turchi, P.; Stocks, G.M.; Nicholson, D.M.

1987-01-01

The determination of configurational energies in terms of effective cluster interactions in substitutionally disordered alloys from a knowledge of the alloy electronic structure is examined within the methods of concentration waves (CW) and the generalized perturbation method (GPM), and for the first time within the embedded-cluster method (ECM). It is shown that the ECM provides the exact summation to all orders of the effective cluster interaction expansions obtained in the partially renormalized GPM. The connection between the various methods (CW, GPM, and ECM) is discussed and illustrated by means of numerical calculations for model one-dimensional tight-binding (TB) systems and for TB Hamiltonians chosen to describe Pd-V alloys. These calculations, and the formal considerations presented in the body of the paper, show the complete equivalence of converged GPM summations within specific clusters and the ECM. In addition, it is shown that an exact expansion of the configurational energy can be obtained in terms of fully renormalized effective cluster interactions. In principle, these effective cluster interactions can be used in conjunction with statistical models to determine stable ordered structures at low temperatures and alloy phase diagrams

Calculation of fusion gain in fast ignition with magnetic target by relativistic electrons and protons

International Nuclear Information System (INIS)

Parvazian, A.; Javani, A.

2010-01-01

Fast ignition is a new method for inertial confinement fusion in which the compression and ignition steps are separated. In the first stage, fuel is compressed by laser or ion beams. In the second phase, relativistic electrons are generated by pettawat laser in the fuel. Also, in the second phase 5-35 MeV protons can be generated in the fuel. Electrons or protons can penetrate in to the ultra-dense fuel and deposit their energy in the fuel. More recently, cylindrical rather than spherical fuel chambers with magnetic control in the plasma domain have been also considered. This is called magnetized target fusion. Magnetic field has effects on relativistic electrons energy deposition rate in fuel. In this work, fast ignition method in cylindrical fuel chambers is investigated and transportation of the relativistic electrons and protons is calculated using MCNPX and FLUKA codes with 0.25 and 0.5 tesla magnetic field in single and dual hot spot. Furthermore, the transfer rate of relativistic electrons and high energy protons to the fuel and fusion gain are calculated. The results show that the presence of external magnetic field guarantees higher fusion gain, and relativistic electrons are much more appropriate objects for ignition. Magnetized target fusion in dual hot spot can be considered as an appropriate substitution for the current inertial confinement fusion techniques.

Calculation of fusion gain in fast ignition with magnetic target by relativistic electrons and protons

Directory of Open Access Journals (Sweden)

A Parvazian

2010-12-01

Full Text Available Fast ignition is a new method for inertial confinement fusion (ICF in which the compression and ignition steps are separated. In the first stage, fuel is compressed by laser or ion beams. In the second phase, relativistic electrons are generated by pettawat laser in the fuel. Also, in the second phase 5-35 MeV protons can be generated in the fuel. Electrons or protons can penetrate in to the ultra-dense fuel and deposit their energy in the fuel . More recently, cylindrical rather than spherical fuel chambers with magnetic control in the plasma domain have been also considered. This is called magnetized target fusion (MTF. Magnetic field has effects on relativistic electrons energy deposition rate in fuel. In this work, fast ignition method in cylindrical fuel chambers is investigated and transportation of the relativistic electrons and protons is calculated using MCNPX and FLUKA codes with 0. 25 and 0. 5 tesla magnetic field in single and dual hot spot. Furthermore, the transfer rate of relativistic electrons and high energy protons to the fuel and fusion gain are calculated. The results show that the presence of external magnetic field guarantees higher fusion gain, and relativistic electrons are much more appropriate objects for ignition. MTF in dual hot spot can be considered as an appropriate substitution for the current ICF techniques.

GRASP92: a package for large-scale relativistic atomic structure calculations

Science.gov (United States)

Parpia, F. A.; Froese Fischer, C.; Grant, I. P.

2006-12-01

of CSFs sharing the same quantum numbers is determined using the configuration-interaction (CI) procedure that results upon varying the expansion coefficients to determine the extremum of a variational functional. Radial functions may be determined by numerically solving the multiconfiguration Dirac-Fock (MCDF) equations that result upon varying the orbital radial functions or some subset thereof so as to obtain an extremum of the variational functional. Radial wavefunctions may also be determined using a screened hydrogenic or Thomas-Fermi model, although these schemes generally provide initial estimates for MCDF self-consistent-field (SCF) calculations. Transition properties for pairs of ASFs are computed from matrix elements of multipole operators of the electromagnetic field. All matrix elements of CSFs are evaluated using the Racah algebra. Reasons for the new version: During recent studies using the general relativistic atomic structure package (GRASP92), several errors were found, some of which might have been present already in the earlier GRASP92 version (program ABJN_v1_0, Comput. Phys. Comm. 55 (1989) 425). These errors were reported and discussed by Froese Fischer, Gaigalas, and Ralchenko in a separate publication [C. Froese Fischer, G. Gaigalas, Y. Ralchenko, Comput. Phys. Comm. 175 (2006) 738-744. [7

Calculation of helium-like ion dipole susceptibility with account for electron interaction

International Nuclear Information System (INIS)

Pal'chikov, V.G.; Tkachev, A.N.

1989-01-01

Numerical estimations of electron interaction effects are carried out for helium-like ions inserted in a homogeneous electric field. Statistical dipole polarizations and hyperpolarizations are calculated for the main state taking into account corrections of the first order to approximation of noninteracting electrons. Summation according to the full spectrum of intermediate states is carried out by the method of Coulomb-Green functions (CGF), that permitted to use analytical methods to calculate matrix elements of correlation diagrams. When calculating polarizations, relativistic corrections ∼(αZ) 2 , where α - the constant of a fine structure, Z-nucleus charge, are taken into account

Relativistic stars with purely toroidal magnetic fields

International Nuclear Information System (INIS)

Kiuchi, Kenta; Yoshida, Shijun

2008-01-01

We investigate the effects of the purely toroidal magnetic field on the equilibrium structures of the relativistic stars. The basic equations for obtaining equilibrium solutions of relativistic rotating stars containing purely toroidal magnetic fields are derived for the first time. To solve these basic equations numerically, we extend the Cook-Shapiro-Teukolsky scheme for calculating relativistic rotating stars containing no magnetic field to incorporate the effects of the purely toroidal magnetic fields. By using the numerical scheme, we then calculate a large number of the equilibrium configurations for a particular distribution of the magnetic field in order to explore the equilibrium properties. We also construct the equilibrium sequences of the constant baryon mass and/or the constant magnetic flux, which model the evolution of an isolated neutron star as it loses angular momentum via the gravitational waves. Important properties of the equilibrium configurations of the magnetized stars obtained in this study are summarized as follows: (1) For the nonrotating stars, the matter distribution of the stars is prolately distorted due to the toroidal magnetic fields. (2) For the rapidly rotating stars, the shape of the stellar surface becomes oblate because of the centrifugal force. But, the matter distribution deep inside the star is sufficiently prolate for the mean matter distribution of the star to be prolate. (3) The stronger toroidal magnetic fields lead to the mass shedding of the stars at the lower angular velocity. (4) For some equilibrium sequences of the constant baryon mass and magnetic flux, the stars can spin up as they lose angular momentum.

Electric dipole moment of diatomic molecules by configuration interaction. IV.

Science.gov (United States)

Green, S.

1972-01-01

The theory of basis set dependence in configuration interaction calculations is discussed, taking into account a perturbation model which is valid for small changes in the self-consistent field orbitals. It is found that basis set corrections are essentially additive through first order. It is shown that an error found in a previously published dipole moment calculation by Green (1972) for the metastable first excited state of CO was indeed due to an inadequate basis set as claimed.

Ab initio calculation of diffusion barriers for Cu adatom hopping on Cu(1 0 0) surface and evolution of atomic configurations

Science.gov (United States)

Zhang, Wei; Gan, Jie; Li, Qian; Gao, Kun; Sun, Jian; Xu, Ning; Ying, Zhifeng; Wu, Jiada

2011-06-01

The self-diffusion dynamics of Cu adatoms on Cu(1 0 0) surface has been studied based on the calculation of the energy barriers for various hopping events using lattice-gas based approach and a modified model. To simplify the description of the interactions and the calculation of the energy barrier, a three-tier hierarchy of description of atomic configurations was conceived in which the active adatom and its nearest atoms were chosen to constitute basic configuration and taken as a whole to study many-body interactions of the atoms in various atomic configurations, whereas the impacts of the next nearest atoms on the diffusion of the active adatom were considered as multi-site interactions. Besides the simple hopping of single adatoms, the movements of dimers and trimers as the results of multiple hopping events have also been examined. Taking into account the hopping events of all adatoms, the stability of atomic configurations has been examined and the evolution of atomic configurations has also been analyzed.

Ab initio calculation of diffusion barriers for Cu adatom hopping on Cu(1 0 0) surface and evolution of atomic configurations

International Nuclear Information System (INIS)

Zhang Wei; Gan Jie; Li Qian; Gao Kun; Sun Jian; Xu Ning; Ying Zhifeng; Wu Jiada

2011-01-01

The self-diffusion dynamics of Cu adatoms on Cu(1 0 0) surface has been studied based on the calculation of the energy barriers for various hopping events using lattice-gas based approach and a modified model. To simplify the description of the interactions and the calculation of the energy barrier, a three-tier hierarchy of description of atomic configurations was conceived in which the active adatom and its nearest atoms were chosen to constitute basic configuration and taken as a whole to study many-body interactions of the atoms in various atomic configurations, whereas the impacts of the next nearest atoms on the diffusion of the active adatom were considered as multi-site interactions. Besides the simple hopping of single adatoms, the movements of dimers and trimers as the results of multiple hopping events have also been examined. Taking into account the hopping events of all adatoms, the stability of atomic configurations has been examined and the evolution of atomic configurations has also been analyzed.

Electromagnetic interactions in relativistic systems of many bodies

International Nuclear Information System (INIS)

Cook, A.H.

1987-09-01

In a previous report (Cook, 1986, 1987) on a formulation of a quasi-relativistic quantum mechanical equation of motion for many particles, little was said of the electromagnetic interactions that keep a set of particles in a bound state. That omission is to some extent repaired in this report. (author). 3 refs

Analytical calculations of intense Gaussian laser beam propagating in plasmas with relativistic collision correction

International Nuclear Information System (INIS)

Wang Ying; Yuan Chengxun; Gao Ruilin; Zhou Zhongxiang

2012-01-01

Theoretical investigations of a Gaussian laser beam propagating in relativistic plasmas have been performed with the WKB method and complex eikonal function. We consider the relativistic nonlinearity induced by intense laser beam, and present the relativistically generalized forms of the plasma frequency and electron collision frequency in plasmas. The coupled differential equations describing the propagation variations of laser beam are derived and numerically solved. The obtained simulation results present the similar variation tendency with experiments. By changing the plasma density, we theoretically analyze the feasibility of using a plasmas slab of a fixed thickness to compress the laser beam-width and acquire the focused laser intensity. The present work complements the relativistic correction of the electron collision frequency with reasonable derivations, promotes the theoretical approaching to experiments and provides effective instructions to the practical laser-plasma interactions.

Energy level properties of 4p64d3, 4p64d24f, and 4p54d4 configurations of the W35+ ion

International Nuclear Information System (INIS)

Bogdanovich, P.; Kisielius, R.

2014-01-01

The ab initio quasirelativistic Hartree–Fock method developed specifically for the calculation of spectroscopic parameters of heavy atoms and highly charged ions was used to derive spectral data for the multicharged tungsten ion W 35+ . The configuration interaction method was applied to include the electron-correlation effects. The relativistic effects were taken into account in the Breit–Pauli approximation for quasirelativistic Hartree–Fock radial orbitals. The energy level spectra, radiative lifetimes τ, and Lande g-factors have been calculated for the 4p 6 4d 3 , 4p 6 4d 2 4f, and 4p 5 4d 4 configurations of the W 35+ ion

Relativistic transition probabilities for F-like ions with 10 Z 49

International Nuclear Information System (INIS)

Santos, J.P.; Madruga, C.; Parente, F.; Indelicato, P.

2005-01-01

In the present work we have calculated several relativistic transition probabilities for the F-like ions with 10 Z 49, in the framework of the Multi-Configuration Dirac-Fock method, for applications on laserphysics and astrophysics. The lines considered correspond to transitions between levels of 2p 4 3s, 2p 4 3p and 2p 4 3d configurations. The spectral fine structure is taken into consideration and the results for individual lines are given

Higher-order resonant electronic recombination as a manifestation of configuration interaction

International Nuclear Information System (INIS)

Beilmann, C; Amaro, P; Tashenov, S; Bekker, H; Harman, Z; Crespo López-Urrutia, J R

2013-01-01

Theoretical and experimental investigations of higher-order electron–ion recombination resonances including inter-shell excitations are presented for L-shell ions of Kr with the aim of examining details of atomic structure calculations. The particular importance of electron–electron interaction and configuration mixing effects for these recombination processes enables their use for detailed tests of electron correlation effects. A test of the required level of considered mixing configurations is presented and further experiments involving higher-order recombination channels are motivated. (paper)

Interactive Cost Configuration Over Decision Diagrams

DEFF Research Database (Denmark)

Andersen, Henrik Reif; Hadzic, Tarik; Pisinger, David

2010-01-01

interaction online. In particular,binary decision diagrams (BDDs) have been successfully used as a compilation target for product and service configuration. In this paper we discuss how to extend BDD-based configuration to scenarios involving cost functions which express user preferences. We first show...... that an efficient, robust and easy to implement extension is possible if the cost function is additive, and feasible solutions are represented using multi-valued decision diagrams (MDDs). We also discuss the effect on MDD size if the cost function is non-additive or if it is encoded explicitly into MDD. We...... then discuss interactive configuration in the presence of multiple cost functions. We prove that even in its simplest form, multiple-cost configuration is NP-hard in the input MDD. However, for solving two-cost configuration we develop a pseudo-polynomial scheme and a fully polynomial approximation scheme...

Relativistic electron beam interaction with a thin target

International Nuclear Information System (INIS)

Gazaix, M.

1981-03-01

This study is concerned with the increasing possibilities of electron energy deposition in thin targets. The thesis theoretical part studies the relativistic electron beam-plasma instability; the Buneman-Pierce instability in limited medium is also studied. In the experimental part, several questions are tentatively answered: - what is the spatial and temporal evolution of the anode material, in temperature and in density. - What sort of interaction is the beam-target interaction; more particularly questions about focusing and energy deposition are studied [fr

Co-Configuration in Interaction Work

DEFF Research Database (Denmark)

Fischer, Louise Harder; Pries-Heje, Lene

2015-01-01

How to increase knowledge workers productivity is still a puzzle. While knowledge work has become increasingly virtual, collaborative and interactive, we still witness challenges in the area of productivity. We challenge the widespread perception of the causal relationship between high autonomy...... and high productivity in knowledge work and the fact that configuration and standardization for improving productivity is logical impossible. With a hermeneutical approach we describe and interpret “what is going on” in two different context of interaction knowledge work. Findings suggests that knowledge...... workers often feel caught in counter-productive practices with technology, due to the autonomous use of Interaction-IT and the challenge of configuring work. We witness different behaviors related to “the autonomy paradox” and we see something interesting happening, when introducing Interaction IT. While...

Relativistic two-fermion equations with form factors and anomalous magnetic moment interactions

International Nuclear Information System (INIS)

Ahmed, S.

1977-04-01

Relativistic equations for two-fermion systems are derived from quantum field theory taking into account the form factors of the particles. When the q 2 dependence of the form factors is disregarded, in the static approximation, the two-fermion equations with Coulomb and anomalous magnetic moment interactions are obtained. Separating the angular variables, a sixteen-component relativistic radial equation are finally given

Calculation of high power relativistic beams with consideration of collision effects

International Nuclear Information System (INIS)

Sveshnikov, V.M.

1986-01-01

This paper considers the numerical calculation of relativistic charged particle beams moving in axisymmetric systems in which the presence of a residual neutral gas is possible. It is essential to consider phenomena related to collisions between charged particles and neutrals. Algorithms are constructed for numerical modeling of ionization processes within the framework of the ERA program complex. Solutions of model and practical problems are presented as examples. Such problems were studied where ionization processes were considered by a more complex method requiring a greater volume of calculations but valid at lower pressures

Treating Coulomb exchange contributions in relativistic mean field calculations: why and how

International Nuclear Information System (INIS)

Giai, Nguyen Van; Liang, Haozhao; Gu, Huai-Qiang; Long, Wenhui; Meng, Jie

2014-01-01

The energy density functional (EDF) method is very widely used in nuclear physics, and among the various existing functionals those based on the relativistic Hartree (RH) approximation are very popular because the exchange contributions (Fock terms) are numerically rather onerous to calculate. Although it is possible to somehow ‘mock up’ the effects of meson-induced exchange terms by adjusting the meson–nucleon couplings, the lack of Coulomb exchange contributions hampers the accuracy of predictions. In this work, we show that the Coulomb exchange effects can be easily included with good accuracy in a perturbative approach. Therefore, it would be desirable for future relativistic EDF models to incorporate Coulomb exchange effects, at least to some order of perturbation

Final-state interactions and superscaling in the semi-relativistic approach to quasielastic electron and neutrino scattering

International Nuclear Information System (INIS)

Amaro, J. E.; Barbaro, M. B.; Caballero, J. A.; Donnelly, T. W.; Udias, J. M.

2007-01-01

The semi-relativistic approach to electron and neutrino quasielastic scattering from nuclei is extended to include final-state interactions. Starting with the usual nonrelativistic continuum shell model, the problem is relativized by using the semi-relativistic expansion of the current in powers of the initial nucleon momentum and relativistic kinematics. Two different approaches are considered for the final-state interactions: the Smith-Wambach 2p-2h damping model and the Dirac-equation-based potential extracted from a relativistic mean-field plus the Darwin factor. Using the latter, the scaling properties of (e,e ' ) and (ν μ ,μ - ) cross sections for intermediate momentum transfers are investigated

Relativistic Calculations and Measurements of Energies, Auger Rates, and Lifetimes.

Science.gov (United States)

1982-12-01

Research and Industry, Denton, Texas, 8-10 November 1982. 7. B. Crasemann: "Efectos Relativ’sticos y de QED Sobre las Transiciones Rayos - X y Auger Entre...INNER-SHELL IONIZATION BY PROTONS X -RAY EMISSION BREIT INTERACTION AUGER TRANSITIONS DIRAC-HARTREE-SLATER COMPUTATIONS SYNCHROTRON RADIATION RESONANT...computations, including relativistic and quantum- electrodynamic effects, of atomic energy levels and of x -ray and Auger transitions in atoms with one or

An introduction to relativistic processes and the standard model of electroweak interactions

CERN Document Server

Becchi, Carlo Maria

2014-01-01

These lectures are meant to be a reference and handbook for an introductory course in Theoretical Particle Physics, suitable for advanced undergraduates or beginning graduate students. Their purpose is to reconcile theoretical rigour and completeness with a careful analysis of more phenomenological aspects of the physics. They aim at filling the gap between quantum field theory textbooks and purely phenomenological treatments of fundamental interactions. The first part provides an introduction to scattering in relativistic quantum field theory. Thanks to an original approach to relativistic processes, the relevant computational techniques are derived cleanly and simply in the semi-classical approximation. The second part contains a detailed presentation of the gauge theory of electroweak interactions with particular focus to the processes of greatest phenomenological interest. The main novelties of the present second edition are a more complete discussion of relativistic scattering theory and an expansion of ...

Multiconfiguration Dirac-Hartree-Fock calculations of energy levels and radiative rates of Fe VII

Science.gov (United States)

Li, Yang; Xu, Xiaokai; Li, Bowen; Jönsson, Per; Chen, Ximeng

2018-06-01

Detailed calculations are performed for 134 fine-structure levels of the 3p63d2, 3p63d4s, 3p53d3 and 3p63d4p configurations in Fe VII using the multiconfiguration Dirac-Hartree-Fock (MCDHF) and relativistic configuration interaction (RCI) methods. Important electron correlation effects are systematically accounted for through active space (AS) expansions. Our results compare well with experimental measurements, emphasizing the importance of a careful treatment of electron correlation, and provide some missing data in the NIST atomic database. The data obtained are expected to be useful in astrophysical applications, particularly for the research of the solar coronal plasma.

Relativistic effects on magnetic circular dichroism studied by GUHF/SECI method

Science.gov (United States)

Honda, Y.; Hada, M.; Ehara, M.; Nakatsuji, H.; Downing, J.; Michl, J.

2002-04-01

Quasi-relativistic formulation of the Magnetic circular dichroism (MCD) Faraday terms are presented using the generalized unrestricted Hartree-Fock (GUHF)/single excitation configuration interaction (SECI) method combined with the finite perturbation method and applied to the MCD of the three n-σ ∗ states ( 3Q1, 3Q0, 1Q1) of CH 3I. The Faraday B term for the 1Q1 state was 0.1976( Debye) 2( Bohr magneton )/(10 3 cm-1) in the non-relativistic theory, but was dramatically improved by the relativistic effect and became 0.0184 in agreement with the experimental values, 0.014 and 0.0257. This change was mainly due to the one-electron spin-orbit (SO1) term rather than the spin-free relativistic (SFR) and the two-electron spin-orbit (SO2) terms.

Relativistic deformed mean-field calculation of binding energy differences of mirror nuclei

International Nuclear Information System (INIS)

Koepf, W.; Barreiro, L.A.

1996-01-01

Binding energy differences of mirror nuclei for A=15, 17, 27, 29, 31, 33, 39 and 41 are calculated in the framework of relativistic deformed mean-field theory. The spatial components of the vector meson fields and the photon are fully taken into account in a self-consistent manner. The calculated binding energy differences are systematically smaller than the experimental values and lend support to the existence of the Okamoto-Nolen-Schiffer anomaly found decades ago in nonrelativistic calculations. For the majority of the nuclei studied, however, the results are such that the anomaly is significantly smaller than the one obtained within state-of-the-art nonrelativistic calculations. (author). 35 refs

Theoretical energy level spectra and transition data for 4p64d, 4p64f and 4p54d2 configurations of W37+ ion

International Nuclear Information System (INIS)

Bogdanovich, P.; Kisielius, R.

2012-01-01

The ab initio quasirelativistic Hartree–Fock method developed specifically for the calculation of spectral parameters of heavy atoms and highly charged ions was applied to determine atomic data for tungsten ions. The correlation effects were included by adopting the configuration interaction method. The Breit–Pauli approximation for quasirelativistic Hartree–Fock radial orbitals was employed to take into account relativistic effects. The energy level spectra, radiative lifetimes, Lande factors g were calculated for the 4p 6 4d, 4p 6 4f and 4p 5 4d 2 configurations of W 37+ ion. The atomic data, namely, the transition wavelengths, spontaneous emission rates and oscillator strengths for the electric dipole, electric quadrupole and magnetic dipole transitions among and within the levels of these configurations are tabulated.

Consideration of Relativistic Dynamics in High-Energy Electron Coolers

CERN Document Server

Bruhwiler, David L

2005-01-01

A proposed electron cooler for RHIC would use ~55 MeV electrons to cool fully-ionized 100 GeV/nucleon gold ions.* At two locations in the collider ring, the electrons and ions will co-propagate for ~13 m, with velocities close to c and gamma>100. To lowest-order, one can Lorentz transform all physical quantities into the beam frame and calculate the dynamical friction forces assuming a nonrelativisitc, electrostatic plasma. However, we show that nonlinear space charge forces of the bunched electron beam on the ions must be calculated relativistically, because an electrostatic beam-frame calculation is not valid for such short interaction times. The validity of nonrelativistic friction force calculations must also be considered. Further, the transverse thermal velocities of the high-charge (~20 nC) electron bunch are large enough that some electrons have marginally relativistic velocities, even in the beam frame. Hence, we consider relativistic binary collisions – treating the model problem of ...

Relativistic DFT calculations of hyperfine coupling constants in the 5d hexafluorido complexes

DEFF Research Database (Denmark)

Haase, Pi Ariane Bresling; Repisky, Michal; Komorovsky, Stanislav

2018-01-01

We have investigated the performance of the most popular relativistic density functional theory methods, zeroth order regular approximation (ZORA) and 4-component Dirac-Kohn-Sham (DKS), in the calculation of the recently measured hyperfine coupling constants of ReIV and IrIV in their hexafluorido...

Nonlinear interaction of a parallel-flow relativistic electron beam with a plasma

International Nuclear Information System (INIS)

Jungwirth, K.; Koerbel, S.; Simon, P.; Vrba, P.

1975-01-01

Nonlinear evolution of single-mode high-frequency instabilities (ω approximately ksub(parallel)vsub(b)) excited by a parallel-flow high-current relativistic electron beam in a magnetized plasma is investigated. Fairly general dimensionless equations are derived. They describe both the temporal and the spatial evolution of amplitude and phase of the fundamental wave. Numerically, the special case of excitation of the linearly most unstable mode is solved in detail assuming that the wave energy dissipation is negligible. Then the strength of interaction and the relativistic properties of the beam are fully respected by a single parameter lambda. The value of lambda ensuring the optimum efficiency of the wave excitation as well as the efficiency of the self-acceleration of some beam electrons at higher values of lambda>1 are determined in the case of a fully compensated relativistic beam. Finally, the effect of the return current dissipation is also included (phenomenologically) into the theoretical model, its role for the beam-plasma interaction being checked numerically. (J.U.)

Electric dipole moment of diatomic molecules by configuration interaction. V - Two states of /2/Sigma/+/ symmetry in CN.

Science.gov (United States)

Green, S.

1972-01-01

Previous accurate dipole moment calculation techniques are modified to be applicable to higher excited states of symmetry. The self-consistent fields and configuration interactions are calculated for the X(2)Sigma(+) and B(2)Sigma(+) states of CN. Spin hyperfine constants and spin density at the nucleus are considered in the context of one-electron operator properties. The values of the self-consistent field and configuration interaction for the spin density are compared with experimental values for several diatomic molecules.

Relativistic approach to the near-threshold phenomena in the nucleon-antinucleon interactions

International Nuclear Information System (INIS)

Shapiro, I.S.; Smirnov, A.V.

1997-01-01

It is shown that the strongest (∝r -3 ) singularities at small interparticle distances, arising from the spin-tensor forces in the standard nonrelativistic one-boson-exchange (OBE) potentials, disappear in the relativistic treatment of the NN- and NN-interactions. The partial wave analysis is performed in the framework of a relativistic OBE quasipotential model, and the results are compared with those obtained in the nonrelativistic approximation. (orig.)

Relativistic corrections to one-particle neutron levels in the harmonic oscillator well

International Nuclear Information System (INIS)

Yanavichyus, A.I.

1983-01-01

Relativistic corrections to mass and potential energy for one-particle levels in the harmonic oscillator well are calculated in the first approximation of the perturbation theory. These corrections are, mainly negliqible, but they sharply increase with growth of the head and orbital quantum numbers. For the state 1s the relativistic correction is of the order of 0.01 MeV, and for 3p it is equal to 0.4 MeV. Thus, the relativistic correction for certain states approaches the energy of spin-orbital interactions and it should be taken into account in calculating the energy of one-particle levels

Nuclear deformation in the configuration-interaction shell model

Science.gov (United States)

Alhassid, Y.; Bertsch, G. F.; Gilbreth, C. N.; Mustonen, M. T.

2018-02-01

We review a method that we recently introduced to calculate the finite-temperature distribution of the axial quadrupole operator in the laboratory frame using the auxiliary-field Monte Carlo technique in the framework of the configuration-interaction shell model. We also discuss recent work to determine the probability distribution of the quadrupole shape tensor as a function of intrinsic deformation β,γ by expanding its logarithm in quadrupole invariants. We demonstrate our method for an isotope chain of samarium nuclei whose ground states describe a crossover from spherical to deformed shapes.

Ultra-relativistic ion acceleration in the laser-plasma interactions

Energy Technology Data Exchange (ETDEWEB)

Huang Yongsheng; Wang Naiyan; Tang Xiuzhang; Shi Yijin [China Institute of Atomic Energy, Beijing 102413 (China); Xueqing Yan [Institute of Heavy Ion Physics, Peking University, Beijing 100871 (China)

2012-09-15

An analytical relativistic model is proposed to describe the relativistic ion acceleration in the interaction of ultra-intense laser pulses with thin-foil plasmas. It is found that there is a critical value of the ion momentum to make sure that the ions are trapped by the light sail and accelerated in the radiation pressure acceleration (RPA) region. If the initial ion momentum is smaller than the critical value, that is in the classical case of RPA, the potential has a deep well and traps the ions to be accelerated, as the same described before by simulation results [Eliasson et al., New J. Phys. 11, 073006 (2009)]. There is a new ion acceleration region different from RPA, called ultra-relativistic acceleration, if the ion momentum exceeds the critical value. In this case, ions will experience a potential downhill. The dependence of the ion momentum and the self-similar variable at the ion front on the acceleration time has been obtained. In the ultra-relativistic limit, the ion momentum at the ion front is proportional to t{sup 4/5}, where t is the acceleration time. In our analytical hydrodynamical model, it is naturally predicted that the ion distribution from RPA is not monoenergetic, although the phase-stable acceleration mechanism is effective. The critical conditions of the laser and plasma parameters which identify the two acceleration modes have been achieved.

Ultra-relativistic ion acceleration in the laser-plasma interactions

International Nuclear Information System (INIS)

Huang Yongsheng; Wang Naiyan; Tang Xiuzhang; Shi Yijin; Xueqing Yan

2012-01-01

An analytical relativistic model is proposed to describe the relativistic ion acceleration in the interaction of ultra-intense laser pulses with thin-foil plasmas. It is found that there is a critical value of the ion momentum to make sure that the ions are trapped by the light sail and accelerated in the radiation pressure acceleration (RPA) region. If the initial ion momentum is smaller than the critical value, that is in the classical case of RPA, the potential has a deep well and traps the ions to be accelerated, as the same described before by simulation results [Eliasson et al., New J. Phys. 11, 073006 (2009)]. There is a new ion acceleration region different from RPA, called ultra-relativistic acceleration, if the ion momentum exceeds the critical value. In this case, ions will experience a potential downhill. The dependence of the ion momentum and the self-similar variable at the ion front on the acceleration time has been obtained. In the ultra-relativistic limit, the ion momentum at the ion front is proportional to t 4/5 , where t is the acceleration time. In our analytical hydrodynamical model, it is naturally predicted that the ion distribution from RPA is not monoenergetic, although the phase-stable acceleration mechanism is effective. The critical conditions of the laser and plasma parameters which identify the two acceleration modes have been achieved.

Optical spectroscopy and system–bath interactions in molecular aggregates with full configuration interaction Frenkel exciton model

Energy Technology Data Exchange (ETDEWEB)

Seibt, Joachim; Sláma, Vladislav; Mančal, Tomáš, E-mail: mancal@karlov.mff.cuni.cz

2016-12-20

Highlights: • Standard Frenkel exciton model is extended to include inter-band coupling. • It is formally linked with configuration interaction method of quantum chemistry. • Spectral shifts due to inter-band coupling are found in molecular aggregates. • Effects of peak amplitude redistribution in two-dimensional spectra are found. - Abstract: Standard application of the Frenkel exciton model neglects resonance coupling between collective molecular aggregate states with different number of excitations. These inter-band coupling terms are, however, of the same magnitude as the intra-band coupling between singly excited states. We systematically derive the Frenkel exciton model from quantum chemical considerations, and identify it as a variant of the configuration interaction method. We discuss all non-negligible couplings between collective aggregate states, and provide compact formulae for their calculation. We calculate absorption spectra of molecular aggregate of carotenoids and identify significant band shifts as a result of inter-band coupling. The presence of inter-band coupling terms requires renormalization of the system–bath coupling with respect to standard formulation, but renormalization effects are found to be weak. We present detailed discussion of molecular dimer and calculate its time-resolved two-dimensional Fourier transformed spectra to find weak but noticeable effects of peak amplitude redistribution due to inter-band coupling.

Relativistic klystrons

International Nuclear Information System (INIS)

Allen, M.A.; Azuma, O.; Callin, R.S.

1989-03-01

Experimental work is underway by a SLAC-LLNL-LBL collaboration to investigate the feasibility of using relativistic klystrons as a power source for future high gradient accelerators. Two different relativistic klystron configurations have been built and tested to date: a high grain multicavity klystron at 11.4 GHz and a low gain two cavity subharmonic buncher driven at 5.7 GHz. In both configurations power is extracted at 11.4 GHz. In order to understand the basic physics issues involved in extracting RF from a high power beam, we have used both a single resonant cavity and a multi-cell traveling wave structure for energy extraction. We have learned how to overcome our previously reported problem of high power RF pulse shortening, and have achieved peak RF power levels of 170 MW with the RF pulse of the same duration as the beam current pulse. 6 refs., 3 figs., 3 tabs

Frame dependence of world lines for directly interacting classical relativistic particles

International Nuclear Information System (INIS)

Molotkov, V.V.; Todorov, I.T.

1979-06-01

The motion of world lines is studied in the constraint Hamiltonian formulation of relativistic point particle dynamics. The particle world lines are shown to depend, in general (in the presence of interaction) on the choice of the equal time hyperplane (the only exception being the elastic scattering of rigid balls). However, the relative motion of a 2-particle system and the (classical) S-matrix are independent of this choice. This inferred that particle trajectories should not be regarded as frame independent observables in the classical theory of relativistic particles. (author)

General relativistic dynamics of an extreme mass-ratio binary interacting with an external body

Science.gov (United States)

Yang, Huan; Casals, Marc

2017-10-01

We study the dynamics of a hierarchical three-body system in the general relativistic regime: an extreme mass-ratio inner binary under the tidal influence of an external body. The inner binary consists of a central Schwarzschild black hole and a test body moving around it. We discuss three types of tidal effects on the orbit of the test body. First, the angular momentum of the inner binary precesses around the angular momentum of the outer binary. Second, the tidal field drives a "transient resonance" when the radial and azimuthal frequencies are commensurable. In contrast with resonances driven by the gravitational self-force, this tidal-driven resonance may boost the orbital angular momentum and eccentricity (a relativistic version of the Kozai-Lidov effect). Finally, for an orbit-dynamical effect during the nonresonant phase, we calculate the correction to the innermost stable circular (mean) orbit due to the tidal interaction. Hierarchical three-body systems are potential sources for future space-based gravitational wave missions, and the tidal effects that we find could contribute significantly to their waveform.

Interactions of relativistic heavy ions in thick heavy element targets and some unresolved problems

International Nuclear Information System (INIS)

Brandt, R.; Ditlov, V.A.; Pozharova, E.A.; Smirnitskij, V.A.

2005-01-01

Interactions of relativistic heavy ions with total energies above 30 GeV in thick Cu and Pb targets (≥2 cm) have been studied with various techniques. Radiochemical irradiation experiments using thick Cu targets, both in a compact form or as diluted '2π-Cu targets' have been carried out with several relativistic heavy ions, such as 44 GeV 12 C (JINR, Dubna) and 72 GeV 40 Ar (LBL, Berkeley, USA). Neutron measuring experiments using thick targets irradiated with various relativistic heavy ions up to 44 GeV 12 C have been performed at JINR. In addition, the number of 'black prongs' in nuclear interactions (due to protons with energies less than 30 MeV and emitted from the target-like interaction partner at rest) produced with 72 GeV 22 Ne ions in nuclear emulsion plates has been measured in the first nuclear interaction of the primary 22 Ne ion and in the following second nuclear interaction of the secondary heavy (Z>1) ion. Some essential results have been obtained. 1) Spallation products produced by relativistic secondary fragments in interactions ([44 GeV 12 C or 72 GeV 40 Ar]+Cu) within thick copper yield less products close to the target and much more products far away from the target as compared to primary beam interactions. This applies also to secondary particles emitted into large angles (Θ>10deg). 2) The neutron production of 44 GeV 12 C within thick Cu and Pb targets is beyond the estimated yield as based on experiments with 12 GeV 12 C. These rather independent experimental results cannot be understood with well-accepted nuclear reaction models. They appear to present unresolved problems

Electrodisintegration of relativistic nuclei by a periodic crystal field in channeling

International Nuclear Information System (INIS)

Pivovarov, Yu.L.; Vorob'ev, S.A.

1981-01-01

Processes on channeled relativistic nuclei with transition into a continuous spectrum (electrodisintegration of nuclei with emission of neutron, proton, photon and etc.) are considered. A case of plane channeling is considered. The equivalent photon method is used for calculating the disintegration cross section. The beryllium disintegration cross section in the system of tungsten crystal (100) planes is calculated. At the γ=10 2 Lorentz factor the cross section value is 5.27 mb. The process considered is of interest from the viewpoint of production of monoenergy neutrons of high energies and γ quanta of excited nuclei. The channeling effect gives the possibility to study electromagnetic interactions of relativistic nuclei under suppre--ssion conditions of the nuclear interaction channel [ru

Spin-orbit interaction effects in zincblende semiconductors: Ab initio pseudopotential calculations

International Nuclear Information System (INIS)

Li, Ming-Fu; Surh, M.P.; Louie, S.G.

1988-06-01

Ab initio band structure calculations have been performed for the spin-orbit interaction effects at the top of the valence bands for GaAs and InSb. Relativistic, norm-conserving pseudopotentials are used with no correction made for the gaps from the local density approximation. The spin-orbit splitting at Γ and linear terms in the /rvec char/k dependence of the splitting are found to be in excellent agreement with existing experiments and previous theoretical results. The effective mass and the cubic splitting terms are also examined. 6 refs., 1 fig., 2 tabs

Gauge invariance and relativistic effects in X-ray absorption and scattering by solids

International Nuclear Information System (INIS)

Bouldi, N.; Brouder, C.

2017-01-01

There is an incompatibility between gauge invariance and the semi-classical time-dependent perturbation theory commonly used to calculate light absorption and scattering cross-sections. There is an additional incompatibility between perturbation theory and the description of the electron dynamics by a semi-relativistic Hamiltonian. In this paper, the gauge-dependence problem of exact perturbation theory is described, the proposed solutions are reviewed and it is concluded that none of them seems fully satisfactory. The problem is finally solved by using the fully relativistic absorption and scattering cross-sections given by quantum electrodynamics. Then, a new general Foldy-Wouthuysen transformation is presented. It is applied to the many-body case to obtain correct semi-relativistic transition operators. This transformation considerably simplifies the calculation of relativistic corrections. In the process, a new light-matter interaction term emerges, called the spin-position interaction, that contributes significantly to the magnetic X-ray circular dichroism of transition metals. We compare our result with the ones obtained by using several semi-relativistic time-dependent Hamiltonians. In the case of absorption, the final formula agrees with the result obtained from one of them. However, the correct scattering cross-section is not given by any of the semi-relativistic Hamiltonians. (authors)

Gamow-Teller response in the configuration space of a density-functional-theory-rooted no-core configuration-interaction model

Science.gov (United States)

Konieczka, M.; Kortelainen, M.; Satuła, W.

2018-03-01

Background: The atomic nucleus is a unique laboratory in which to study fundamental aspects of the electroweak interaction. This includes a question concerning in medium renormalization of the axial-vector current, which still lacks satisfactory explanation. Study of spin-isospin or Gamow-Teller (GT) response may provide valuable information on both the quenching of the axial-vector coupling constant as well as on nuclear structure and nuclear astrophysics. Purpose: We have performed a seminal calculation of the GT response by using the no-core configuration-interaction approach rooted in multireference density functional theory (DFT-NCCI). The model treats properly isospin and rotational symmetries and can be applied to calculate both the nuclear spectra and transition rates in atomic nuclei, irrespectively of their mass and particle-number parity. Methods: The DFT-NCCI calculation proceeds as follows: First, one builds a configuration space by computing relevant, for a given physical problem, (multi)particle-(multi)hole Slater determinants. Next, one applies the isospin and angular-momentum projections and performs the isospin and K mixing in order to construct a model space composed of linearly dependent states of good angular momentum. Eventually, one mixes the projected states by solving the Hill-Wheeler-Griffin equation. Results: The method is applied to compute the GT strength distribution in selected N ≈Z nuclei including the p -shell 8Li and 8Be nuclei and the s d -shell well-deformed nucleus 24Mg. In order to demonstrate a flexibility of the approach we present also a calculation of the superallowed GT β decay in doubly-magic spherical 100Sn and the low-spin spectrum in 100In. Conclusions: It is demonstrated that the DFT-NCCI model is capable of capturing the GT response satisfactorily well by using a relatively small configuration space, exhausting simultaneously the GT sum rule. The model, due to its flexibility and broad range of applicability, may

Relativistic rapprochement of weak and strong interactions

International Nuclear Information System (INIS)

Strel'tsov, V.N.

1995-01-01

On the basis of the relativistic Yukawa potentials for the nuclear (quark) field and the field of intermediate vector W-, Z-bosons, it is shown that the interactions described by them increase differently with growing velocity (the weak one increases more rapidly). According to the estimates, they are compared (at distances of the 'action radius' of nuclear forces) at an energy of about 10 12 GeV (10 6 GeV for the pion field) what is smaller than the corresponding value in the model of 'grand unification'. 3 refs., 2 tabs

Relativistic quantum information in detectors–field interactions

International Nuclear Information System (INIS)

Hu, B L; Lin, Shih-Yuin; Louko, Jorma

2012-01-01

We review Unruh–DeWitt detectors and other models of detector–field interaction in a relativistic quantum field theory setting as a tool for extracting detector–detector, field–field and detector–field correlation functions of interest in quantum information science, from entanglement dynamics to quantum teleportation. In particular, we highlight the contrast between the results obtained from linear perturbation theory which can be justified provided switching effects are properly accounted for, and the nonperturbative effects from available analytic expressions which incorporate the backreaction effects of the quantum field on the detector behavior. (paper)

Correlation and relativistic effects for the 4f-nl and 5p-nl multipole transitions in Er-like tungsten

International Nuclear Information System (INIS)

Safronova, U. I.; Safronova, A. S.

2011-01-01

Wavelengths, transition rates, and line strengths are calculated for the multipole (E1, M1, E2, M2, E3, and M3) transitions between the excited [Cd]4f 13 5p 6 nl, [Cd]4f 14 5p 5 nl configurations and the ground [Cd]4f 14 5p 6 state in Er-like W 6+ ion ([Cd]=[Kr]4d 10 5s 2 ). In particular, the relativistic many-body perturbation theory (RMBPT), including the Breit interaction, is used to evaluate energies and transition rates for multipole transitions in this hole-particle system. This method is based on the relativistic many-body perturbation theory that agrees with multiconfiguration Dirac-Fock (MCDF) calculations in lowest order, and includes all second-order correlation corrections and corrections from negative-energy states. The calculations start from a [Cd]4f 14 5p 6 Dirac-Fock (DF) potential. First-order perturbation theory is used to obtain intermediate-coupling coefficients, and second-order RMBPT is used to determine the multipole matrix elements needed for calculations of other atomic properties such as line strengths and transition rates. In addition, core multipole polarizability is evaluated in random-phase and DF approximations. The comparison with available data is demonstrated.

Critical comparison between equation of motion-Green's function methods and configuration interaction methods: analysis of methods and applications

International Nuclear Information System (INIS)

Freed, K.F.; Herman, M.F.; Yeager, D.L.

1980-01-01

A description is provided of the common conceptual origins of many-body equations of motion and Green's function methods in Liouville operator formulations of the quantum mechanics of atomic and molecular electronic structure. Numerical evidence is provided to show the inadequacies of the traditional strictly perturbative approaches to these methods. Nonperturbative methods are introduced by analogy with techniques developed for handling large configuration interaction calculations and by evaluating individual matrix elements to higher accuracy. The important role of higher excitations is exhibited by the numerical calculations, and explicit comparisons are made between converged equations of motion and configuration interaction calculations for systems where a fundamental theorem requires the equality of the energy differences produced by these different approaches. (Auth.)

SCRIC: a code dedicated to the detailed emission and absorption of heterogeneous NLTE plasmas; application to xenon EUV sources; SCRIC: un code pour calculer l'absorption et l'emission detaillees de plasmas hors equilibre, inhomogenes et etendus; application aux sources EUV a base de xenon

Energy Technology Data Exchange (ETDEWEB)

Gaufridy de Dortan, F. de

2006-07-01

Nearly all spectral opacity codes for LTE and NLTE plasmas rely on configurations approximate modelling or even supra-configurations modelling for mid Z plasmas. But in some cases, configurations interaction (either relativistic and non relativistic) induces dramatic changes in spectral shapes. We propose here a new detailed emissivity code with configuration mixing to allow for a realistic description of complex mid Z plasmas. A collisional radiative calculation. based on HULLAC precise energies and cross sections. determines the populations. Detailed emissivities and opacities are then calculated and radiative transfer equation is resolved for wide inhomogeneous plasmas. This code is able to cope rapidly with very large amount of atomic data. It is therefore possible to use complex hydrodynamic files even on personal computers in a very limited time. We used this code for comparison with Xenon EUV sources within the framework of nano-lithography developments. It appears that configurations mixing strongly shifts satellite lines and must be included in the description of these sources to enhance their efficiency. (author)

Theoretical level energies and transition data for 4p64d4, 4p64d34f and 4p54d5 configurations of W34+ ion

Science.gov (United States)

Karpuškienė, R.; Bogdanovich, P.; Kisielius, R.

2017-05-01

The ab initio quasirelativistic approach developed specifically for the calculation of spectral parameters of highly charged ions was used to derive transition data for the tungsten ion W34+. The configuration interaction method was applied to include electron correlation effects. The relativistic effects were taken into account in the Breit-Pauli approximation. The level energies, radiative lifetimes τ, Landé g-factors are determined for the ground configuration 4p64d4 and two excited configurations 4p64d34f and 4p54d5. The radiative transition wavelengths λ and emission transition probabilities A for the electric dipole, electric quadrupole, electric octupole, magnetic dipole, and magnetic quadrupole transitions among the levels of these configurations are produced.

MODELES ET CALCUL DES SYSTEMES DE SUSPENSION MAGNETIQUE PASSIVE -DEVELOPPEMENTS ET CALCULS ANALYTIQUES EN 2D ET 3D DES INTERACTIONS ENTRE AIMANTS PERMANENTS-

OpenAIRE

Allag , Hicham

2010-01-01

The passive magnetic suspensions operate using attractive or repulsive forces exerted between permanent magnets. After giving an overview of different possible configurations of magnetic suspensions, the calculation of interactions between permanent magnets was developed. The calculations are realised for parallelepipeds magnets, where the magnetization is represented by distributions of charges or poles (Coulombian approach). All interactions (energy, forces, torques, etc ....) was calculate...

Proton relativistic model

International Nuclear Information System (INIS)

Araujo, Wilson Roberto Barbosa de

1995-01-01

In this dissertation, we present a model for the nucleon, which is composed by three relativistic quarks interacting through a contract force. The nucleon wave-function was obtained from the Faddeev equation in the null-plane. The covariance of the model under kinematical null-plane boots is discussed. The electric proton form-factor, calculated from the Faddeev wave-function, was in agreement with the data for low-momentum transfers and described qualitatively the asymptotic region for momentum transfers around 2 GeV. (author)

Beta decay and muon capture rates in a self-consistent relativistic framework

Energy Technology Data Exchange (ETDEWEB)

Marketin, Tomislav; Paar, Nils; Niksic, Tamara; Vretenar, Dario [Physics Department, Faculty of Science, University of Zagreb (Croatia); Ring, Peter [Physik-Department, Technische Universitaet Muenchen, D-85748 Muenchen (Germany)

2009-07-01

A fully consistent calculation of muon capture and beta decay rates is presented, based on a microscopic theoretical framework describing the semileptonic weak interaction processes. Nuclear ground state is determined using the Relativistic Hartree-Bogolyubov (RHB) model with density dependent meson-nucleon coupling constants, and transition rates are calculated via proton-neutron relativistic quasiparticle RPA using the same interaction as in the RHB equations. Muon capture rates are calculated for a wide range of nuclei along the valley of stability, from {sup 12}C to {sup 244}Pu, with accuracy of approximately 30%, using the interaction DD-ME2. Previous studies of beta decay rates have only taken into account Gamow-Teller transitions. We extend this approach by including forbidden transitions and systematically study their contribution to decay rates of exotic nuclei along the r-process path, which are important for constraining the conditions in which nucleosynthesis takes place.

Non-relativistic and relativistic quantum kinetic equations in nuclear physics

International Nuclear Information System (INIS)

Botermans, W.M.M.

1989-01-01

In this thesis an attempt is made to draw up a quantummechanical tranport equation for the explicit calculation oof collision processes between two (heavy) ions, by making proper approaches of the exact equations (non-rel.: N-particles Schroedinger equation; rel.: Euler-Lagrange field equations.). An important starting point in the drag-up of the theory is the behaviour of nuclear matter in equilibrium which is determined by individual as well as collective effects. The central point in this theory is the effective interaction between two nucleons both surrounded by other nucleons. In the derivation of the tranport equations use is made of the green's function formalism as developed by Schwinger and Keldys. For the Green's function kinematic equations are drawn up and are solved by choosing a proper factorization of three- and four-particle Green's functions in terms of one- and two-particle Green's functions. The necessary boundary condition is obtained by explicitly making use of Boltzmann's assumption that colliding particles are statistically uncorrelated. Finally a transport equation is obtained in which the mean field as well as the nucleon-nucleon collisions are given by the same (medium dependent) interaction. This interaction is the non-equilibrium extension of the interaction as given in the Brueckner theory of nuclear matter. Together, kinetic equation and interaction, form a self-consistent set of equations for the case of a non-relativistic as well as for the case of a relativistic starting point. (H.W.) 148 refs.; 6 figs.; 411 schemes

Relativistic effects in the Thomas--Fermi atom

International Nuclear Information System (INIS)

Waber, J.T.; Canfield, J.M.

1975-01-01

Two methods of applying relativistic corrections to the Thomas--Fermi atom are considered, and numerical calculations are discussed. Radial charge distributions calculated from a relativistic Thomas--Fermi equation agree in gross form with those from more complicated self-consistent calculations. Energy eigenvalues for mercury, as determined from the relativistic Thomas--Fermi solution, are compared with other calculated and experimental values

Relativistic treatment of mesonic contributions to quasielastic (e,e')

International Nuclear Information System (INIS)

Blunden, P.G.; Butler, M.N.

1988-03-01

Meson exchange currents play an important role in the description of observables in electron scattering. The authors use a relativistic model with pseudovector pion coupling to study the exchange current contributions, with emphasis on quasielastic kinematics. Starting with the Lagrangian for nucleons interacting with a scalar and vector mason along with pseudovector coupling to pions, they derive the one and two-body electromagnetic currents. They then calculate the longitudinal and transverse pieces of the quasielastic cross section for various nuclei and kinematics. The effects of meson exchange currents are found to be much more important in a relativistic model than in a non-relativistic one

Heuristic models of two-fermion relativistic systems with field-type interaction

International Nuclear Information System (INIS)

Duviryak, A

2002-01-01

We use the chain of simple heuristic expedients for obtaining perturbative and exactly solvable relativistic spectra for a family of two-fermionic bound systems with Coulomb-like interaction. In the case of electromagnetic interaction the spectrum coincides up to the second order in a coupling constant with that following from the quantum electrodynamics. Discrepancy occurs only for S-states which is the well-known difficulty in the bound-state problem. The confinement interaction is considered too

Restricted magnetically balanced basis applied for relativistic calculations of indirect nuclear spin-spin coupling tensors in the matrix Dirac-Kohn-Sham framework

International Nuclear Information System (INIS)

Repisky, Michal; Komorovsky, Stanislav; Malkina, Olga L.; Malkin, Vladimir G.

2009-01-01

The relativistic four-component density functional approach based on the use of restricted magnetically balanced basis (mDKS-RMB), applied recently for calculations of NMR shielding, was extended for calculations of NMR indirect nuclear spin-spin coupling constants. The unperturbed equations are solved with the use of a restricted kinetically balanced basis set for the small component while to solve the second-order coupled perturbed DKS equations a restricted magnetically balanced basis set for the small component was applied. Benchmark relativistic calculations have been carried out for the X-H and H-H spin-spin coupling constants in the XH 4 series (X = C, Si, Ge, Sn and Pb). The method provides an attractive alternative to existing approximate two-component methods with transformed Hamiltonians for relativistic calculations of spin-spin coupling constants of heavy-atom systems. In particular, no picture-change effects arise in our method for property calculations

Variational configuration interaction methods and comparison with perturbation theory

International Nuclear Information System (INIS)

Pople, J.A.; Seeger, R.; Krishnan, R.

1977-01-01

A configuration interaction (CI) procedure which includes all single and double substitutions from an unrestricted Hartree-Fock single determinant is described. This has the feature that Moller-Plesset perturbation results to second and third order are obtained in the first CI iterative cycle. The procedure also avoids the necessity of a full two-electron integral transformation. A simple expression for correcting the final CI energy for lack of size consistency is proposed. Finally, calculations on a series of small molecules are presented to compare these CI methods with perturbation theory

Electronic excitation of molecules in solution calculated using the symmetry-adapted cluster–configuration interaction method in the polarizable continuum model

International Nuclear Information System (INIS)

Fukuda, Ryoichi; Ehara, Masahiro

2015-01-01

The effects from solvent environment are specific to the electronic states; therefore, a computational scheme for solvent effects consistent with the electronic states is necessary to discuss electronic excitation of molecules in solution. The PCM (polarizable continuum model) SAC (symmetry-adapted cluster) and SAC-CI (configuration interaction) methods are developed for such purposes. The PCM SAC-CI adopts the state-specific (SS) solvation scheme where solvent effects are self-consistently considered for every ground and excited states. For efficient computations of many excited states, we develop a perturbative approximation for the PCM SAC-CI method, which is called corrected linear response (cLR) scheme. Our test calculations show that the cLR PCM SAC-CI is a very good approximation of the SS PCM SAC-CI method for polar and nonpolar solvents

Form factor of relativistic two-particle system and covariant hamiltonian formulation of quantum field theory

International Nuclear Information System (INIS)

Skachkov, N.; Solovtsov, I.

1979-01-01

Based on the hamiltonian formulation of quantum field theory proposed by Kadyshevsky the three-dimensional relativistic approach is developed for describing the form factors of composite systems. The main features of the diagram technique appearing in the covariant hamiltonian formulation of field theory are discussed. The three-dimensional relativistic equation for the vertex function is derived and its connection with that for the quasipotential wave function is found. The expressions are obtained for the form factor of the system through equal-time two-particle wave functions both in momentum and relativistic configurational representations. An explicit expression for the form factor is found for the case of two-particle interaction through the Coulomb potential

Relativistic calculations of screening parameters and atomic radii of neutral atoms

Science.gov (United States)

Guerra, M.; Amaro, P.; Santos, J. P.; Indelicato, P.

2017-09-01

Calculations of the effective nuclear charge for elements with 1 ≤ Z ≤ 118 have been performed in a Dirac-Fock approach including all relativistic effects as well as contributions from quantum electrodynamics. Maximum charge density for every subshell of every element in the periodic table was also computed in the same framework as well as atomic radii based on the total charge density. Results were compared with the extensively cited works of Clementi et al., obtained in the 1960s with Roothan's self-consistent-field method.

Decomposition of the configuration-interaction coefficients in the multiconfiguration time-dependent Hartree-Fock method

Energy Technology Data Exchange (ETDEWEB)

Lötstedt, Erik, E-mail: lotstedt@chem.s.u-tokyo.ac.jp; Kato, Tsuyoshi; Yamanouchi, Kaoru [Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)

2016-04-21

An approximate implementation of the multiconfiguration time-dependent Hartree-Fock method is proposed, in which the matrix of configuration-interaction coefficients is decomposed into a product of matrices of smaller dimension. The applicability of this method in which all the configurations are kept in the expansion of the wave function, while the configuration-interaction coefficients are approximately calculated, is discussed by showing the results on three model systems: a one-dimensional model of a beryllium atom, a one-dimensional model of a carbon atom, and a one-dimensional model of a chain of four hydrogen atoms. The time-dependent electronic dynamics induced by a few-cycle, long-wavelength laser pulse is found to be well described at a lower computational cost compared to the standard multiconfiguration time-dependent Hartree-Fock treatment. Drawbacks of the method are also discussed.

Derivation of a configuration space Hamiltonian for heavy atoms: three body potentials

International Nuclear Information System (INIS)

Mittleman, M.H.

1981-01-01

A brief history of the difficulties associated with the derivation of a configuration space Hamiltonian is presented. One of the problems encountered is the definition of the projection operators which must occur. A variational definition is obtained and, with simplifying assumptions, the optimum projection operators are those which project onto Hartree-Fock orbitals. This puts many previously performed numerical calculations on a firm footing. The form of the two body interactions is discussed in the context of the gauge freedom. The Coulomb gauge is the favored one but it is pointed out that it has never been proven to be the best one. Finally a form for the relativistic three election potential is given and the possibility of its observation is discussed

Specular Reflectivity and Hot-Electron Generation in High-Contrast Relativistic Laser-Plasma Interactions

Energy Technology Data Exchange (ETDEWEB)

Kemp, Gregory Elijah [The Ohio State Univ., Columbus, OH (United States)

2013-01-01

Ultra-intense laser (> 1018 W/cm2) interactions with matter are capable of producing relativistic electrons which have a variety of applications in state-of-the-art scientific and medical research conducted at universities and national laboratories across the world. Control of various aspects of these hot-electron distributions is highly desired to optimize a particular outcome. Hot-electron generation in low-contrast interactions, where significant amounts of under-dense pre-plasma are present, can be plagued by highly non-linear relativistic laser-plasma instabilities and quasi-static magnetic field generation, often resulting in less than desirable and predictable electron source characteristics. High-contrast interactions offer more controlled interactions but often at the cost of overall lower coupling and increased sensitivity to initial target conditions. An experiment studying the differences in hot-electron generation between high and low-contrast pulse interactions with solid density targets was performed on the Titan laser platform at the Jupiter Laser Facility at Lawrence Livermore National Laboratory in Livermore, CA. To date, these hot-electrons generated in the laboratory are not directly observable at the source of the interaction. Instead, indirect studies are performed using state-of-the-art simulations, constrained by the various experimental measurements. These measurements, more-often-than-not, rely on secondary processes generated by the transport of these electrons through the solid density materials which can susceptible to a variety instabilities and target material/geometry effects. Although often neglected in these types of studies, the specularly reflected light can provide invaluable insight as it is directly influenced by the interaction. In this thesis, I address the use of (personally obtained) experimental specular reflectivity measurements to indirectly study hot-electron generation in the context of high-contrast, relativistic

Renormalization of NN Interaction with Relativistic Chiral Two Pion Exchange

Energy Technology Data Exchange (ETDEWEB)

Higa, R; Valderrama, M Pavon; Arriola, E Ruiz

2007-06-14

The renormalization of the NN interaction with the Chiral Two Pion Exchange Potential computed using relativistic baryon chiral perturbation theory is considered. The short distance singularity reduces the number of counter-terms to about a half as those in the heavy-baryon expansion. Phase shifts and deuteron properties are evaluated and a general overall agreement is observed.

Relativistic corrections to fine structure of positronium

International Nuclear Information System (INIS)

Martynenko, A.P.; Faustov, R.N.

1997-01-01

On the basis of the quasipotential method, we have calculated the relativistic corrections in the positronium fine structure intervals 2 3 S 1 -2 3 P J . The contributions of order of mα 6 for the positronium S-levels were obtained from the one-photon, two-photon interactions and the second-order perturbation theory. We have obtained also the contribution of the two-photon annihilation diagrams to the interaction operator of the P-wave positronium. The corrections of order of α 5 R ∞ and α 5 1nαR ∞ to the P-wave energy levels of positronium were calculated

Detailed spectra of high power broadband microwave radiation from interactions of relativistic electron beams with weakly magnetized plasmas

International Nuclear Information System (INIS)

Kato, K.G.; Benford, G.; Tzach, D.

1983-01-01

Prodigious quantities of microwave energy are observed uniformly across a wide frequency band when a relativistic electron beam (REB) penetrates a plasma. Measurement calculations are illustrated. A model of Compton-like boosting of ambient plasma waves by beam electrons, with collateral emission of high frequency photons, qualitatively explain the spectra. A transition in spectral behavior is observed from the weak to strong turbulence theories advocated for Type III solar burst radiation, and further into the regime the authors characterize as super-strong REB-plasma interactions

Relativistic corrections to the fine structure of positronium

International Nuclear Information System (INIS)

Faustov, R. N.; Martynenko, A. P.

1997-01-01

The quasipotential method is used to calculate relativistic corrections in the positronium-fine-structure intervals 2 3 S 1 -2 3 P J . From analysis of one- and two-photon interactions, corrections of order mα 6 are found for positronium S states in the second order of perturbation theory. The contribution of the two-photon annihilation diagrams to the interaction operator for P-wave positronium is determined, and corrections of orders α 5 R ∞ and α 5 ln αR ∞ to the P-wave levels of positronium are calculated

Relativistic actions for bound-states and applications in the meson spectroscopy; Acoes relativisticas para estados ligados e aplicacoes na espectroscopia de mesons

Energy Technology Data Exchange (ETDEWEB)

Silva Carvalho, Hendly da

1991-08-01

We study relativistic equations for bound states of two-body systems using Dirac`s constraint formalism and supersymmetry. The two-body system can be of spinless particles, one of them spinning and the other one spinless, or both of them spinning. The interaction is described by scalar, timelike four-vector and spacelike four-vector potentials under Lorentz transformations. As an application we use the relativistic wave equation for two scalar particles and calculate the mass spectra of the mesons treating them as spinless quark-antiquark bound states. The interaction potential in this case is a convenient adaptation of the potential employed in non-relativistic calculations. Finally, we compare our results with more recent experimental data and with theoretical results obtained with the same potential used by us but with a non-relativistic wave equation. We also compare our results with results obtained with the relativistic wave equation but with a different interaction potential. (author). 38 refs, 9 figs, 8 tabs.

Relativity and Electron Correlation in Chemistry

NARCIS (Netherlands)

Visscher, Lucas

1993-01-01

In this thesis we describe a method for relativistic quantum mechanical calculations on molecules. We obtain relativistic zero order wave functions by the use of the Dirac-Fock method and improve these by relativistic Configuration Interaction. This opens the way for an accurate ab initio treatment

β-decay rates of r-process nuclei in the relativistic quasiparticle random phase approximation

International Nuclear Information System (INIS)

Niksic, T.; Marketin, T.; Vretenar, D.; Paar, N.; Ring, P.

2005-01-01

The fully consistent relativistic proton-neutron quasiparticle random phase approximation (PN-RQRPA) is employed in the calculation of β-decay half-lives of neutron-rich nuclei in the N≅50 and N≅82 regions. A new density-dependent effective interaction, with an enhanced value of the nucleon effective mass, is used in relativistic Hartree-Bogoliubov calculation of nuclear ground states and in the particle-hole channel of the PN-RQRPA. The finite range Gogny D1S interaction is employed in the T=1 pairing channel, and the model also includes a proton-neutron particle-particle interaction. The theoretical half-lives reproduce the experimental data for the Fe, Zn, Cd, and Te isotopic chains but overestimate the lifetimes of Ni isotopes and predict a stable 132 Sn

Possibility of ΛΛ pairing and its dependence on background density in a relativistic Hartree-Bogoliubov model

International Nuclear Information System (INIS)

Tanigawa, Tomonori; Matsuzaki, Masayuki; Chiba, Satoshi

2003-01-01

We calculate a ΛΛ pairing gap in binary mixed matter of nucleons and Λ hyperons within the relativistic Hartree-Bogoliubov model. Λ hyperons to be paired up are immersed in background nucleons in a normal state. The gap is calculated with a one-boson-exchange interaction obtained from a relativistic Lagrangian. It is found that at background density ρ N =2.5ρ 0 the ΛΛ pairing gap is very small, and that a denser background makes it rapidly suppressed. This result suggests a mechanism, specific to mixed matter dealt with relativistic models, of its dependence on the nucleon density. An effect of weaker ΛΛ attraction on the gap is also examined in connection with the revised information of the ΛΛ interaction

A combined photoelectron spectroscopy and relativistic ab initio studies of the electronic structures of UFO and UFO-

Science.gov (United States)

Roy, Soumendra K.; Jian, Tian; Lopez, Gary V.; Li, Wei-Li; Su, Jing; Bross, David H.; Peterson, Kirk A.; Wang, Lai-Sheng; Li, Jun

2016-02-01

The observation of the gaseous UFO- anion is reported, which is investigated using photoelectron spectroscopy and relativisitic ab initio calculations. Two strong photoelectron bands are observed at low binding energies due to electron detachment from the U-7sσ orbital. Numerous weak detachment bands are also observed due to the strongly correlated U-5f electrons. The electron affinity of UFO is measured to be 1.27(3) eV. High-level relativistic quantum chemical calculations have been carried out on the ground state and many low-lying excited states of UFO to help interpret the photoelectron spectra and understand the electronic structure of UFO. The ground state of UFO- is linear with an O-U-F structure and a 3H4 spectral term derived from a U 7sσ25fφ15fδ1 electron configuration, whereas the ground state of neutral UFO has a 4H7/2 spectral term with a U 7sσ15fφ15fδ1 electron configuration. Strong electron correlation effects are found in both the anionic and neutral electronic configurations. In the UFO neutral, a high density of electronic states with strong configuration mixing is observed in most of the scalar relativistic and spin-orbit coupled states. The strong electron correlation, state mixing, and spin-orbit coupling of the electronic states make the excited states of UFO very challenging for accurate quantum chemical calculations.

A combined photoelectron spectroscopy and relativistic ab initio studies of the electronic structures of UFO and UFO(-).

Science.gov (United States)

Roy, Soumendra K; Jian, Tian; Lopez, Gary V; Li, Wei-Li; Su, Jing; Bross, David H; Peterson, Kirk A; Wang, Lai-Sheng; Li, Jun

2016-02-28

The observation of the gaseous UFO(-) anion is reported, which is investigated using photoelectron spectroscopy and relativisitic ab initio calculations. Two strong photoelectron bands are observed at low binding energies due to electron detachment from the U-7sσ orbital. Numerous weak detachment bands are also observed due to the strongly correlated U-5f electrons. The electron affinity of UFO is measured to be 1.27(3) eV. High-level relativistic quantum chemical calculations have been carried out on the ground state and many low-lying excited states of UFO to help interpret the photoelectron spectra and understand the electronic structure of UFO. The ground state of UFO(-) is linear with an O-U-F structure and a (3)H4 spectral term derived from a U 7sσ(2)5fφ(1)5fδ(1) electron configuration, whereas the ground state of neutral UFO has a (4)H(7/2) spectral term with a U 7sσ(1)5fφ(1)5fδ(1) electron configuration. Strong electron correlation effects are found in both the anionic and neutral electronic configurations. In the UFO neutral, a high density of electronic states with strong configuration mixing is observed in most of the scalar relativistic and spin-orbit coupled states. The strong electron correlation, state mixing, and spin-orbit coupling of the electronic states make the excited states of UFO very challenging for accurate quantum chemical calculations.

Accurate calculation of high harmonics generated by relativistic Thomson scattering

International Nuclear Information System (INIS)

Popa, Alexandru

2008-01-01

The recent emergence of the field of ultraintense laser pulses, corresponding to beam intensities higher than 10 18 W cm -2 , brings about the problem of the high harmonic generation (HHG) by the relativistic Thomson scattering of the electromagnetic radiation by free electrons. Starting from the equations of the relativistic motion of the electron in the electromagnetic field, we give an exact solution of this problem. Taking into account the Lienard-Wiechert equations, we obtain a periodic scattered electromagnetic field. Without loss of generality, the solution is strongly simplified by observing that the electromagnetic field is always normal to the direction electron-detector. The Fourier series expansion of this field leads to accurate expressions of the high harmonics generated by the Thomson scattering. Our calculations lead to a discrete HHG spectrum, whose shape and angular distribution are in agreement with the experimental data from the literature. Since no approximations were made, our approach is also valid in the ultrarelativistic regime, corresponding to intensities higher than 10 23 W cm -2 , where it predicts a strong increase of the HHG intensities and of the order of harmonics. In this domain, the nonlinear Thomson scattering could be an efficient source of hard x-rays

Relativistic quasiparticle random phase approximation with a separable pairing force

International Nuclear Information System (INIS)

Tian Yuan; Ma Zhongyu; Ring Peter

2009-01-01

In our previous work, we introduced a separable pairing force for relativistic Hartree-Bogoliubov calculations. This force was adjusted to reproduce the pairing properties of the Gogny force in nuclear matter. By using the well known techniques of Talmi and Moshinsky it can be expanded in a series of separable terms and converges quickly after a few terms. It was found that the pairing properties can be depicted on almost the same footing as the original pairing interaction, not only in nuclear matter, but also in finite nuclei. In this study, we construct a relativistic quasiparticle random phase approximation (RQRPA) with this separable pairing interaction and calculate the excitation energies of the first excited 2 + states and reduced B(E2; 0 + →2 + ) transition rates for a chain of Sn isotopes in RQRPA. Compared with the results of the full Gogny force, we find that this simple separable pairing interaction can describe the pairing properties of the excited vibrational states as well as the original pairing interaction. (authors)

Nonlinear analysis of a relativistic beam-plasma cyclotron instability

Science.gov (United States)

Sprangle, P.; Vlahos, L.

1986-01-01

A self-consistent set of nonlinear and relativistic wave-particle equations are derived for a magnetized beam-plasma system interacting with electromagnetic cyclotron waves. In particular, the high-frequency cyclotron mode interacting with a streaming and gyrating electron beam within a background plasma is considered in some detail. This interaction mode may possibly find application as a high-power source of coherent short-wavelength radiation for laboratory devices. The background plasma, although passive, plays a central role in this mechanism by modifying the dielectric properties in which the magnetized electron beam propagates. For a particular choice of the transverse beam velocity (i.e., the speed of light divided by the relativistic mass factor), the interaction frequency equals the nonrelativistic electron cyclotron frequency times the relativistic mass factor. For this choice of transverse beam velocity the detrimental effects of a longitudinal beam velocity spread is virtually removed. Power conversion efficiencies in excess of 18 percent are both analytically calculated and obtained through numerical simulations of the wave-particle equations. The quality of the electron beam, degree of energy and pitch angle spread, and its effect on the beam-plasma cyclotron instability is studied.

Ab initio MCHF structural calculations of Mg-like cerium

Science.gov (United States)

Wajid, Abdul; Jabeen, S.; Husain, Abid

2018-05-01

Energy levels and emission line wavelengths of high-Z materials are useful for impurity diagnostics in the next generation fusion devices. For this here we have calculated E1, M2 transitions, oscillator strengths, and transition probabilities for transitions among the terms belonging to the 2p63s2, 2p63s3p, 2p63p2 and 2p63s3d for the Magnesium like cerium (Ce XLVII) using the GRASP2K package based on the fully relativistic multi-configuration Dirac-Fock method. The electron correlation effects, Breit interaction and quantum electrodynamics effects to the atomic state wave functions and the corresponding energies have been taken into account.

Point form relativistic quantum mechanics and relativistic SU(6)

Science.gov (United States)

Klink, W. H.

1993-01-01

The point form is used as a framework for formulating a relativistic quantum mechanics, with the mass operator carrying the interactions of underlying constituents. A symplectic Lie algebra of mass operators is introduced from which a relativistic harmonic oscillator mass operator is formed. Mass splittings within the degenerate harmonic oscillator levels arise from relativistically invariant spin-spin, spin-orbit, and tensor mass operators. Internal flavor (and color) symmetries are introduced which make it possible to formulate a relativistic SU(6) model of baryons (and mesons). Careful attention is paid to the permutation symmetry properties of the hadronic wave functions, which are written as polynomials in Bargmann spaces.

Relativistic particle dynamics: Lagrangian proof of the no-interaction theorem

International Nuclear Information System (INIS)

Marmo, G.; Mukunda, N.; Sudarshan, E.C.G.

1983-11-01

An economical proof is given, in the Lagrangian framework, of the No Interaction Theorem of relativistic particle mechanics. It is based on the assumption that there is a Lagrangian, which if singular is allowed to lead at most to primary first class constraints. The proof works with Lagrange rather than Poisson brackets, leading to considerable simplifications compared to other proofs

Heavy baryons in the relativistic quark model

International Nuclear Information System (INIS)

Ebert, D.; Faustov, R.N.; Galkin, V.O.; Martynenko, A.P.; Saleev, V.A.

1996-07-01

In the framework of the relativistic quasipotential quark model the mass spectrum of baryons with two heavy quarks is calculated. The quasipotentials for interactions of two quarks and of a quark with a scalar and axial vector diquark are evaluated. The bound state masses of baryons with J P =1/2 + , 3/2 + are computed. (orig.)

Bonding and magnetic response properties of several toroid structures. Insights of the role of Ni2S2 as a building block from relativistic density functional theory calculations.

Science.gov (United States)

Muñoz-Castro, Alvaro

2011-10-06

Relativistic density functional calculations were carried out on several nickel toroid mercaptides of the general formula [Ni(μ-SR)(2)](n), with the aim to characterize and analyze their stability and magnetic response properties, in order to gain more insights into their stabilization and size-dependent behavior. The Ni-ligand interaction has been studied by means projected density of states and energy decomposition analysis, which denotes its stabilizing character. The graphical representation of the response to an external magnetic field is applied for the very first time taking into account the spin-orbit term. This map allows one to clearly characterize the magnetic behavior inside and in the closeness of the toroid structure showing the prescence of paratropic ring currents inside the Ni(n) ring, and by contrast, diatropic currents confined in each Ni(2)S(2) motif denoting an aromatic behavior (in terms of magnetic criteria). The calculated data suggests that the Ni(2)S(2) moiety can be regarded as a stable constructing block, which can afford several toroid structures of different nuclearities in agreement with that reported in the experimental literature. In addition, the effects of the relativistic treatment over the magnetic response properties on these lighter compounds are denoted by comparing nonrelativistic, scalar relativistic, and scalar plus spin-orbit relativistic treatments, showing their acting, although nonpronunced, role.

Neutrino-nucleus reaction rates based on the relativistic quasiparticle random phase approximation

International Nuclear Information System (INIS)

Paar, N.; Vretenar, D.; Marketin, T.; Ring, P.

2008-01-01

Neutrino-nucleus cross sections are described in a novel theoretical framework where the weak interaction of leptons with hadrons is expressed in the standard current-current form, the nuclear ground state is described in the relativistic Hartree-Bogoliubov model, and the relevant transitions to excited states are calculated in the relativistic quasiparticle random phase approximation. The model is employed in studies of neutrino-nucleus reactions in several test cases

Separable pairing force for relativistic quasiparticle random-phase approximation

International Nuclear Information System (INIS)

Tian Yuan; Ma Zhongyu; Ring, Peter

2009-01-01

We have introduced a separable pairing force, which was adjusted to reproduce the pairing properties of the Gogny force in nuclear matter. This separable pairing force is able to describe in relativistic Hartree-Bogoliubov (RHB) calculations the pairing properties in the ground state of finite nuclei on almost the same footing as the original Gogny interaction. In this work we investigate excited states using the Relativistic Quasiparticle Random-Phase Approximation (RQRPA) with the same separable pairing force. For consistency the Goldstone modes and the convergence with various cutoff parameters in this version of RQRPA are studied. The first excited 2 + states for the chain of Sn isotopes with Z=50 and the chain of isotones with N=82 isotones are calculated in RQRPA together with the 3 - states of Sn isotopes. By comparing our results with experimental data and with the results of the original Gogny force we find that this simple separable pairing interaction is very successful in depicting the pairing properties of vibrational excitations.

Valence ionized states of iron pentacarbonyl and eta5-cyclopentadienyl cobalt dicarbonyl studied by symmetry-adapted cluster-configuration interaction calculation and collision-energy resolved Penning ionization electron spectroscopy.

Science.gov (United States)

Fukuda, Ryoichi; Ehara, Masahiro; Nakatsuji, Hiroshi; Kishimoto, Naoki; Ohno, Koichi

2010-02-28

Valence ionized states of iron pentacarbonyl Fe(CO)(5) and eta(5)-cyclopentadienyl cobalt dicarbonyl Co(eta(5)-C(5)H(5))(CO)(2) have been studied by ultraviolet photoelectron spectroscopy, two-dimensional Penning ionization electron spectroscopy (2D-PIES), and symmetry-adapted cluster-configuration interaction calculations. Theory provided reliable assignments for the complex ionization spectra of these molecules, which have metal-carbonyl bonds. Theoretical ionization energies agreed well with experimental observations and the calculated wave functions could explain the relative intensities of PIES spectra. The collision-energy dependence of partial ionization cross sections (CEDPICS) was obtained by 2D-PIES. To interpret these CEDPICS, the interaction potentials between the molecules and a Li atom were examined in several coordinates by calculations. The relation between the slope of the CEDPICS and the electronic structure of the ionized states, such as molecular symmetry and the spatial distribution of ionizing orbitals, was analyzed. In Fe(CO)(5), an attractive interaction was obtained for the equatorial CO, while the interaction for the axial CO direction was repulsive. For Co(eta(5)-C(5)H(5))(CO)(2), the interaction potential in the direction of both Co-C-O and Co-Cp ring was attractive. These anisotropic interactions and ionizing orbital distributions consistently explain the relative slopes of the CEDPICS.

Isoscalar compression modes in relativistic random phase approximation

International Nuclear Information System (INIS)

Ma, Zhong-yu; Van Giai, Nguyen.; Wandelt, A.; Vretenar, D.; Ring, P.

2001-01-01

Monopole and dipole compression modes in nuclei are analyzed in the framework of a fully consistent relativistic random phase approximation (RRPA), based on effective mean-field Lagrangians with nonlinear meson self-interaction terms. The large effect of Dirac sea states on isoscalar strength distribution functions is illustrated for the monopole mode. The main contribution of Fermi and Dirac sea pair states arises through the exchange of the scalar meson. The effect of vector meson exchange is much smaller. For the monopole mode, RRPA results are compared with constrained relativistic mean-field calculations. A comparison between experimental and calculated energies of isoscalar giant monopole resonances points to a value of 250-270 MeV for the nuclear matter incompressibility. A large discrepancy remains between theoretical predictions and experimental data for the dipole compression mode

Relativistic description of directly interacting pions and nucleons

International Nuclear Information System (INIS)

Heller, L.

1976-01-01

The expected magnitudes of the leading relativistic effects on an off-energy-shell T matrix element are estimated using the Bakamjian--Thomas formulation of relativistic potential theory. For pion-nucleon scattering at medium energy, the two largest corrections are expected to result from the use of relativistic relative momenta rather than nonrelativistic values. The importance of additional terms depends upon the detailed behavior of the T matrix

Molecular equilibrium structures from experimental rotational constants and calculated vibration-rotation interaction constants

DEFF Research Database (Denmark)

Pawlowski, F; Jorgensen, P; Olsen, Jeppe

2002-01-01

A detailed study is carried out of the accuracy of molecular equilibrium geometries obtained from least-squares fits involving experimental rotational constants B(0) and sums of ab initio vibration-rotation interaction constants alpha(r)(B). The vibration-rotation interaction constants have been...... calculated for 18 single-configuration dominated molecules containing hydrogen and first-row atoms at various standard levels of ab initio theory. Comparisons with the experimental data and tests for the internal consistency of the calculations show that the equilibrium structures generated using Hartree......-Fock vibration-rotation interaction constants have an accuracy similar to that obtained by a direct minimization of the CCSD(T) energy. The most accurate vibration-rotation interaction constants are those calculated at the CCSD(T)/cc-pVQZ level. The equilibrium bond distances determined from these interaction...

A relativistic point coupling model for nuclear structure calculations

International Nuclear Information System (INIS)

Buervenich, T.; Maruhn, J.A.; Madland, D.G.; Reinhard, P.G.

2002-01-01

A relativistic point coupling model is discussed focusing on a variety of aspects. In addition to the coupling using various bilinear Dirac invariants, derivative terms are also included to simulate finite-range effects. The formalism is presented for nuclear structure calculations of ground state properties of nuclei in the Hartree and Hartree-Fock approximations. Different fitting strategies for the determination of the parameters have been applied and the quality of the fit obtainable in this model is discussed. The model is then compared more generally to other mean-field approaches both formally and in the context of applications to ground-state properties of known and superheavy nuclei. Perspectives for further extensions such as an exact treatment of the exchange terms using a higher-order Fierz transformation are discussed briefly. (author)

β-decay rates of r-process nuclei in the relativistic quasiparticle random phase approximation

International Nuclear Information System (INIS)

Niksic, T.; Marketin, T.; Vretenar, D.; Paar, N.; Ring, P.

2004-01-01

The fully consistent relativistic proton-neutron quasiparticle random phase approximation (PN-RQRPA) is employed in the calculation of β-decay half-lives of neutron-rich nuclei in the N∼50 and N∼82 regions. A new density-dependent effective interaction, with an enhanced value of the nucleon effective mass, is used in relativistic Hartree-Bogolyubov calculation of nuclear ground states and in the particle-hole channel of the PN-RQRPA. The finite range Gogny D1S interaction is employed in the T=1 pairing channel, and the model also includes a proton-neutron particle-particle interaction. The theoretical half-lives reproduce the experimental data for the Fe, Zn, Cd, and Te isotopic chains, but overestimate the lifetimes of Ni isotopes and predict a stable 132 Sn. (orig.)

{beta}-decay rates of r-process nuclei in the relativistic quasiparticle random phase approximation

Energy Technology Data Exchange (ETDEWEB)

Niksic, T.; Marketin, T.; Vretenar, D. [Zagreb Univ. (Croatia). Faculty of Science, Physics Dept.; Paar, N. [Technische Univ. Darmstadt (Germany). Inst. fuer Kernphysik; Ring, P. [Technische Univ. Muenchen, Garching (Germany). Physik-Department

2004-12-08

The fully consistent relativistic proton-neutron quasiparticle random phase approximation (PN-RQRPA) is employed in the calculation of {beta}-decay half-lives of neutron-rich nuclei in the N{approx}50 and N{approx}82 regions. A new density-dependent effective interaction, with an enhanced value of the nucleon effective mass, is used in relativistic Hartree-Bogolyubov calculation of nuclear ground states and in the particle-hole channel of the PN-RQRPA. The finite range Gogny D1S interaction is employed in the T=1 pairing channel, and the model also includes a proton-neutron particle-particle interaction. The theoretical half-lives reproduce the experimental data for the Fe, Zn, Cd, and Te isotopic chains, but overestimate the lifetimes of Ni isotopes and predict a stable {sup 132}Sn. (orig.)

Relativistic meson spectroscopy in momentum space

International Nuclear Information System (INIS)

Hersbach, H.

1994-01-01

In this paper a relativistic constituent-quark model based on the Ruijgrok--de Groot formalism is presented. The quark model is not defined in configuration space, but in momentum space. The complete meson spectrum, with the exception of the self-conjugate light unflavored mesons, is calculated. The potential used consists of a one-gluon exchange (OGE) part and a confining part. For the confining part a relativistic generalization of the linear plus constant potential was used, which is well defined in momentum space without introducing any singularities. For the OGE part several potentials were investigated. Retardations were included at all places. By the use of a fitting procedure involving 52 well-established mesons, but results were obtained for a potential consisting of a purely vector Richardson potential and a purely scalar confining potential. Reasonable results were also obtained for a modified Richardson potential. Most meson masses, with the exception of the π, the K, and the K 0 * , were found to be quite well described by the model

Multi-configuration Dirac-Hartree-Fock (MCDHF) calculations for Ni XXV

Science.gov (United States)

Singh, Narendra; Aggarwal, Sunny

2018-03-01

We present accurate 165 fine-structure energy levels related to the configurations 1s22s2, 1s22p2, 1s2nƖn‧l‧ (n = 2, n‧ = 2, 3, 4, 5, Ɩ = s,p Ɩ‧ = s, p, d, f, g) of Ni XXV which may be useful ion for astrophysical and fusion plasma. For the calculations of energy levels and radiative rates, we have used the multiconfiguration Dirac-Hartree-Fock (MCDHF) method employed in GRASP2K code. The calculations are carried out in the active space approximation with the inclusion of the Breit interaction, the finite nuclear size effect, and quantum electrodynamic corrections. The transition wavelengths, transition probabilities, line strengths, and absorption oscillator strengths are reported for electric dipole (E1), electric quadrupole (E2), magnetic dipole (M1), magnetic quadrupole (M2) transitions from the ground state. We have compared our calculated results with available theoretical and experimental data and good agreement is achieved. We predict new energy levels, oscillator strengths, line strengths and transition probabilities, where no other experimental or theoretical results are available. The present complete set of results should be of great help in line identification and the interpretation of spectra, as well as in the modelling and diagnostics of astrophysical and fusion plasmas.

Parallel multireference configuration interaction calculations on mini-beta-carotenes and beta-carotene.

Science.gov (United States)

Kleinschmidt, Martin; Marian, Christel M; Waletzke, Mirko; Grimme, Stefan

2009-01-28

We present a parallelized version of a direct selecting multireference configuration interaction (MRCI) code [S. Grimme and M. Waletzke, J. Chem. Phys. 111, 5645 (1999)]. The program can be run either in ab initio mode or as semiempirical procedure combined with density functional theory (DFT/MRCI). We have investigated the efficiency of the parallelization in case studies on carotenoids and porphyrins. The performance is found to depend heavily on the cluster architecture. While the speed-up on the older Intel Netburst technology is close to linear for up to 12-16 processes, our results indicate that it is not favorable to use all cores of modern Intel Dual Core or Quad Core processors simultaneously for memory intensive tasks. Due to saturation of the memory bandwidth, we recommend to run less demanding tasks on the latter architectures in parallel to two (Dual Core) or four (Quad Core) MRCI processes per node. The DFT/MRCI branch has been employed to study the low-lying singlet and triplet states of mini-n-beta-carotenes (n=3, 5, 7, 9) and beta-carotene (n=11) at the geometries of the ground state, the first excited triplet state, and the optically bright singlet state. The order of states depends heavily on the conjugation length and the nuclear geometry. The (1)B(u) (+) state constitutes the S(1) state in the vertical absorption spectrum of mini-3-beta-carotene but switches order with the 2 (1)A(g) (-) state upon excited state relaxation. In the longer carotenes, near degeneracy or even root flipping between the (1)B(u) (+) and (1)B(u) (-) states is observed whereas the 3 (1)A(g) (-) state is found to remain energetically above the optically bright (1)B(u) (+) state at all nuclear geometries investigated here. The DFT/MRCI method is seen to underestimate the absolute excitation energies of the longer mini-beta-carotenes but the energy gaps between the excited states are reproduced well. In addition to singlet data, triplet-triplet absorption energies are

Parallel multireference configuration interaction calculations on mini-β-carotenes and β-carotene

Science.gov (United States)

Kleinschmidt, Martin; Marian, Christel M.; Waletzke, Mirko; Grimme, Stefan

2009-01-01

We present a parallelized version of a direct selecting multireference configuration interaction (MRCI) code [S. Grimme and M. Waletzke, J. Chem. Phys. 111, 5645 (1999)]. The program can be run either in ab initio mode or as semiempirical procedure combined with density functional theory (DFT/MRCI). We have investigated the efficiency of the parallelization in case studies on carotenoids and porphyrins. The performance is found to depend heavily on the cluster architecture. While the speed-up on the older Intel Netburst technology is close to linear for up to 12-16 processes, our results indicate that it is not favorable to use all cores of modern Intel Dual Core or Quad Core processors simultaneously for memory intensive tasks. Due to saturation of the memory bandwidth, we recommend to run less demanding tasks on the latter architectures in parallel to two (Dual Core) or four (Quad Core) MRCI processes per node. The DFT/MRCI branch has been employed to study the low-lying singlet and triplet states of mini-n-β-carotenes (n =3, 5, 7, 9) and β-carotene (n =11) at the geometries of the ground state, the first excited triplet state, and the optically bright singlet state. The order of states depends heavily on the conjugation length and the nuclear geometry. The B1u+ state constitutes the S1 state in the vertical absorption spectrum of mini-3-β-carotene but switches order with the 2 A1g- state upon excited state relaxation. In the longer carotenes, near degeneracy or even root flipping between the B1u+ and B1u- states is observed whereas the 3 A1g- state is found to remain energetically above the optically bright B1u+ state at all nuclear geometries investigated here. The DFT/MRCI method is seen to underestimate the absolute excitation energies of the longer mini-β-carotenes but the energy gaps between the excited states are reproduced well. In addition to singlet data, triplet-triplet absorption energies are presented. For β-carotene, where these transition

Relativistic neoclassical transport coefficients with momentum correction

International Nuclear Information System (INIS)

Marushchenko, I.; Azarenkov, N.A.

2016-01-01

The parallel momentum correction technique is generalized for relativistic approach. It is required for proper calculation of the parallel neoclassical flows and, in particular, for the bootstrap current at fusion temperatures. It is shown that the obtained system of linear algebraic equations for parallel fluxes can be solved directly without calculation of the distribution function if the relativistic mono-energetic transport coefficients are already known. The first relativistic correction terms for Braginskii matrix coefficients are calculated.

A unified treatment of the non-relativistic and relativistic hydrogen atom: Pt. 2

International Nuclear Information System (INIS)

Swainson, R.A.; Drake, G.W.F.

1991-01-01

This is the second in a series of three papers in which it is shown how the radial part of non-relativistic and relativistic hydrogenic bound-state calculations involving the Green functions can be presented in a unified manner. In this paper the non-relativistic Green function is examined in detail; new functional forms are presented and a clear mathematical progression is show to link these and most other known forms. A linear transformation of the four radial parts of the relativistic Green function is given which allows for the presentation of this function as a simple generalization of the non-relativistic Green function. Thus, many properties of the non-relativistic Green function are shown to have simple relativistic generalizations. In particular, new recursion relations of the radial parts of both the non-relativistic and relativistic Green functions are presented, along with new expressions for the double Laplace transforms and recursion relations between the radial matrix elements. (author)

LATTICE SIMULATIONS OF THE THERMODYNAMICS OF STRONGLY INTERACTING ELEMENTARY PARTICLES AND THE EXPLORATION OF NEW PHASES OF MATTER IN RELATIVISTIC HEAVY ION COLLISIONS

International Nuclear Information System (INIS)

KARSCH, F.

2006-01-01

At high temperatures or densities matter formed by strongly interacting elementary particles (hadronic matter) is expected to undergo a transition to a new form of matter--the quark gluon plasma--in which elementary particles (quarks and gluons) are no longer confined inside hadrons but are free to propagate in a thermal medium much larger in extent than the typical size of a hadron. The transition to this new form of matter as well as properties of the plasma phase are studied in large scale numerical calculations based on the theory of strong interactions--Quantum Chromo Dynamics (QCD). Experimentally properties of hot and dense elementary particle matter are studied in relativistic heavy ion collisions such as those currently performed at the relativistic heavy ion collider (RHIC) at BNL. We review here recent results from studies of thermodynamic properties of strongly interacting elementary particle matter performed on Teraflops-Computer. We present results on the QCD equation of state and discuss the status of studies of the phase diagram at non-vanishing baryon number density

Inductive and electrostatic acceleration in relativistic jet-plasma interactions.

Science.gov (United States)

Ng, Johnny S T; Noble, Robert J

2006-03-24

We report on the observation of rapid particle acceleration in numerical simulations of relativistic jet-plasma interactions and discuss the underlying mechanisms. The dynamics of a charge-neutral, narrow, electron-positron jet propagating through an unmagnetized electron-ion plasma was investigated using a three-dimensional, electromagnetic, particle-in-cell computer code. The interaction excited magnetic filamentation as well as electrostatic plasma instabilities. In some cases, the longitudinal electric fields generated inductively and electrostatically reached the cold plasma-wave-breaking limit, and the longitudinal momentum of about half the positrons increased by 50% with a maximum gain exceeding a factor of 2 during the simulation period. Particle acceleration via these mechanisms occurred when the criteria for Weibel instability were satisfied.

Electronic structure of FeTiSb using relativistic and scalar-relativistic approaches

Energy Technology Data Exchange (ETDEWEB)

Sahariya, Jagrati [Department of Physics, Manipal University Jaipur, Jaipur-303007, Rajasthan (India); Mund, H. S., E-mail: hmoond@gmail.com [Department of Physics, M. L. Sukhadia University, Udaipur-313001, Rajasthan (India)

2016-05-06

Electronic and magnetic properties of FeTiSb have been reported. The calculations are performed using spin polarized relativistic Korringa-Kohn-Rostoker scheme based on Green’s function method. Within SPR-KKR a fully relativistic and scalar-relativistic approaches have been used to investigate electronic structure of FeTiSb. Energy bands, total and partial density of states, atom specific magnetic moment along with total moment of FeTiSb alloys are presented.

An introduction to relativistic processes and the standard model of electroweak interactions

CERN Document Server

Becchi, Carlo Maria

2006-01-01

These notes are designed as a guide-line for a course in Elementary Particle Physics for undergraduate students. The purpose is providing a rigorous and self-contained presentation of the theoretical framework and of the phenomenological aspects of the physics of interactions among fundamental constituents of matter. The first part of the volume is devoted to the description of scattering processes in the context of relativistic quantum field theory. The use of the semi-classical approximation allows us to illustrate the relevant computation techniques in a reasonably small amount of space. Our approach to relativistic processes is original in many respects. The second part contains a detailed description of the construction of the standard model of electroweak interactions, with special attention to the mechanism of particle mass generation. The extension of the standard model to include neutrino masses is also described. We have included a number of detailed computations of cross sections and decay rates of...

Comparison of different boost transformations for the calculation of form factors in relativistic quantum mechanics

International Nuclear Information System (INIS)

Theussl, L.; Noguera, S.; Amghar, A.; Desplanques, B.

2003-01-01

The effect of different boost expressions, pertinent to the instant, front and point forms of relativistic quantum mechanics, is considered for the calculation of the ground-state form factor of a two-body system in simple scalar models. Results with a Galilean boost as well as an explicitly covariant calculation based on the Bethe-Salpeter approach are given for comparison. It is found that the present so-called point-form calculations of form factors strongly deviate from all the other ones. This suggests that the formalism which underlies them requires further elaboration. A proposition in this sense is made. (author)

Relativistic many-body theory of atomic transitions. The relativistic equation-of-motion approach

International Nuclear Information System (INIS)

Huang, K.

1982-01-01

An equation-of-motion approach is used to develop the relativistic many-body theory of atomic transitions. The relativistic equations of motion for transition matrices are formulated with the use of techniques of quantum-field theory. To reduce the equations of motion to a tractable form which is appropriate for numerical calculations, a graphical method to resolve the complication arising from the antisymmetrization and angular-momentum coupling is employed. The relativistic equation-of-motion method allows an ab initio treatment of correlation and relativistic effects in both closed- and open-shell many-body systems. A special case of the present formulation reduces to the relativistic random-phase approximation

Relativistic many-body theory of atomic transitions: the relativistic equation-of-motion approach

International Nuclear Information System (INIS)

Huang, K.N.

1981-01-01

An equation-of-motion approach is used to develop the relativistic many-body theory of atomic transitions. The relativistic equations of motion for transition matrices are formulated using techniques of quantum field theory. To reduce the equation of motion to a tractable form which is appropriate for numerical calculations, a graphical method is employed to resolve the complication arising from the antisymmetrization and angular momentum coupling. The relativistic equation-of-motion method allows an ab initio treatment of correlation and relativistic effects in both closed- and open-shell many-body systems. A special case of the present formulation reduces to the relativistic random-phase approximation

Near-threshold photoionization of the Xe 3d spin-orbit doublet: Relativistic, relaxation, and intershell interaction effects

International Nuclear Information System (INIS)

Radojevic, V.; Davidovic, D.M.; Amusia, M.Ya.

2003-01-01

Results of calculations of the near-threshold photoionization of the xenon 3d spin-orbit doublet are reported. Our theoretical analysis is undertaken in order to interpret and enlighten the very detailed measurements of this process [A. Kivimaeki et al., Phys. Rev. A 63, 012716 (2001)], which revealed a previously unobserved interesting feature--an additional broad maximum--in the partial xenon 3d 5/2 cross section. This double maximum was not produced by earlier calculations, except in the recent study by Amusia et al. [Phys. Rev. Lett. 88, 093002 (2002)], which, in contrast to the present one, is not ab initio and relativistic in character. The partial photoionization cross sections of 3d 5/2 and 3d 3/2 subshells, photoelectron anisotropy parameters, and spin-polarization parameters that were so far not studied either experimentally or theoretically are calculated. Many-electron correlations, relativistic effects, and relaxation effects of the ionic core in the ionization process are taken into account by using the relativistic random-phase approximation, modified to include the relaxation of the considered subshell

Improving the Performance of Interactive Configuration with Regular String Constraints

DEFF Research Database (Denmark)

Hansen, Esben Rune; Tiedemann, Peter

2008-01-01

A generalization of the problem of interactive configuration has previously been presented in [1]. This generalization utilized decomposition to extend the standard finite domain interactive configuration framework to deal with unbounded string variables and provided features such as prefix auto...

Relativistic quantum mechanics; Mecanique quantique relativiste

Energy Technology Data Exchange (ETDEWEB)

Ollitrault, J.Y. [CEA Saclay, 91 - Gif-sur-Yvette (France). Service de Physique Theorique]|[Universite Pierre et Marie Curie, 75 - Paris (France)

1998-12-01

These notes form an introduction to relativistic quantum mechanics. The mathematical formalism has been reduced to the minimum in order to enable the reader to calculate elementary physical processes. The second quantification and the field theory are the logical followings of this course. The reader is expected to know analytical mechanics (Lagrangian and Hamiltonian), non-relativistic quantum mechanics and some basis of restricted relativity. The purpose of the first 3 chapters is to define the quantum mechanics framework for already known notions about rotation transformations, wave propagation and restricted theory of relativity. The next 3 chapters are devoted to the application of relativistic quantum mechanics to a particle with 0,1/5 and 1 spin value. The last chapter deals with the processes involving several particles, these processes require field theory framework to be thoroughly described. (A.C.) 2 refs.

Relativistic Normal Coupled-Cluster Theory for Accurate Determination of Electric Dipole Moments of Atoms: First Application to the ^{199}Hg Atom.

Science.gov (United States)

Sahoo, B K; Das, B P

2018-05-18

Recent relativistic coupled-cluster (RCC) calculations of electric dipole moments (EDMs) of diamagnetic atoms due to parity and time-reversal violating (P,T-odd) interactions, which are essential ingredients for probing new physics beyond the standard model of particle interactions, differ substantially from the previous theoretical results. It is therefore necessary to perform an independent test of the validity of these results. In view of this, the normal coupled-cluster method has been extended to the relativistic regime [relativistic normal coupled-cluster (RNCC) method] to calculate the EDMs of atoms by simultaneously incorporating the electrostatic and P,T-odd interactions in order to overcome the shortcomings of the ordinary RCC method. This new relativistic method has been applied to ^{199}Hg, which currently has a lower EDM limit than that of any other system. The results of our RNCC and self-consistent RCC calculations of the EDM of this atom are found to be close. The discrepancies between these two results on the one hand and those of previous calculations on the other are elucidated. Furthermore, the electric dipole polarizability of this atom, which has computational similarities with the EDM, is evaluated and it is in very good agreement with its measured value.

Relativistic Normal Coupled-Cluster Theory for Accurate Determination of Electric Dipole Moments of Atoms: First Application to the 199Hg Atom

Science.gov (United States)

Sahoo, B. K.; Das, B. P.

2018-05-01

Recent relativistic coupled-cluster (RCC) calculations of electric dipole moments (EDMs) of diamagnetic atoms due to parity and time-reversal violating (P ,T -odd) interactions, which are essential ingredients for probing new physics beyond the standard model of particle interactions, differ substantially from the previous theoretical results. It is therefore necessary to perform an independent test of the validity of these results. In view of this, the normal coupled-cluster method has been extended to the relativistic regime [relativistic normal coupled-cluster (RNCC) method] to calculate the EDMs of atoms by simultaneously incorporating the electrostatic and P ,T -odd interactions in order to overcome the shortcomings of the ordinary RCC method. This new relativistic method has been applied to 199Hg, which currently has a lower EDM limit than that of any other system. The results of our RNCC and self-consistent RCC calculations of the EDM of this atom are found to be close. The discrepancies between these two results on the one hand and those of previous calculations on the other are elucidated. Furthermore, the electric dipole polarizability of this atom, which has computational similarities with the EDM, is evaluated and it is in very good agreement with its measured value.

Halo nuclei studied by relativistic mean-field approach

International Nuclear Information System (INIS)

Gmuca, S.

1997-01-01

Density distributions of light neutron-rich nuclei are studied by using the relativistic mean-field approach. The effective interaction which parameterizes the recent Dirac-Brueckner-Hartree-Fock calculations of nuclear matter is used. The results are discussed and compared with the experimental observations with special reference to the neutron halo in the drip-line nuclei. (author)

Auroral kilometric radiation - An example of relativistic wave-particle interaction in geoplasma

International Nuclear Information System (INIS)

Pritchett, P.L.

1990-01-01

The earth's auroral kilometric radiation (AKR) is believed to be produced by the electron-cyclotron maser instability. This instability is the result of a wave-particle interaction in which relativistic effects are crucial. An explanation is given as to how these relativistic effects alter the shape of the resonance curve in velocity space and modify the R - X mode wave dispersion near the electron cyclotron frequency compared to the results obtained in the nonrelativistic limit and from cold-plasma theory. The properties of the cyclotron maser instability in a driven system are illustrated using two-dimensional electromagnetic particle simulations which incorporate a continual flow of primary energetic electrons along the magnetic field. 31 refs

Configuration interaction wave functions: A seniority number approach

International Nuclear Information System (INIS)

Alcoba, Diego R.; Torre, Alicia; Lain, Luis; Massaccesi, Gustavo E.; Oña, Ofelia B.

2014-01-01

This work deals with the configuration interaction method when an N-electron Hamiltonian is projected on Slater determinants which are classified according to their seniority number values. We study the spin features of the wave functions and the size of the matrices required to formulate states of any spin symmetry within this treatment. Correlation energies associated with the wave functions arising from the seniority-based configuration interaction procedure are determined for three types of molecular orbital basis: canonical molecular orbitals, natural orbitals, and the orbitals resulting from minimizing the expectation value of the N-electron seniority number operator. The performance of these bases is analyzed by means of numerical results obtained from selected N-electron systems of several spin symmetries. The comparison of the results highlights the efficiency of the molecular orbital basis which minimizes the mean value of the seniority number for a state, yielding energy values closer to those provided by the full configuration interaction procedure

Configuration interaction wave functions: A seniority number approach

Energy Technology Data Exchange (ETDEWEB)

Alcoba, Diego R. [Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and Instituto de Física de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Universitaria, 1428 Buenos Aires (Argentina); Torre, Alicia; Lain, Luis, E-mail: qfplapel@lg.ehu.es [Departamento de Química Física, Facultad de Ciencia y Tecnología, Universidad del País Vasco, Apdo. 644, E-48080 Bilbao (Spain); Massaccesi, Gustavo E. [Departamento de Ciencias Exactas, Ciclo Básico Común, Universidad de Buenos Aires, Ciudad Universitaria, 1428 Buenos Aires (Argentina); Oña, Ofelia B. [Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas, Universidad Nacional de La Plata, CCT La Plata, Consejo Nacional de Investigaciones Científicas y Técnicas, Diag. 113 y 64 (S/N), Sucursal 4, CC 16, 1900 La Plata (Argentina)

2014-06-21

This work deals with the configuration interaction method when an N-electron Hamiltonian is projected on Slater determinants which are classified according to their seniority number values. We study the spin features of the wave functions and the size of the matrices required to formulate states of any spin symmetry within this treatment. Correlation energies associated with the wave functions arising from the seniority-based configuration interaction procedure are determined for three types of molecular orbital basis: canonical molecular orbitals, natural orbitals, and the orbitals resulting from minimizing the expectation value of the N-electron seniority number operator. The performance of these bases is analyzed by means of numerical results obtained from selected N-electron systems of several spin symmetries. The comparison of the results highlights the efficiency of the molecular orbital basis which minimizes the mean value of the seniority number for a state, yielding energy values closer to those provided by the full configuration interaction procedure.

Calculation of the binding energy per nucleon and the quasi-particle interation in nuclear matter under consideration of relativistic medium effects

International Nuclear Information System (INIS)

Hippchen, T.

1985-12-01

In a first part, nuclear matter calculations have been performed in the Dirac-Brueckner approach using a) a nucleon-nucleon potential of one-boson-exchange (OBE) type and b) a more realistic interaction in which the fictitious σ-exchange of the OBE-model is replaced by explicit 2π- and πρ-exchange diagrams. Both potential models yield the correct empirical binding energy and saturation density. It turns out that the total sum of relativistic effects caused by the emplicit 2 π- and πρ-exchanges is comparable to those due to σ-exchange. In a second part, the nuclear quasiparticle interaction, i.e. the Landau parameters, have been calculated in the central (F), isospin (F'), spin (G) and spin-isospin (G') channel, in an analogous way. Compared to nonrelativistic calculations (including conventional medium corrections like Pauli and dispersion effects), a strong improvement has been found, especially in the F- and G-channel. Finally, the influence of A 1 -exchange is studied, in NN scattering and in nuclear matter. It turns out that, after a suitable and necessary readjustment of some meson parameters, its role is negligibly small. (orig.)

Selectivity of the nucleon-induced deuteron breakup and relativistic effects

OpenAIRE

Witała, H.; Golak, J.; Skibiński, R.

2006-01-01

Theoretical predictions for the nucleon induced deuteron breakup process based on solutions of the three-nucleon Faddeev equation including such relativistic features as the relativistic kinematics and boost effects are presented. Large changes of the breakup cross section in some complete configurations are found at higher energies. The predicted relativistic effects, which are mostly of dynamical origin, seem to be supported by existing data.

Pushing configuration-interaction to the limit

DEFF Research Database (Denmark)

Vogiatzis, Konstantinos D.; Ma, Dongxia; Olsen, Jeppe

2017-01-01

A new large-scale parallel multiconfigurational self-consistent field (MCSCF) implementation in the open-source NWChem computational chemistry code is presented. The generalized active space (GAS) approach is used to partition large configuration interaction (CI) vectors and generate a sufficient...

Calculation of radiative opacity of plasma mixtures using a relativistic screened hydrogenic model

International Nuclear Information System (INIS)

Mendoza, M.A.; Rubiano, J.G.; Gil, J.M.; Rodríguez, R.; Florido, R.; Espinosa, G.; Martel, P.; Mínguez, E.

2014-01-01

We present the code ATMED based on an average atom model and conceived for fast computing the population distribution and radiative properties of hot and dense single and multicomponent plasmas under LTE conditions. A relativistic screened hydrogenic model (RSHM), built on a new set of universal constants considering j-splitting, is used to calculate the required atomic data. The opacity model includes radiative bound–bound, bound–free, free–free, and scattering processes. Bound–bound line-shape function has contributions from natural, Doppler and electron-impact broadenings. An additional dielectronic broadening to account for fluctuations in the average level populations has been included, which improves substantially the Rosseland mean opacity results. To illustrate the main features of the code and its capabilities, calculations of several fundamental quantities of one-component plasmas and mixtures are presented, and a comparison with previously published data is performed. Results are satisfactorily compared with those predicted by more elaborate codes. - Highlights: • A new opacity code, ATMED, based on the average atom approximation is presented. • Atomic data are computed by means of a relativistic screened hydrogenic model. • An effective bound level degeneracy is included for accounting pressure ionization. • A new dielectronic line broadening is included to improve the mean opacities. • ATMED has the possibility to handle with single element and multicomponent plasmas

Relativistic scalar-vector models of the N-N and N-nuclear interactions

International Nuclear Information System (INIS)

Green, A.E.S.

1985-01-01

This paper for the Proceedings of Conference an Anti-Nucleon and Nucleon-Nucleus Interactions summarizes work by the principal investigator and his collaborators on the nucleon-nucleon (N-N) and nucleon-nuclear (N-eta) interactions. It draws heavily on a paper presented at the Many Body Conference in Rome in 1972 but also includes a brief review of our phenomenological N-eta interaction studies. We first summarize our 48-49 generalized scalar-vector meson field theory model of the N-N interactions. This is followed by a brief description of our phenomenological work in the 50's on the N-eta interaction sponsored by the Atomic Energy Commission (the present DOE). This work finally led to strong velocity dependent potentials with spin orbit and isospin terms for shell and optical model applications. This is followed by a section on the Emergence of One-Boson Exchange Models describing developments in the 60's of quantitative generalized one boson exchange potentials (GOBEP) including our purely relativistic N-N analyses. Then follows a section on the application of this meson field model to the N-eta interaction, in particular to spherical closed shell nuclei. This work was sponsored by AFOSR but funding was halted with the Mansfield amendment. We conclude with a discussion of subsequent collateral work by former colleagues and by others who have converged upon scalar-vector relativistic models of N-N, antiN-N, N-eta and antiN-eta interactions and some lessons learned from this extended endeavor. 61 refs

Spectral analysis of 5s25p2(6p+6d+7s) configurations of Ba VI

International Nuclear Information System (INIS)

Sharma, M.K.; Tauheed, A.; Rahimullah, K.

2014-01-01

The sixth spectrum of barium (Ba VI) has been investigated with the aid of experimental recordings made on a 3-m normal incidence vacuum spectrograph of Antigonish laboratory (Canada) in the wavelength region 300–2080 Å using triggered spark as an excitation source. The spectral analysis has been extended considerably to include new configuration the 5s 2 5p 2 6p in odd parity matrix and the 5s 2 5p 2 6d and 5s 2 5p 2 7s configurations in even parity matrix. Previously reported levels of the ground configuration (5s 2 5p 3 ) and three lowest excited configurations the 5s5p 4 , 5s 2 5p 2 5d and 5s 2 5p 2 6s have been confirmed and the two unknown levels of the 5s 2 5p 2 5d configuration with J=9/2, have now been established through the identification of transitions from the 5s 2 5p 2 6p levels. All twenty one levels of the 5s 2 5p 2 6p configuration and twenty nine levels out of thirty six of the 5s 2 5p 2 6d and 5s 2 5p 2 7s configurations have now been established. Hartree–Fock calculations involving configuration interactions support the analyses. The accuracy of our wavelength measurement is ±0.005 Å for sharp lines. - Highlights: • The spectrum of Ba was recorded on a 3-m spectrograph with triggered spark source. • Atomic transitions for Ba VI were identified to established new energy levels. • CI calculations with relativistic corrections were made for theoretical predictions. • Weighted oscillator strength (gf) and transition probabilities (gA) were calculated

Non-Hermitian interaction representation and its use in relativistic quantum mechanics

Czech Academy of Sciences Publication Activity Database

Znojil, Miloslav

2017-01-01

Roč. 385, č. 10 (2017), s. 162-179 ISSN 0003-4916 R&D Projects: GA ČR GA16-22945S Institutional support: RVO:61389005 Keywords : unitary quantum systems * non-Hermitian version of Dirac's interaction picture * complete set of time-evolution equations * application in relativistic quantum mechanics * Klein-Gordon example with space-time-dependent mass Subject RIV: BE - Theoretical Physics OBOR OECD: Atomic, molecular and chemical physics ( physics of atoms and molecules including collision, interaction with radiation, magnetic resonances, Mössbauer effect) Impact factor: 2.465, year: 2016

Study of nonlinear interaction between bunched beam and intermediate cavities in a relativistic klystron amplifier

Energy Technology Data Exchange (ETDEWEB)

Wu, Y. [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Institute of Applied Electronics, China Academy of Engineering Physics, Mianyang 621900 (China); Science and Technology on High Power Microwave Laboratory, Mianyang 621900 (China); Xu, Z.; Li, Z. H. [Institute of Applied Electronics, China Academy of Engineering Physics, Mianyang 621900 (China); Tang, C. X. [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China)

2012-07-15

In intermediate cavities of a relativistic klystron amplifier (RKA) driven by intense relativistic electron beam, the equivalent circuit model, which is widely adopted to investigate the interaction between bunched beam and the intermediate cavity in a conventional klystron design, is invalid due to the high gap voltage and the nonlinear beam loading in a RKA. According to Maxwell equations and Lorentz equation, the self-consistent equations for beam-wave interaction in the intermediate cavity are introduced to study the nonlinear interaction between bunched beam and the intermediate cavity in a RKA. Based on the equations, the effects of modulation depth and modulation frequency of the beam on the gap voltage amplitude and its phase are obtained. It is shown that the gap voltage is significantly lower than that estimated by the equivalent circuit model when the beam modulation is high. And the bandwidth becomes wider as the beam modulation depth increases. An S-band high gain relativistic klystron amplifier is designed based on the result. And the corresponding experiment is carried out on the linear transformer driver accelerator. The peak output power has achieved 1.2 GW with an efficiency of 28.6% and a gain of 46 dB in the corresponding experiment.

Study of nonlinear interaction between bunched beam and intermediate cavities in a relativistic klystron amplifier

Science.gov (United States)

Wu, Y.; Xu, Z.; Li, Z. H.; Tang, C. X.

2012-07-01

In intermediate cavities of a relativistic klystron amplifier (RKA) driven by intense relativistic electron beam, the equivalent circuit model, which is widely adopted to investigate the interaction between bunched beam and the intermediate cavity in a conventional klystron design, is invalid due to the high gap voltage and the nonlinear beam loading in a RKA. According to Maxwell equations and Lorentz equation, the self-consistent equations for beam-wave interaction in the intermediate cavity are introduced to study the nonlinear interaction between bunched beam and the intermediate cavity in a RKA. Based on the equations, the effects of modulation depth and modulation frequency of the beam on the gap voltage amplitude and its phase are obtained. It is shown that the gap voltage is significantly lower than that estimated by the equivalent circuit model when the beam modulation is high. And the bandwidth becomes wider as the beam modulation depth increases. An S-band high gain relativistic klystron amplifier is designed based on the result. And the corresponding experiment is carried out on the linear transformer driver accelerator. The peak output power has achieved 1.2 GW with an efficiency of 28.6% and a gain of 46 dB in the corresponding experiment.

On the electronic structure of 5g1 complexes of element 125: a quasi - relativistic MS-Xα study

International Nuclear Information System (INIS)

Makhyoun, M.A.

1988-01-01

Quasi-relativistic SCF Xα calculations are reported for the hypothetical complexes E0 2 2+ , EF 6 (E = element 125) and the 5f 1 ion Np0 2 2 + . The calculations indicate that the E complexes have a 5g 1 outer electronic configuration with good agreement with previous predictions. The ligand field energy diagram for G 1 system in 0 h symmetry in discussed in relation to the obtained X α results

Hard processes and fragmentation in a unified model for interactions at ultra-relativistic energies; Les processus durs et la fragmentation dans un modele unifie pour les interactions aux energies ultra-relativistes

Energy Technology Data Exchange (ETDEWEB)

Drescher, H.J

1999-06-11

In this work we have developed hard processes and string fragmentation in the framework of interactions at relativistic energies. The hypothesis of the universality of high energy interactions means that many elements of heavy ion collisions can be studied and simulated in simpler nuclear reactions. In particular this hypothesis implies that the fragmentation observed in the reaction e{sup +}e{sup -} follows the same rules as in the collision of 2 lead ions. This work deals with 2 nuclear processes: the e{sup +}e{sup -} annihilation reaction and the deep inelastic diffusion. For the first process the string model has been developed to simulate fragmentation by adding an artificial breaking of string due to relativistic effects. A monte-Carlo method has been used to determine the points in a Minkowski space where this breaking occurs. For the second reaction, the theory of semi-hard pomerons is introduced in order to define elementary hadron-hadron interactions. The model of fragmentation proposed in this work can be applied to more complicated reactions such as proton-proton or ion-ion collisions.

Calculated nuclide production yields in relativistic collisions of fissile nuclei

Energy Technology Data Exchange (ETDEWEB)

Benlliure, J.; Schmidt, K.H. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Grewe, A.; Jong, M. de [Technische Univ. Darmstadt (Germany). Inst. fuer Kernphysik; Zhdanov, S. [AN Kazakhskoj SSR, Alma-Ata (USSR). Inst. Yadernoj Fiziki

1997-11-01

A model calculation is presented which predicts the complex nuclide distribution resulting from peripheral relativistic heavy-ion collisions involving fissile nuclei. The model is based on a modern version of the abrasion-ablation model which describes the formation of excited prefragments due to the nuclear collisions and their consecutive decay. The competition between the evaporation of different light particles and fission is computed with an evaporation code which takes dissipative effects and the emission of intermediate-mass fragments into account. The nuclide distribution resulting from fission processes is treated by a semiempirical description which includes the excitation-energy dependent influence of nuclear shell effects and pairing correlations. The calculations of collisions between {sup 238}U and different reaction partners reveal that a huge number of isotopes of all elements up to uranium is produced. The complex nuclide distribution shows the characteristics of fragmentation, mass-asymmetric low-energy fission and mass-symmetric high-energy fission. The yields of the different components for different reaction partners are studied. Consequences for technical applications are discussed. (orig.)

Relativistic quantum mechanics and introduction to field theory

Energy Technology Data Exchange (ETDEWEB)

Yndurain, F.J. [Universidad Autonoma de Madrid (Spain). Dept. de Fisica Teorica

1996-12-01

The following topics were dealt with: relativistic transformations, the Lorentz group, Klein-Gordon equation, spinless particles, spin 1/2 particles, Dirac particle in a potential, massive spin 1 particles, massless spin 1 particles, relativistic collisions, S matrix, cross sections, decay rates, partial wave analysis, electromagnetic field quantization, interaction of radiation with matter, interactions in quantum field theory and relativistic interactions with classical sources.

Relativistic quantum mechanics and introduction to field theory

International Nuclear Information System (INIS)

Yndurain, F.J.

1996-01-01

The following topics were dealt with: relativistic transformations, the Lorentz group, Klein-Gordon equation, spinless particles, spin 1/2 particles, Dirac particle in a potential, massive spin 1 particles, massless spin 1 particles, relativistic collisions, S matrix, cross sections, decay rates, partial wave analysis, electromagnetic field quantization, interaction of radiation with matter, interactions in quantum field theory and relativistic interactions with classical sources

Relativistic Coulomb Fission

Science.gov (United States)

Norbury, John W.

1992-01-01

Nuclear fission reactions induced by the electromagnetic field of relativistic nuclei are studied for energies relevant to present and future relativistic heavy ion accelerators. Cross sections are calculated for U-238 and Pu-239 fission induced by C-12, Si-28, Au-197, and U-238 projectiles. It is found that some of the cross sections can exceed 10 b.

Relativistic Shock Acceleration

International Nuclear Information System (INIS)

Duffy, P.; Downes, T.P.; Gallant, Y.A.; Kirk, J.G.

1999-01-01

In this paper we briefly review the basic theory of shock waves in relativistic hydrodynamics and magneto-hydrodynamics, emphasising some astrophysically interesting cases. We then present an overview of the theory of particle acceleration at such shocks describing the methods used to calculate the spectral indices of energetic particles. Recent results on acceleration at ultra-relativistic shocks are discussed. (author)

Nuclear Fragmentation Induced by Relativistic Projectiles Studied in the 4$\\pi$ Configuration of Plastic Track Detectors

CERN Multimedia

2002-01-01

% EMU19 \\\\ \\\\ The collisions of heavy ions at relativistic energies have been studied to explore a number of questions related with hot and dense nuclear matter in order to extend our knowledge of nuclear equation-of-state. There are other aspects of these interactions which are studied to expound the process of projectile and/or target disintegrations. The disintegrations in question could be simply binary fissions or more complex processes leading to spallation or complete fragmentation. These important aspects of nuclear reactions are prone to investigations with nuclear track detectors. \\\\ \\\\One of the comparatively new track detector materials, CR-39, is sensitive enough to record particles of Z~$\\geq$~6 with almost 100\\% efficiency up to highly relativistic energies. The wide angle acceptance and exclusive measurements possible with plastic track detectors offer an opportunity to use them in a variety of situations in which high energy charged fragments are produced. The off-line nature of measuring tra...

Relativistic corrections to η{sub c}-pair production in high energy proton–proton collisions

Energy Technology Data Exchange (ETDEWEB)

Martynenko, A.P., E-mail: a.p.martynenko@samsu.ru [Samara State University, Pavlov Street 1, 443011, Samara (Russian Federation); Samara State Aerospace University named after S.P. Korolyov, Moskovskoye Shosse 34, 443086, Samara (Russian Federation); Trunin, A.M., E-mail: amtrnn@gmail.com [Samara State Aerospace University named after S.P. Korolyov, Moskovskoye Shosse 34, 443086, Samara (Russian Federation)

2013-06-10

On the basis of perturbative QCD and the relativistic quark model we calculate relativistic corrections to the double η{sub c} meson production in proton–proton interactions at LHC energies. Relativistic terms in the production amplitude connected with the relative motion of heavy quarks and the transformation law of the bound state wave functions to the reference frame of moving charmonia are taken into account. For the gluon and quark propagators entering the amplitude we use a truncated expansion in relative quark momenta up to the second order. Relativistic corrections to the quark bound state wave functions are considered by means of the Breit-like potential. It turns out that the examined effects decrease total non-relativistic cross section more than two times and on 20 percents in the rapidity region of LHCb detector.

Relativistic magnetic reconnection driven by a moderately intense laser interacting with a micro-plasma-slab

Science.gov (United States)

Yi, Longqing; Shen, Baifei; Pukhov, Alexander; Fülöp, Tünde

2017-10-01

Magnetic reconnection (MR) in the relativistic regime is generally thought to be responsible for powering rapid bursts of non-thermal radiation in astrophysical events. It is therefore of significant importance to study how the field energy is transferred to the plasma to power the observed emission. However, due to the difficulty in making direct measurements in astrophysical systems or achieving relativistic MR in laboratory environments, the particle acceleration is usually studied using fully kinetic PIC simulations. Here we present a numerical study of a readily available (TW-mJ-class) laser interacting with a micro-scale plasma slab. The simulations show when the electron beams excited on both sides of the slab approach the end of the plasma structure, ultrafast relativistic MR occurs. As the field topology changes, the explosive release of magnetic energy results in emission of relativistic electron jets with cut-off energy 12 MeV. The proposed novel scenario can be straightforwardly implemented in experiments, and might significantly improve the understanding of fundamental questions such as field dissipation and particle acceleration in relativistic MR. This work is supported by the Knut and Alice Wallenberg Foundation and the European Research Council (ERC-2014-CoG Grant 64712).

Optimizing Sparse Matrix-Multiple Vectors Multiplication for Nuclear Configuration Interaction Calculations

Energy Technology Data Exchange (ETDEWEB)

Aktulga, Hasan Metin [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Buluc, Aydin [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Williams, Samuel [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Yang, Chao [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2014-08-14

Obtaining highly accurate predictions on the properties of light atomic nuclei using the configuration interaction (CI) approach requires computing a few extremal Eigen pairs of the many-body nuclear Hamiltonian matrix. In the Many-body Fermion Dynamics for nuclei (MFDn) code, a block Eigen solver is used for this purpose. Due to the large size of the sparse matrices involved, a significant fraction of the time spent on the Eigen value computations is associated with the multiplication of a sparse matrix (and the transpose of that matrix) with multiple vectors (SpMM and SpMM-T). Existing implementations of SpMM and SpMM-T significantly underperform expectations. Thus, in this paper, we present and analyze optimized implementations of SpMM and SpMM-T. We base our implementation on the compressed sparse blocks (CSB) matrix format and target systems with multi-core architectures. We develop a performance model that allows us to understand and estimate the performance characteristics of our SpMM kernel implementations, and demonstrate the efficiency of our implementation on a series of real-world matrices extracted from MFDn. In particular, we obtain 3-4 speedup on the requisite operations over good implementations based on the commonly used compressed sparse row (CSR) matrix format. The improvements in the SpMM kernel suggest we may attain roughly a 40% speed up in the overall execution time of the block Eigen solver used in MFDn.

Resolution-of-identity stochastic time-dependent configuration interaction for dissipative electron dynamics in strong fields.

Science.gov (United States)

Klinkusch, Stefan; Tremblay, Jean Christophe

2016-05-14

In this contribution, we introduce a method for simulating dissipative, ultrafast many-electron dynamics in intense laser fields. The method is based on the norm-conserving stochastic unraveling of the dissipative Liouville-von Neumann equation in its Lindblad form. The N-electron wave functions sampling the density matrix are represented in the basis of singly excited configuration state functions. The interaction with an external laser field is treated variationally and the response of the electronic density is included to all orders in this basis. The coupling to an external environment is included via relaxation operators inducing transition between the configuration state functions. Single electron ionization is represented by irreversible transition operators from the ionizing states to an auxiliary continuum state. The method finds its efficiency in the representation of the operators in the interaction picture, where the resolution-of-identity is used to reduce the size of the Hamiltonian eigenstate basis. The zeroth-order eigenstates can be obtained either at the configuration interaction singles level or from a time-dependent density functional theory reference calculation. The latter offers an alternative to explicitly time-dependent density functional theory which has the advantage of remaining strictly valid for strong field excitations while improving the description of the correlation as compared to configuration interaction singles. The method is tested on a well-characterized toy system, the excitation of the low-lying charge transfer state in LiCN.

Resolution-of-identity stochastic time-dependent configuration interaction for dissipative electron dynamics in strong fields

Energy Technology Data Exchange (ETDEWEB)

Klinkusch, Stefan; Tremblay, Jean Christophe [Institute for Chemistry and Biochemistry, Freie Universität Berlin, Takustr. 3, D-14195 Berlin (Germany)

2016-05-14

In this contribution, we introduce a method for simulating dissipative, ultrafast many-electron dynamics in intense laser fields. The method is based on the norm-conserving stochastic unraveling of the dissipative Liouville-von Neumann equation in its Lindblad form. The N-electron wave functions sampling the density matrix are represented in the basis of singly excited configuration state functions. The interaction with an external laser field is treated variationally and the response of the electronic density is included to all orders in this basis. The coupling to an external environment is included via relaxation operators inducing transition between the configuration state functions. Single electron ionization is represented by irreversible transition operators from the ionizing states to an auxiliary continuum state. The method finds its efficiency in the representation of the operators in the interaction picture, where the resolution-of-identity is used to reduce the size of the Hamiltonian eigenstate basis. The zeroth-order eigenstates can be obtained either at the configuration interaction singles level or from a time-dependent density functional theory reference calculation. The latter offers an alternative to explicitly time-dependent density functional theory which has the advantage of remaining strictly valid for strong field excitations while improving the description of the correlation as compared to configuration interaction singles. The method is tested on a well-characterized toy system, the excitation of the low-lying charge transfer state in LiCN.

Physical equivalence of three forms of relativistic dynamics and addition of interactions in the front and instant forms

International Nuclear Information System (INIS)

Sokolov, S.N.

1977-01-01

The point, instant and front forms of the relativistic Hamiltonian theory are shown to be S-matrix equivalent in the general case (of many channels and particles with spin). The corresponding transformations are found. The problem of relativistic addition of the direct interactions is solved for the front and instant forms of dynamics

Relativistic heavy-atom effects on heavy-atom nuclear shieldings

Science.gov (United States)

Lantto, Perttu; Romero, Rodolfo H.; Gómez, Sergio S.; Aucar, Gustavo A.; Vaara, Juha

2006-11-01

The principal relativistic heavy-atom effects on the nuclear magnetic resonance (NMR) shielding tensor of the heavy atom itself (HAHA effects) are calculated using ab initio methods at the level of the Breit-Pauli Hamiltonian. This is the first systematic study of the main HAHA effects on nuclear shielding and chemical shift by perturbational relativistic approach. The dependence of the HAHA effects on the chemical environment of the heavy atom is investigated for the closed-shell X2+, X4+, XH2, and XH3- (X =Si-Pb) as well as X3+, XH3, and XF3 (X =P-Bi) systems. Fully relativistic Dirac-Hartree-Fock calculations are carried out for comparison. It is necessary in the Breit-Pauli approach to include the second-order magnetic-field-dependent spin-orbit (SO) shielding contribution as it is the larger SO term in XH3-, XH3, and XF3, and is equally large in XH2 as the conventional, third-order field-independent spin-orbit contribution. Considering the chemical shift, the third-order SO mechanism contributes two-thirds of the difference of ˜1500ppm between BiH3 and BiF3. The second-order SO mechanism and the numerically largest relativistic effect, which arises from the cross-term contribution of the Fermi contact hyperfine interaction and the relativistically modified spin-Zeeman interaction (FC/SZ-KE), are isotropic and practically independent of electron correlation effects as well as the chemical environment of the heavy atom. The third-order SO terms depend on these factors and contribute both to heavy-atom shielding anisotropy and NMR chemical shifts. While a qualitative picture of heavy-atom chemical shifts is already obtained at the nonrelativistic level of theory, reliable shifts may be expected after including the third-order SO contributions only, especially when calculations are carried out at correlated level. The FC/SZ-KE contribution to shielding is almost completely produced in the s orbitals of the heavy atom, with values diminishing with the principal

Relativistic Theory of Few Body Systems

Energy Technology Data Exchange (ETDEWEB)

Franz Gross

2002-11-01

Very significant advances have been made in the relativistic theory of few body systems since I visited Peter Sauer and his group in Hannover in 1983. This talk provides an opportunity to review the progress in this field since then. Different methods for the relativistic calculation of few nucleon systems are briefly described. As an example, seven relativistic calculations of the deuteron elastic structure functions, A, B, and T{sub 20}, are compared. The covariant SPECTATOR {copyright} theory, among the more successful and complete of these methods, is described in more detail.

Generation of Astron-Spherator configuration

International Nuclear Information System (INIS)

Narihara, Kazumichi; Hasegawa, Mitsuru; Tomita, Yukihiro; Tsuzuki, Tetsuya; Sato, Kuninori; Mohri, Akihiro.

1983-01-01

It was experimentally demonstrated that Astron-Spherator configuration is formed by injecting a pulsed relativistic electron beam in a toroidal device SPAC-VI with external toroidal and vertical magnetic fields. A plasma is confined in the extended magnetic region produced by a slender core of current carrying energetic electrons. This configuration continued for 40 ms without fatal instabilities. (author)

Superposition of configurations in semiempirical calculation of iron group ion spectra

International Nuclear Information System (INIS)

Kantseryavichyus, A.Yu.; Ramonas, A.A.

1976-01-01

The energy spectra of ions from the iron group in the dsup(N), dsup(N)s, dsup(N)p configurations are studied. A semiempirical method is used in which the effective hamiltonian contains configuration superposition. The sdsup(N+1), psup(4)dsup(N+2) quasidegenerated configurations, as well as configurations which differ by one electron are taken as correction configurations. It follows from the calculations that the most important role among the quasidegenerate configurations is played by the sdsup(N+1) correctional configuration. When it is taken into account, the introduction of the psup(4)dsup(N+2) correctional configuration practically does not affect the results. Account of the dsup(N-1)s configuration in the second order of the perturbation theory is equivalent to that of sdsup(N+1) in the sense that it results in the identical mean square deviation. As follows from the comparison of the results of the approximate and complete account of the configuration superposition, in many cases one can be satisfied with its approximate and complete account of the configuration superposition, in many cases one can be satisfied with its approximate version. The results are presented in the form of tables including the values of empirical parameters, radial integrals, mean square errors, etc

Scattering in relativistic particle mechanics

International Nuclear Information System (INIS)

De Bievre, S.

1986-01-01

The problem of direct interaction in relativistic particle mechanics has been extensively studied and a variety of models has been proposed avoiding the conclusions of the so-called no-interaction theorems. In this thesis the authors studied scattering in the relativistic two-body problem. He uses the results to analyze gauge invariance in Hamiltonian constraint models and the uniqueness of the symplectic structure in manifestly covariant relativistic particle mechanics. A general geometric framework that underlies approaches to relativistic particle mechanics is presented and the kinematic properties of the scattering transformation, i.e., those properties that arise solely from the invariance of the theory under the Poincare group are studied. The second part of the analysis of the relativistic two-body scattering problem is devoted to the dynamical properties of the scattering process. Using general geometric arguments, gauge invariance of the scattering transformation in the Todorov-Komar Hamiltonian constraint model is proved. Finally, quantization of the models is discussed

Self-interaction corrected local spin density calculations of actinides

DEFF Research Database (Denmark)

Petit, Leon; Svane, Axel; Szotek, Z

2010-01-01

We use the self-interaction corrected local spin-density approximation in order to describe localization-delocalization phenomena in the strongly correlated actinide materials. Based on total energy considerations, the methodology enables us to predict the ground-state valency configuration...... of the actinide ions in these compounds from first principles. Here we review a number of applications, ranging from electronic structure calculations of actinide metals, nitrides and carbides to the behaviour under pressure of intermetallics, and O vacancies in PuO2....

Benchmarks for electronically excited states: Time-dependent density functional theory and density functional theory based multireference configuration interaction

DEFF Research Database (Denmark)

Silva-Junior, Mario R.; Schreiber, Marko; Sauer, Stephan P. A.

2008-01-01

Time-dependent density functional theory (TD-DFT) and DFT-based multireference configuration interaction (DFT/MRCI) calculations are reported for a recently proposed benchmark set of 28 medium-sized organic molecules. Vertical excitation energies, oscillator strengths, and excited-state dipole...

Nanoscale multireference quantum chemistry: full configuration interaction on graphical processing units.

Science.gov (United States)

Fales, B Scott; Levine, Benjamin G

2015-10-13

Methods based on a full configuration interaction (FCI) expansion in an active space of orbitals are widely used for modeling chemical phenomena such as bond breaking, multiply excited states, and conical intersections in small-to-medium-sized molecules, but these phenomena occur in systems of all sizes. To scale such calculations up to the nanoscale, we have developed an implementation of FCI in which electron repulsion integral transformation and several of the more expensive steps in σ vector formation are performed on graphical processing unit (GPU) hardware. When applied to a 1.7 × 1.4 × 1.4 nm silicon nanoparticle (Si72H64) described with the polarized, all-electron 6-31G** basis set, our implementation can solve for the ground state of the 16-active-electron/16-active-orbital CASCI Hamiltonian (more than 100,000,000 configurations) in 39 min on a single NVidia K40 GPU.

Splitter target for controlling magnetic reconnection in relativistic laser plasma interactions

Science.gov (United States)

Gu, Y. J.; Bulanov, S. S.; Korn, G.; Bulanov, S. V.

2018-04-01

The utilization of a conical target irradiated by a high power laser is proposed to study fast magnetic reconnection in relativistic plasma interactions. Such target, placed in front of the near critical density gas jet, splits the laser pulse, forming two parallel laser pulses in the 2D case and a donut shaped pulse in the 3D case. The magnetic annihilation and reconnection occur in the density downramp region of the subsequent gas jet. The magnetic field energy is converted into the particle kinetic energy. As a result, a backward accelerated electron beam is obtained as a signature of reconnection. The above mechanisms are demonstrated using particle-in-cell simulations in both 2D and 3D cases. Facilitating the synchronization of two laser beams, the proposed approach can be used in designing the corresponding experiments on studying fundamental problems of relativistic plasma physics.

Degree of mapping for general relativistic kinks

International Nuclear Information System (INIS)

Harriot, Tina A.; Williams, J.G.

2005-01-01

The Finkelstein-Misner metrical kinks of general relativity are homo topically nontrivial light cone configurations that can occur on space-time hypersurfaces. The number of kinks corresponds to the winding number of a timelike vector field that that is determined from the metric. This paper uses the usual Euclidean integral formula for degree of mapping as a starting point and so produces a covariant formula that can be applied to counting general relativistic kinks in any dimension. The kink number is calculated for some simple-to-visualize examples in 2 + 1 dimensions. These include hypersurfaces of differing topologies and so have relevance to mechanisms of topology change in semi-classical theories of quantum gravity

Dynamical evolution of hadronic matter in relativistic collisions

International Nuclear Information System (INIS)

Dean, D.J.; Umar, A.S.; Strayer, M.R.

1993-01-01

We use the (3+1)-dimensional string-parton model to study relativistic collisions of heavy ions at CERN energies. Various inclusive hadronic observables, such as transverse energy, dE T /dη, and rapidity distributions, are calculated and compared with WA80 and NA35 data. We study secondary interactions that occur during the dynamical evolution, and show that these interactions tend to fill the midrapidity region. The dynamical evolution of the energy density of produced mesons and their thermodynamic properties are also studied

Relativistic duality, and relativistic and radiative corrections for heavy-quark systems

International Nuclear Information System (INIS)

Durand, B.; Durand, L.

1982-01-01

We give a JWKB proof of a relativistic duality relation which relates an appropriate energy average of the physical cross section for e + e - →qq-bar bound states→hadrons to the same energy average of the perturbative cross section for e + e - →qq-bar. We show that the duality relation can be used effectively to estimate relativistic and radiative corrections for bound-quark systems to order α/sub s//sup ts2/. We also present a formula which relates the square of the ''large'' 3 S 1 Salpeter-Bethe-Schwinger wave function for zero space-time separation of the quarks to the square of the nonrelativistic Schroedinger wave function at the origin for an effective potential which reproduces the relativistic spectrum. This formula allows one to use the nonrelativistic wave functions obtained in potential models fitted to the psi and UPSILON spectra to calculate relativistic leptonic widths for qq-bar states via a relativistic version of the van Royen--Weisskopf formula

Photoelectric effect in the relativistic domain revealed by the time-reversed process for highly charged uranium ions

International Nuclear Information System (INIS)

Stoehlker, T.; Mokler, P.H.; Kozhuharov, C.; Warczak, A.

1996-10-01

The photoelectric effect in the near relativistic energy regime of 80 to 350 keV is studied by the time-reversed process in ion-atom collisions, i.e. by the radiative capture of a quasi-free target electron. We review shell and subshell differential photon-angular distribution studies of radiative capture into highly-charged uranium ions. The experimental data are compared with exact relativistic calculations and give detailed insight into both the atomic structure of high-Z few-electron ions and into the fundamental electron-photon interaction process involved. In particular it is shown that the angular-differential measurements provide a unique method to study the magnetic interaction in relativistic electron-photon encoun- (orig.)

Lifetime for the Ti X spectrum

International Nuclear Information System (INIS)

Singh, Jagjit; Jha, A K S; Mohan, M

2010-01-01

We present configuration interaction calculations for the lifetime of 294 fine-structure levels of the Ti X spectrum in the LSJ coupling scheme. The calculations include all the major correlation effects. The relativistic effects are included by adding the mass correction term, Darwin term and spin-orbit interaction term to the non-relativistic Hamiltonian in the Breit-Pauli approximation. The calculated lifetime values are in very close agreement with other available experimental and theoretical results. We have predicted new lifetime results for levels belonging to 3p 2 3d, 3s 2 4p, 3s3p4s, 3s3p4p and various other configurations of Ti X, where no other theoretical and experimental results are available.

Relativistic and non-relativistic electronic molecular-structure calculations for dimers of 4p-, 5p-, and 6p-block elements.

Science.gov (United States)

Höfener, Sebastian; Ahlrichs, Reinhart; Knecht, Stefan; Visscher, Lucas

2012-12-07

We report results of non-relativistic and two-component relativistic single-reference coupled-cluster with single and double and perturbative triple excitations [CCSD(T)] treatments for the 4p-block dimers Ga(2) to Br(2) , the 5p-block dimers In(2) to I(2) , and their atoms. Extended basis sets up to pentuple zeta are employed and energies extrapolated to the complete basis-set limit. Relativistic and non-relativistic results for the dissociation energy D(e) are in close agreement with each other and previously published data, provided non-relativistic or scalar-relativistic results are corrected for spin-orbit contributions taken from the literature. An exception is Te(2) where theoretical results scatter by 0.085 eV. By virtue of this agreement it is unexpected that comparison with the experimental D(0) or D(e) dissociation energies (zero-point vibrational effects are negligible in this context) reveal errors larger than 0.1 eV for Ga(2), Ge(2), and Sb(2). Only relativistic treatments are presented for the 6p-block cases Tl(2) to At(2). Sufficient agreement with experimental data is found only for Pb(2) and Bi(2), the deviation of the computed and experimental D(0) values for Po(2) is again larger than 0.1 eV. Deviations of 0.1 eV between the computed and experimental D(0) values are a major reason for concern and call for additional investigations in both fields to clarify the situation. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Interaction of a relativistic charge with vacuum channel elements

International Nuclear Information System (INIS)

Tatarnikov, V.A.

1989-01-01

The problems of beam acceleration and transport require accounting for the effects connected with natural fields of charged particles. Flying along the accelerating structure elements the bunch induces charges and currents on the walls which, in their turn, affect the accelerating particles creating a secondary electromagnetic field. The effect of vacuum channel walls on the charged particle energy is considered. In the approximation of an assigned current the expressions for integral changes in the energy of relativistic charge, are obtained. The difference in the nature of charge interaction with the inhomogeneities of the diaphragm type and a semiinfinite waveguide, is shown

Structure and applications of point form relativistic quantum mechanics

International Nuclear Information System (INIS)

Klink, W.H.

2003-01-01

The framework of point form relativistic quantum mechanics is used to construct mass and current operators for hadronic systems with finite degree of freedom. For the point form all of the interactions are in the four-momentum operator and, since Lorentz transformations are kinematic, the theory is manifestly covariant. In the Bakamjian-Thomas version of the point form the four-momentum operator is written as a product of the four-velocity operator and mass operator, where the mass operator is the sum of free and interacting mass operators. Interacting mass operators can be constructed from vertices, matrix elements of local field operators evaluated at the space-time point zero, where the states are eigenstates of the four-velocity. Applications include the study of the spectra and widths of vector mesons, viewed as bound states of quark-antiquark pairs. Besides mass operators, current operators are needed to compute form factors. Form factors are matrix elements of current operators on mass operator eigenstates and are often calculated with one-body current operators (in the point form this is called the point form spectator approximation); but in a properly relativistic theory there must also be many-body current operators. Minimal currents needed to satisfy current conservation in the presence of hadronic interactions (called dynamically determined currents) are shown to be easily calculated in the point form. (author)

Intermolecular interactions

International Nuclear Information System (INIS)

Kaplan, I.G.; Rodimova, O.B.; AN SSSR, Tomsk. Inst. Optiki Atmosfery)

1978-01-01

The present state of the intermolecular interaction theory is described. The general physical picture of the molecular interactions is given, the relative contributions of interactions of different types are analyzed (electrostatic, resonance, induction, dispersion, relativistic, magnetostatic and exchange), and the main ones in each range of separations are picked out. The methods of the potential curve calculations are considered, specific for definite separations between the interacting systems. The special attention is paid to the analysis of approximations used in different theoretical calculation methods

MARTINI: An event generator for relativistic heavy-ion collisions

International Nuclear Information System (INIS)

Schenke, Bjoern; Gale, Charles; Jeon, Sangyong

2009-01-01

We introduce the modular algorithm for relativistic treatment of heavy ion interactions (MARTINI), a comprehensive event generator for the hard and penetrating probes in high-energy nucleus-nucleus collisions. Its main components are a time-evolution model for the soft background, PYTHIA 8.1, and the McGill-Arnold, Moore, and Yaffe (AMY) parton-evolution scheme, including radiative as well as elastic processes. This allows us to generate full event configurations in the high p T region that take into account thermal quantum chromodynamic (QCD) and quantum electrodynamic (QED) effects as well as effects of the evolving medium. We present results for the neutral pion nuclear modification factor in Au+Au collisions at the BNL Relativistic Heavy Ion Collider as a function of p T for different centralities and also as a function of the angle with respect to the reaction plane for noncentral collisions. Furthermore, we study the production of high-transverse-momentum photons, incorporating a complete set of photon-production channels.

Interaction potentials for multiquark states from instantons and other background gauge field configurations

International Nuclear Information System (INIS)

Warner, R.C.; Joshi, G.C.

1979-01-01

A simple rule is presented for calculating the contributions to the interaction potentials between constituent particles for a family of multiquark states, due to the presence of a semi-classical gauge field configuration which exists in a single SU(2) subgroup of colour SU(3). In multiquark states beyond the baryon many-body potential terms are found. The static (Wilson loop) limit is sufficient to elucidate the dependence of the potential on the colour structure of the multiquark state

Relativistic and Non-Relativistic Electronic Molecular-Structure Calculations for Dimers of 4p-, 5p-, and 6p-Block Elements

NARCIS (Netherlands)

Hoefener, S.; Ahlrichs, R.; Knecht, S.; Visscher, L.

2012-01-01

We report results of non-relativistic and two-component relativistic single-reference coupled-cluster with single and double and perturbative triple excitations [CCSD(T)] treatments for the 4p-block dimers Ga

A sparse matrix based full-configuration interaction algorithm

International Nuclear Information System (INIS)

Rolik, Zoltan; Szabados, Agnes; Surjan, Peter R.

2008-01-01

We present an algorithm related to the full-configuration interaction (FCI) method that makes complete use of the sparse nature of the coefficient vector representing the many-electron wave function in a determinantal basis. Main achievements of the presented sparse FCI (SFCI) algorithm are (i) development of an iteration procedure that avoids the storage of FCI size vectors; (ii) development of an efficient algorithm to evaluate the effect of the Hamiltonian when both the initial and the product vectors are sparse. As a result of point (i) large disk operations can be skipped which otherwise may be a bottleneck of the procedure. At point (ii) we progress by adopting the implementation of the linear transformation by Olsen et al. [J. Chem Phys. 89, 2185 (1988)] for the sparse case, getting the algorithm applicable to larger systems and faster at the same time. The error of a SFCI calculation depends only on the dropout thresholds for the sparse vectors, and can be tuned by controlling the amount of system memory passed to the procedure. The algorithm permits to perform FCI calculations on single node workstations for systems previously accessible only by supercomputers

Configurational forces in electronic structure calculations using Kohn-Sham density functional theory

Science.gov (United States)

Motamarri, Phani; Gavini, Vikram

2018-04-01

We derive the expressions for configurational forces in Kohn-Sham density functional theory, which correspond to the generalized variational force computed as the derivative of the Kohn-Sham energy functional with respect to the position of a material point x . These configurational forces that result from the inner variations of the Kohn-Sham energy functional provide a unified framework to compute atomic forces as well as stress tensor for geometry optimization. Importantly, owing to the variational nature of the formulation, these configurational forces inherently account for the Pulay corrections. The formulation presented in this work treats both pseudopotential and all-electron calculations in a single framework, and employs a local variational real-space formulation of Kohn-Sham density functional theory (DFT) expressed in terms of the nonorthogonal wave functions that is amenable to reduced-order scaling techniques. We demonstrate the accuracy and performance of the proposed configurational force approach on benchmark all-electron and pseudopotential calculations conducted using higher-order finite-element discretization. To this end, we examine the rates of convergence of the finite-element discretization in the computed forces and stresses for various materials systems, and, further, verify the accuracy from finite differencing the energy. Wherever applicable, we also compare the forces and stresses with those obtained from Kohn-Sham DFT calculations employing plane-wave basis (pseudopotential calculations) and Gaussian basis (all-electron calculations). Finally, we verify the accuracy of the forces on large materials systems involving a metallic aluminum nanocluster containing 666 atoms and an alkane chain containing 902 atoms, where the Kohn-Sham electronic ground state is computed using a reduced-order scaling subspace projection technique [P. Motamarri and V. Gavini, Phys. Rev. B 90, 115127 (2014), 10.1103/PhysRevB.90.115127].

On the binding energy of double Λ hypernuclei in the relativistic mean field theory

International Nuclear Information System (INIS)

Marcos, S.; Lombard, R.J.

1997-01-01

The binding energy of two Λ hyperons bound to a nuclear core is calculated within the relativistic mean field theory. The starting point is a two body relativistic equation of the Breit type suggested by the RMFT, and corrected for the two-particle interaction. The 2 Λ correlation energy is evaluated and the contribution of the δ and φ mesons, acting solely between hyperons, to the bond energy σB ΛΛ of ( ΛΛ ) 6 He, ( ΛΛ ) 10 Be and ( ΛΛ ) 13 B is calculated. Predictions of the ΔB ΛΛ A dependence are made for heavier Λ-hypernuclei. (K.A.)

Radiation dominated relativistic current sheets

International Nuclear Information System (INIS)

Jaroschek, C.H.

2008-01-01

Relativistic Current Sheets (RCS) feature plasma instabilities considered as potential key to magnetic energy dissipation and non-thermal particle generation in Poynting flux dominated plasma flows. We show in a series of kinetic plasma simulations that the physical nature of non-linear RCS evolution changes in the presence of incoherent radiation losses: In the ultra-relativistic regime (i.e. magnetization parameter sigma = 104 defined as the ratio of magnetic to plasma rest frame energy density) the combination of non-linear RCS dynamics and synchrotron emission introduces a temperature anisotropy triggering the growth of the Relativistic Tearing Mode (RTM). As direct consequence the RTM prevails over the Relativistic Drift Kink (RDK) Mode as competitive RCS instability. This is in contrast to the previously studied situation of weakly relativistic RCS (sigma ∼ 1) where the RDK is dominant and most of the plasma is thermalized. The simulations witness the typical life cycle of ultra-relativistic RCS evolving from a violent radiation induced collapse towards a radiation quiescent state in rather classical Sweet-Parker topology. Such a transition towards Sweet-Parker configuration in the late non-linear evolution has immediate consequences for the efficiency of magnetic energy dissipation and non-thermal particle generation. Ceasing dissipation rates directly affect our present understanding of non-linear RCS evolution in conventional striped wind scenarios. (author)

Calculation of 125Te NMR Chemical Shifts at the Full Four-Component Relativistic Level with Taking into Account Solvent and Vibrational Corrections: A Gateway to Better Agreement with Experiment.

Science.gov (United States)

Rusakova, Irina L; Rusakov, Yuriy Yu; Krivdin, Leonid B

2017-06-29

Four-component relativistic calculations of 125 Te NMR chemical shifts were performed in the series of 13 organotellurium compounds, potential precursors of the biologically active species, at the density functional theory level under the nonrelativistic and four-component fully relativistic conditions using locally dense basis set scheme derived from relativistic Dyall's basis sets. The relativistic effects in tellurium chemical shifts were found to be of as much as 20-25% of the total calculated values. The vibrational and solvent corrections to 125 Te NMR chemical shifts are about, accordingly, 6 and 8% of their total values. The PBE0 exchange-correlation functional turned out to give the best agreement of calculated tellurium shifts with their experimental values giving the mean absolute percentage error of 4% in the range of ∼1000 ppm, provided all corrections are taken into account.

Configuration interaction in charge exchange spectra of tin and xenon

Science.gov (United States)

D'Arcy, R.; Morris, O.; Ohashi, H.; Suda, S.; Tanuma, H.; Fujioka, S.; Nishimura, H.; Nishihara, K.; Suzuki, C.; Kato, T.; Koike, F.; O'Sullivan, G.

2011-06-01

Charge-state-specific extreme ultraviolet spectra from both tin ions and xenon ions have been recorded at Tokyo Metropolitan University. The electron cyclotron resonance source spectra were produced from charge exchange collisions between the ions and rare gas target atoms. To identify unknown spectral lines of tin and xenon, atomic structure calculations were performed for Sn14+-Sn17+ and Xe16+-Xe20+ using the Hartree-Fock configuration interaction code of Cowan (1981 The Theory of Atomic Structure and Spectra (Berkeley, CA: University of California Press)). The energies of the capture states involved in the single-electron process that occurs in these slow collisions were estimated using the classical over-barrier model.

All electron ab initio investigations of the electronic states of the FeC molecule

DEFF Research Database (Denmark)

Shim, Irene; Gingerich, Karl A.

1999-01-01

The low lying electronic states of the molecule FeC have been investigated by performing all electron ab initio multi-configuration self-consistent-field (CASSCF) and multi reference configuration interaction (MRCI) calculations. The relativistic corrections for the one electron Darwin contact term...

An Activity-Centric Approach to Configuration Work in Distributed Interaction

DEFF Research Database (Denmark)

Houben, Steven

The widespread introduction of new types of computing devices, such as smartphones, tablet computers, large interactive displays or even wearable devices, has led to setups in which users are interacting with a rich ecology of devices. These new device ecologies have the potential to introduce...... and captures the problems and challenges of distributed interaction. Using both empirical data and related work, I argue that configuration work is composed of: curation work, task resumption lag, mobility work, physical handling and articulation work. Using configuration work as a problem description, I...

Electromagnetic processes in relativistic heavy ion collisions

International Nuclear Information System (INIS)

Bertulani, C.A.; Universidade Federal do Rio de Janeiro; Baur, G.

1987-10-01

A study of the processes generated by the electromagnetic interaction in relativistic nuclear, and atomic collisions is presented. There is nowadays a vivid interest in this field due to the construction of relativistic heavy ion accelerators. Certainly, the most important purpose of these relativistic heavy ion machines is the study of nuclear matter under extreme conditions. In central nucleus-nucleus collisions one hopes to observe new forms of nuclear matter, like the quark-gluon plasma. On the other hand, very strong electromagnetic fields for a very short time are present in distant collisions with no nuclear contact. Such fields can also lead to interesting effects, which are discussed here. There has been many interesting theoretical and experimental developments on this subject, and new areas of research were opened. Of special interest is, e.g., the case of nuclear fragmentation. This is accomplished through the excitation of giant resonances or by direct breakt-up of the nuclei by means of their electromagnetic interaction. It is shown that this process can be used to study nuclear structure properties which are not accessible by means of the traditional electromagnetic excitation at nonrelativistic energies. The creation of particles is also of interest due the large cross sections, specially in the case of electron-positron pair creation. Although to explain the many processes originated in this way one can develop very elaborate and complicated calculations, the results can be understood in very simple terms because of our almost complete comprehension of the electromagntic interaction. For those processes where the electromagntic interaction plays the dominant role this is clearly a very useful tool for the investigation of the structures created by the strong interaction in the nuclei or hadrons. (orig.)

Second RPA calculations with the Skyrme and Gogny interactions

Energy Technology Data Exchange (ETDEWEB)

Gambacurta, Danilo [Horia Hulubei National Institute for Physics and Nuclear Engineering, Extreme Light Infrastructure - Nuclear Physics (ELI-NP), Magurele, Jud. Ilfov (Romania); Grasso, Marcella [Universite Paris-Sud, IN2P3-CNRS, Institut de Physique Nucleaire, Orsay Cedex (France)

2016-07-15

The Second Random Phase Approximation (SRPA) is a natural extension of RPA where more general excitation operators are introduced. These operators contain, in addition to the one particle-one hole configurations already considered in RPA, also two particle-two hole excitations. Only in the last years, large-scale SRPA calculations have been performed, showing the merits and limits of this approach. In the first part of this paper, we present an overview of recent applications of the SRPA based on the Skyrme and Gogny interactions. Giant resonances in {sup 16}O will be studied and their properties discussed by using different models. In particular, we will present the first applications of the SRPA model with the finite-range Gogny interaction, discussing the advantages and drawbacks of using such an interaction in this type of calculations. After that, some more recent results, obtained by using a subtraction procedure to overcome double-counting in the SRPA, will be discussed. We will show that this procedure leads to results that are weakly cutoff dependent and that a strong reduction of the SRPA downwards shift with respect to the RPA spectra is found. Moreover, applying this procedure for the first time in the Gogny-SRPA framework, we will show that this method is able to reduce the anomalous shift found in previous calculations and related to some proton-neutron matrix elements of the residual interaction. (orig.)

Relativistic Dirac-Fock and many-body perturbation calculations on He, He-like ions, Ne, and Ar

International Nuclear Information System (INIS)

Ishikawa, Y.

1990-01-01

Relativistic Dirac-Fock and diagrammatic many-body perturbation-theory calculations have been performed on He, several He-like ions, Ne, and Ar. The no-pair Dirac-Coulomb Hamiltonian is taken as the starting point. A solution of the Dirac-Fock equations is obtained by analytic expansion in basis sets of Gaussian-type functions. Many-body perturbation improvements of Coulomb correlation are done to third order

Amino acids interacting with defected carbon nanotubes: ab initio calculations

Directory of Open Access Journals (Sweden)

M. Darvish Ganji

2016-09-01

Full Text Available The adsorption of a number of amino acids on a defected single-walled carbon nanotube (SWCNT is investigated by using the density-functional theory (DFT calculations. The adsorption energies and equilibrium distances are calculated for various configurations such as amino acid attaching to defect sites heptagon, pentagon and hexagon in defective tube and also for several molecular orientations with respect to the nanotube surface. The results showed that amino acids prefer to be physisorbed on the outer surface of the defected nanotube with different interaction strength following the hierarchy histidine > glycine > phenylalanine > cysteine. Comparing these findings with those obtained for perfect SWCNTs reveals that the adsorption energy of the amino acids increase for adsorption onto defected CNTs. The adsorption nature has also been evaluated by means of electronics structures analysis within the Mulliken population and DOS spectra for the interacting entities.

A fully relativistic approach for calculating atomic data for highly charged ions

Energy Technology Data Exchange (ETDEWEB)

Zhang, Hong Lin [Los Alamos National Laboratory; Fontes, Christopher J [Los Alamos National Laboratory; Sampson, Douglas H [PENNSYLVANIA STATE UNIV

2009-01-01

We present a review of our fully relativistic approach to calculating atomic data for highly charged ions, highlighting a research effort that spans twenty years. Detailed discussions of both theoretical and numerical techniques are provided. Our basic approach is expected to provide accurate results for ions that range from approximately half ionized to fully stripped. Options for improving the accuracy and range of validity of this approach are also discussed. In developing numerical methods for calculating data within this framework, considerable emphasis is placed on techniques that are robust and efficient. A variety of fundamental processes are considered including: photoexcitation, electron-impact excitation, electron-impact ionization, autoionization, electron capture, photoionization and photorecombination. Resonance contributions to a variety of these processes are also considered, including discussions of autoionization, electron capture and dielectronic recombination. Ample numerical examples are provided in order to illustrate the approach and to demonstrate its usefulness in providing data for large-scale plasma modeling.

Analytic approach to the relativistic problem of constructing effective nucleon-nucleon and pion-nucleon interaction operators at low and intermediate energies

International Nuclear Information System (INIS)

Safronov, A.N.; Safronov, A.A.

2006-01-01

Full text: A nonperturbative character of QCD at low and intermediate energies generates serious mathematical difficulties in describing the dynamics of hadron-hadron interactions in terms quark-gluon degrees of freedom. Therefore much effort has gone in past years into developing QCD-motivated approaches that formulate the theory of strong interaction in terms of hadron degrees of freedom. The path-integral technique together with idea of spontaneous chiral-symmetry breaking leads to Effective Field Theory (EFT) [1]. Unfortunately EFT can be applied to description of hadron-hadron interactions only at very low energies. On the other hand, meson theories of nuclear forces have long since been used to describe the properties of nucleon systems and scattering processes. Now it is not quite clear, up to what distances the meson-exchange pattern of nuclear forces is valid. Recently the new relativistic approach to the problem of constructing effective hadron-hadron interaction operators has been proposed [2-4] on the basis of analytic S-matrix theory and Gelfand-Levitan-Marchenko-Martin methods for solving the inverse quantum scattering problem. In this approach effective potential is defined as a local operator in a partial-wave equation of the quasipotential type such that it generates on-shell relativistic (Feynman) scattering amplitude that has required discontinuities at dynamical cuts. The discontinuities of partial-wave amplitudes are determined by model-independent quantities (renormalized vertex constants and amplitudes of subprocesses involving on-mass-shell particles off the physical region) and can be calculated by methods of relativistic quantum field theory within various dynamical approaches. In particular, EFT can be used to calculate the discontinuities across dynamical-cut segments closest to the physical region. In [2-4] we have examined the basic features of the proposed approach. Attention has been given primarily to analyzing the new mechanism of

Problems of describing the cumulative effect in relativistic nuclear physics

International Nuclear Information System (INIS)

Baldin, A.M.

1979-01-01

The problem of describing the cumulative effect i.e., the particle production on nuclei in the range kinematically forbidden for one-nucleon collisions, is studied. Discrimination of events containing cumulative particles fixes configurations in the wave function of a nucleus, when several nucleons are closely spaced and their quark-parton components are collectivized. For the cumulative processes under consideration large distances between quarks are very important. The fundamental facts and theoretical interpretation of the quantum field theory and of the condensed media theory in the relativistic nuclear physics are presented in brief. The collisions of the relativistic nuclei with low momentum transfers is considered in a fast moving coordinate system. The basic parameter determining this type of collisions is the energy of nucleon binding in nuclei. It has been shown that the short-range correlation model provides a good presentation of many characteristics of the multiple particle production and it may be regarded as an approximate universal property of hadron interactions

An Interaction Measure for Control Configuration Selection for Multivariable Bilinear Systems

DEFF Research Database (Denmark)

Shaker, Hamid Reza; Stoustrup, Jakob

2013-01-01

are needed to be controlled, are nonlinear and linear models are insufficient to describe the behavior of the processes. The focus of this paper is on the problem of control configuration selection for a class of nonlinear systems which is known as bilinear systems. A gramian-based interaction measure...... for control configuration selection of MIMO bilinear processes is described. In general, most of the results on the control configuration selection, which have been proposed so far, can only support linear systems. The proposed gramian-based interaction measure not only supports bilinear processes but also...

Conjugate calculation of a film-cooled blade for improvement of the leading edge cooling configuration

Directory of Open Access Journals (Sweden)

Norbert Moritz

2013-03-01

Full Text Available Great efforts are still put into the design process of advanced film-cooling configurations. In particular, the vanes and blades of turbine front stages have to be cooled extensively for a safe operation. The conjugate calculation technique is used for the three-dimensional thermal load prediction of a film-cooled test blade of a modern gas turbine. Thus, it becomes possible to take into account the interaction of internal flows, external flow, and heat transfer without the prescription of heat transfer coefficients. The focus of the investigation is laid on the leading edge part of the blade. The numerical model consists of all internal flow passages and cooling hole rows at the leading edge. Furthermore, the radial gap flow is also part of the model. The comparison with thermal pyrometer measurements shows that with respect to regions with high thermal load a qualitatively and quantitatively good agreement of the conjugate results and the measurements can be found. In particular, the region in the vicinity of the mid-span section is exposed to a higher thermal load, which requires further improvement of the cooling arrangement. Altogether the achieved results demonstrate that the conjugate calculation technique is applicable for reasonable prediction of three-dimensional thermal load of complex cooling configurations for blades.

The levels of the first excited configuration of one-electron ions in intensive alternating field

International Nuclear Information System (INIS)

Klimchitskaya, G.L.

1984-01-01

The relativistic generalization of the quasi-energy method is applied for the calculation of the influence of spatjally-homogeneous electric field with the periodic time dependence on the energy levels of the first excited configuration of one-electron multiply charged ions. The dependence is found of the corresponding quasi-energy levels on the amplitude and frequency of intensive external field which wholly mixes the levels of fine structure

Thermodynamic equilibrium in relativistic rotating systems

International Nuclear Information System (INIS)

Suen, W.M.; Washington Univ., St. Louis, MO; Young, K.

1988-01-01

The thermodynamic equilibrium configurations of relativistic rotating stars are studied using the maximum entropy principle. It is shown that the heuristic arguments for the equilibrium conditions can be developed into a maximum entropy principle in which the variations are carried out in a fixed background spacetime. This maximum principle with the fixed background assumption is technically simpler than, but has to be justified by, a maximum entropy principle without the assumption. Such a maximum entropy principle is formulated in this paper, showing that the general relativistic system can be treated on the same footing as other long-range force systems. (author)

Coherent emission from relativistic beam-plasma interactions

International Nuclear Information System (INIS)

Latham, P.E.

1986-01-01

A theoretical model for the production of high-power, high-frequency electromagnetic radiation from unmagnetized, relativistic beam-plasma interactions is studied. Emphasis is placed on the injected-beam system, for which the dominant portion of the radiation is emitted near the point where the beam enters the plasma. In such systems, frequencies much larger than the plasma frequency and power levels many orders of magnitude above that predicted by single-particle radiation have been observed experimentally. A two-step process is proposed to explain these observations: electrostatic bunching of the beam followed by coherent radiation by the bunches. The first step, beam bunching, produces large-amplitude electrostatic waves. A Green's function analysis is employed to understand the convective growth of those waves near the plasma boundary; their saturation amplitude is found by applying conservation of energy to the beam-plasma system. An azimuthally symmetric model is used to compute the saturated spectrum analytically, and a relatively simple expression is found. The second step, the interaction of the electron beam with the electrostatic spectrum, leads to the production of high-power, high-frequency electromagnetic radiation. From a detailed analysis of the phase-space evolution of the trapped beam, an analytic expression for the electromagnetic spectrum is found as a function of angle and frequency

Spin currents, relativistic effects and the Darwin interaction in the theory of hole superconductivity

International Nuclear Information System (INIS)

Hirsch, J.E.

2005-01-01

The existence of macroscopic spin currents in the ground state of superconductors is predicted within the theory of hole superconductivity. Here it is shown that the electromagnetic Darwin interaction is attractive for spin currents and repulsive for charge currents. It is also shown that the mere existence of spin currents implies that some electrons are moving at relativistic speeds in macroscopic superconductors, which in turn implies that the Darwin interaction plays a fundamental role in stabilizing the superconducting state

Local density approximations for relativistic exchange energies

International Nuclear Information System (INIS)

MacDonald, A.H.

1986-01-01

The use of local density approximations to approximate exchange interactions in relativistic electron systems is reviewed. Particular attention is paid to the physical content of these exchange energies by discussing results for the uniform relativistic electron gas from a new point of view. Work on applying these local density approximations in atoms and solids is reviewed and it is concluded that good accuracy is usually possible provided self-interaction corrections are applied. The local density approximations necessary for spin-polarized relativistic systems are discussed and some new results are presented

Multireference configuration interaction study on spectroscopic properties of low-lying electronic states of As2 molecule

International Nuclear Information System (INIS)

Wang Jie-Min; Liu Qiang

2013-01-01

The potential energy curves (PECs) of four electronic states (X 1 Σ g + , e 3 Δ u , a 3 Σ u − , and d 3 Π g ) of an As 2 molecule are investigated employing the complete active space self-consistent field (CASSCF) method followed by the valence internally contracted multireference configuration interaction (MRCI) approach in conjunction with the correlation-consistent aug-cc-pV5Z basis set. The effect on PECs by the relativistic correction is taken into account. The way to consider the relativistic correction is to employ the second-order Douglas-Kroll Hamiltonian approximation. The correction is made at the level of a cc-pV5Z basis set. The PECs of the electronic states involved are extrapolated to the complete basis set limit. With the PECs, the spectroscopic parameters (T e , R e , ω e , ω e x e , ω e y e , α e , β e , γ e , and B e ) of these electronic states are determined and compared in detail with those reported in the literature. Excellent agreement is found between the present results and the experimental data. The first 40 vibrational states are studied for each electronic state when the rotational quantum number J equals zero. In addition, the vibrational levels, inertial rotation and centrifugal distortion constants of d 3 Π g electronic state are reported which are in excellent agreement with the available measurements. Comparison with the experimental data shows that the present results are both reliable and accurate. (atomic and molecular physics)

Calculation of Rydberg interaction potentials

International Nuclear Information System (INIS)

Weber, Sebastian; Büchler, Hans Peter; Tresp, Christoph; Urvoy, Alban; Hofferberth, Sebastian; Menke, Henri; Firstenberg, Ofer

2017-01-01

The strong interaction between individual Rydberg atoms provides a powerful tool exploited in an ever-growing range of applications in quantum information science, quantum simulation and ultracold chemistry. One hallmark of the Rydberg interaction is that both its strength and angular dependence can be fine-tuned with great flexibility by choosing appropriate Rydberg states and applying external electric and magnetic fields. More and more experiments are probing this interaction at short atomic distances or with such high precision that perturbative calculations as well as restrictions to the leading dipole–dipole interaction term are no longer sufficient. In this tutorial, we review all relevant aspects of the full calculation of Rydberg interaction potentials. We discuss the derivation of the interaction Hamiltonian from the electrostatic multipole expansion, numerical and analytical methods for calculating the required electric multipole moments and the inclusion of electromagnetic fields with arbitrary direction. We focus specifically on symmetry arguments and selection rules, which greatly reduce the size of the Hamiltonian matrix, enabling the direct diagonalization of the Hamiltonian up to higher multipole orders on a desktop computer. Finally, we present example calculations showing the relevance of the full interaction calculation to current experiments. Our software for calculating Rydberg potentials including all features discussed in this tutorial is available as open source. (tutorial)

Whispering gallery effect in relativistic optics

Science.gov (United States)

Abe, Y.; Law, K. F. F.; Korneev, Ph.; Fujioka, S.; Kojima, S.; Lee, S.-H.; Sakata, S.; Matsuo, K.; Oshima, A.; Morace, A.; Arikawa, Y.; Yogo, A.; Nakai, M.; Norimatsu, T.; d'Humières, E.; Santos, J. J.; Kondo, K.; Sunahara, A.; Gus'kov, S.; Tikhonchuk, V.

2018-03-01

relativistic laser pulse, confined in a cylindrical-like target, under specific conditions may perform multiple scattering along the internal target surface. This results in the confinement of the laser light, leading to a very efficient interaction. The demonstrated propagation of the laser pulse along the curved surface is just yet another example of the "whispering gallery" effect, although nonideal due to laser-plasma coupling. In the relativistic domain its important feature is a gradual intensity decrease, leading to changes in the interaction conditions. The proccess may pronounce itself in plenty of physical phenomena, including very efficient electron acceleration and generation of relativistic magnetized plasma structures.

Relativistic total and differential cross section proton--proton electron--positron pair production calculation

International Nuclear Information System (INIS)

Rubinstein, J.E.

1976-01-01

Circle Feynman diagrams for a specific permutation of variables along with their corresponding algebraic expressions are presented to evaluate [H] 2 for proton-proton electron-positron pair production. A Monte Carlo integration technique is introduced and is used to set up the multiple integral expression for the total pair production cross section. The technique is first applied to the Compton scattering problem and then to an arbitrary multiple integral. The relativistic total cross section for proton-proton electron-positron pair production was calculated for eight different values of incident proton energy. A variety of differential cross sections were calculated for the above energies. Angular differential cross section distributions are presented for the electron, positron, and proton. Invariant mass differential cross section distributions are done both with and without the presence of [H] 2 . Both WGHT and log 10 (TOTAL) distributions were also obtained. The general behavioral trends of the total and differential cross sections for proton-proton electron-positron pair production are presented. The range of validity for this calculation is from 0 to about 200 MeV

Calculation of levels, transition rates, and lifetimes for the arsenic isoelectronic sequence Sn XVIII-Ba XXIV, W XLII

Science.gov (United States)

Wang, K.; Chen, Z. B.; Chen, C. Y.; Yan, J.; Dang, W.; Zhao, X. H.; Yang, X.

2017-09-01

Multi-configuration Dirac-Fock (MCDF) calculations of energy levels, wavelengths, oscillator strengths, lifetimes, and electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2), magnetic quadrupole (M2) transition rates are reported for the arsenic isoelectronic sequence Sn XVIII-Ba XXIV, W XLII. Results are presented among the 86 levels of the 4s2 4p3, 4 s 4p4, 4p5, 4s2 4p2 4 d, and 4 s 4p3 4 d configurations in each ion. The relativistic atomic structure package GRASP2K is adopted for the calculations, in which the contributions from the correlations within the n ≤ 7 complexes, Breit interaction (BI) and quantum electrodynamics (QED) effects are taking into account. The many-body perturbation theory (MBPT) method is also employed as an independent calculation for comparison purposes, taking W XLII as an example. Calculated results are compared with data from other calculations and the observed values from the Atomic Spectra Database (ASD) of the National Institute of Standards and Technology (NIST). Good agreements are obtained. i.e, the accuracy of our energy levels is assessed to be better than 0.6%. These accurate theoretical data should be useful for diagnostics of hot plasmas in fusion devices.

An investigation of relativistic microscopic optical potential in terms of relativistic Brueckner-Bethe-Goldstone equation

International Nuclear Information System (INIS)

Chen Baoqiu; Ma Zhongyu

1992-01-01

Relativistic microscopic optical potential of nucleon-nucleus is derived from the relativistic Brueckner-Bethe-Goldstone (RBBG) equation. The complex effective mass of a nucleon is determined by a fit to 200 MeV p- 40 Ca scattering data. The relativistic microscopic optical potentials with this effective mass are obtained from RBBG for p- 16O , 40 Ca, 90 Zr and 208 Pb scattering in energy range from 160 to 800 MeV. The microscopic optical potential is used to study the proton- 40 Ca scattering problem at 200 MeV. The results, such as differential cross section, analyzing power and spin rotation function are compared with those calculated from phenomenological relativistic optical potential

Breakup of relativistic π+π- atoms in matter

International Nuclear Information System (INIS)

Afanasyev, L.G.; Tarasov, A.V.

1996-01-01

The relativistic motion of atoms formed by π+ and π- mesons in matter is considered. Exact analytic expressions for the form factors of hydrogenlike atoms for discrete-discrete transitions are obtained in a form convenient for numerical calculations. The total and transition cross sections for the interaction of π+π- atoms with matter are calculated in the Born approximation. The evolution of atomic-state populations is treated in terms of kinetic equations. The method of calculation makes it possible to obtain the populations of discrete atomic states, as well as the probability of transitions to the continuous spectrum (ionization). The proposed method yields the first experimental estimate of the lifetime of the π+π- atom

Relativistic and Non-Relativistic Electronic Molecular-Structure Calculations for Dimers of 4p-, 5p-, and 6p-Block Elements

DEFF Research Database (Denmark)

Hofener, S.; Ahlrichs, R.; Knecht, S.

2012-01-01

We report results of non-relativistic and two-component relativistic single-reference coupled-cluster with single and double and perturbative triple excitations [CCSD(T)] treatments for the 4p-block dimers Ga2 to Br2, the 5p-block dimers In2 to I2, and their atoms. Extended basis sets up...

Relativistic effects in ab initio electron-nucleus scattering

Science.gov (United States)

Rocco, Noemi; Leidemann, Winfried; Lovato, Alessandro; Orlandini, Giuseppina

2018-05-01

The electromagnetic responses obtained from Green's function Monte Carlo (GFMC) calculations are based on realistic treatments of nuclear interactions and currents. The main limitations of this method comes from its nonrelativistic nature and its computational cost, the latter hampering the direct evaluation of the inclusive cross sections as measured by experiments. We extend the applicability of GFMC in the quasielastic region to intermediate momentum transfers by performing the calculations in a reference frame that minimizes nucleon momenta. Additional relativistic effects in the kinematics are accounted for employing the two-fragment model. In addition, we developed a novel algorithm, based on the concept of first-kind scaling, to compute the inclusive electromagnetic cross section of 4He through an accurate and reliable interpolation of the response functions. A very good agreement is obtained between theoretical and experimental cross sections for a variety of kinematical setups. This offers a promising prospect for the data analysis of neutrino-oscillation experiments that requires an accurate description of nuclear dynamics in which relativistic effects are fully accounted for.

Cross sections for electron-impact excitation of krypton from the levels of 4p6, 4p55s, and 4p55p configurations

International Nuclear Information System (INIS)

Zeng Jiaolong; Yuan Jianmin; Wu Jianhua; Jin Fengtao; Zhao Gang

2005-01-01

The electron-impact excitation cross sections at low electron energies have been calculated using a fully relativistic R-matrix method for transitions between levels of 4p 6 , 4p 5 5s, and 4p 5 5p configurations. To ensure the convergence of results, we have paid special attention to the factors that may affect the convergence of cross sections. For examples, we have included extensive configuration interactions in the wave-function expansion of the target states. A large enough R-matrix boundary has been taken to ensure the convergence of atomic wave functions. Contributions to cross sections from a large number of partial waves (up to J=39.5) have been explicitly calculated. The final results are in good agreement with recent experimental data by Jung et al. [Phys. Rev. Lett. 94, 163202 (2005)] after shifting the position of electron energy. The relative difference is about 10% for four transitions out of the metastable levels. The results eliminated the significant discrepancies between theory and experimental work on excitation cross sections out of the metastable levels reported in the literature

Four-component relativistic density functional theory calculations of NMR shielding tensors for paramagnetic systems.

Science.gov (United States)

Komorovsky, Stanislav; Repisky, Michal; Ruud, Kenneth; Malkina, Olga L; Malkin, Vladimir G

2013-12-27

A four-component relativistic method for the calculation of NMR shielding constants of paramagnetic doublet systems has been developed and implemented in the ReSpect program package. The method uses a Kramer unrestricted noncollinear formulation of density functional theory (DFT), providing the best DFT framework for property calculations of open-shell species. The evaluation of paramagnetic nuclear magnetic resonance (pNMR) tensors reduces to the calculation of electronic g tensors, hyperfine coupling tensors, and NMR shielding tensors. For all properties, modern four-component formulations were adopted. The use of both restricted kinetically and magnetically balanced basis sets along with gauge-including atomic orbitals ensures rapid basis-set convergence. These approaches are exact in the framework of the Dirac-Coulomb Hamiltonian, thus providing useful reference data for more approximate methods. Benchmark calculations on Ru(III) complexes demonstrate good performance of the method in reproducing experimental data and also its applicability to chemically relevant medium-sized systems. Decomposition of the temperature-dependent part of the pNMR tensor into the traditional contact and pseudocontact terms is proposed.

Relativistic quantum mechanic calculation of photoionization cross-section of hydrogenic and non-hydrogenic states using analytical potentials

International Nuclear Information System (INIS)

Rodriguez, R.; Gil, J.M.; Rubiano, J.G.; Florido, R.; Martel, P.; Minguez, E.

2005-01-01

Photoionization process is a subject of special importance in many areas of physics. Numerical methods must be used in order to obtain photoionization cross-sections for non-hydrogenic levels. The atomic data required to calculate them is huge so self-consistent calculations increase computing time considerably. Analytical potentials are a useful alternative because they avoid the iterative procedures typical in self-consistent models. In this work, we present a relativistic quantum calculation of photoionization cross-sections for isolated ions based on an analytical potential to obtain the required atomic data, which is valid both for hydrogenic and non-hydrogenic ions. Comparisons between our results and others obtained using either widely used analytical expressions for the cross-sections or more sophisticated calculations are done

Local unitary transformation method for large-scale two-component relativistic calculations: case for a one-electron Dirac Hamiltonian.

Science.gov (United States)

Seino, Junji; Nakai, Hiromi

2012-06-28

An accurate and efficient scheme for two-component relativistic calculations at the spin-free infinite-order Douglas-Kroll-Hess (IODKH) level is presented. The present scheme, termed local unitary transformation (LUT), is based on the locality of the relativistic effect. Numerical assessments of the LUT scheme were performed in diatomic molecules such as HX and X(2) (X = F, Cl, Br, I, and At) and hydrogen halide clusters, (HX)(n) (X = F, Cl, Br, and I). Total energies obtained by the LUT method agree well with conventional IODKH results. The computational costs of the LUT method are drastically lower than those of conventional methods since in the former there is linear-scaling with respect to the system size and a small prefactor.

Effective potentials of the relativistic three-body problem with electromagnetic interaction in adiabatic approximation

International Nuclear Information System (INIS)

Bakalov, D.D.; Melezhik, V.S.

1987-01-01

The relativistic Hamiltonian for 3-spin particles with electromagnetic interaction has been represented in the form of a sum of terms with factorized dependence on spin, angular and spheroidal variable, and its matrix elements have been expressed in terms of the matrix elements of a small number of ''basic'' operators. The numerical values of the latter have been tabulated, thus allowing for the evaluation of the leading relativistic effects in any 3-body system (with unit particle charge) with and accuracy of ∼ 0(1/2M), where 1/2M=(M 1 -1 +M 2 -1 )/2(M 1 -1 +M 3 -1 ) is the small parameter of the adiabatic expansion (M i , i=1,2,3 being particle masses)

Relativistic scattering theory of two charged spinless particles

International Nuclear Information System (INIS)

Alt, E.O.; Hannemann

1985-01-01

In the framework of a relativistic quantum mechanics, the authors calculate for two spinless particles with Coulomb interaction exactly the partial-wave S-matrix and the full scattering amplitude. From the former they can extract the exact binding energies which, when expanded in powers of α, reproduce in the hydrogenic case the fourth-order result of a previous study. In the weak field limit, the latter coincides with the amplitude derived by another study from QED in eikonal approximation

Solved and unsolved problems in relativistic quantum chemistry

International Nuclear Information System (INIS)

Kutzelnigg, Werner

2012-01-01

Graphical abstract: The graphical abstract represents the Dirac-Coulomb Hamiltonian in Fock space in a diagrammatic notation. A line (vertical or slanted) with an upgoing arrow represents an eletron, with a downgoing arrow a positron. A cross in the first line means the potential created by a nucleus, a broken line represents the Coulomb interaction between electrons and positrons. Highlights: ► Relativistic many-electron theory needs a Fock space and a field-dependent vacuum. ► A good starting point is QED in Coulomb gauge without transversal photons. ► The Dirac underworld picture is obsolete. ► A kinetically balanced even-tempered Gaussian basis is complete. ► ‘Quantum chemistry in Fock space is preferable over QED. - Abstract: A hierarchy of approximations in relativistic many-electron theory is discussed that starts with the Dirac equation and its expansion in a kinetically balanced basis, via a formulation of non-interacting electrons in Fock space (which is the only consistent way to deal with negative-energy states). The most straightforward approximate Hamiltonian for interacting electrons is derived from quantum electrodynamics (QED) in Coulomb gauge with the neglect of transversal photons. This allows an exact (non-perturbative) decoupling of the electromagnetic field from the fermionic field. The electric interaction of the fermions is non-retarded and non-quantized. The quantization of the fermionic field leads to a polarizable vacuum. The simplest (but somewhat problematic) approximation is a no-pair projected theory with external-field projectors. The Dirac-Coulomb operator in configuration space (first quantization) is not acceptable, even if the Brown–Ravenhall disease is much less virulent than often claimed. Effects of transversal photons, such as the Breit interaction and renormalized self-interaction can be taken care of perturbatively at the end, but there are still many open questions.

Rayleigh-Brillouin spectrum in special relativistic hydrodynamics

International Nuclear Information System (INIS)

Garcia-Perciante, A. L.; Garcia-Colin, L. S.; Sandoval-Villalbazo, A.

2009-01-01

In this paper we calculate the Rayleigh-Brillouin spectrum for a relativistic simple fluid according to three different versions available for a relativistic approach to nonequilibrium thermodynamics. An outcome of these calculations is that Eckart's version predicts that such spectrum does not exist. This provides an argument to question its validity. The remaining two results, which differ one from another, do provide a finite form for such spectrum. This raises the rather intriguing question as to which of the two theories is a better candidate to be taken as a possible version of relativistic nonequilibrium thermodynamics. The answer will clearly require deeper examination of this problem.

Re-appraisal of the P, T-odd interaction constant Wd in YbF ...

Indian Academy of Sciences (India)

... Lecture Workshops · Refresher Courses · Symposia · Live Streaming. Home; Journals; Pramana – Journal of Physics; Volume 73; Issue 3. Re-appraisal of the , -odd interaction constant d in YbF: Relativistic configuration interaction approach. Malaya K Nayak Rajat K Chaudhuri. Volume 73 Issue 3 September 2009 ...

A new formulation of the relativistic many-body theory of electric dipole moments of closed shell atoms

International Nuclear Information System (INIS)

Latha, K V P; Angom, Dilip; Chaudhuri, Rajat K; Das, B P; Mukherjee, Debashis

2007-01-01

The electric dipole moments of closed-shell atoms are sensitive to the parity and time-reversal violating phenomena in the nucleus. The nuclear Schiff moment is one such property, it arises from the parity and time reversal violating quark-quark interactions and the quark-chromo electric dipole moments. We calculate the electric dipole moment of atomic 199 Hg arising from the nuclear Schiff moment using the relativistic coupled-cluster theory. This is the most accurate calculation of the quantity to date. Our calculations in combination with the experiment data provide important insights to the P and T violating coupling constants at the elementary particle level. In addition, a new limit on the tensor-pseudo tensor induced atomic EDM, calculated using the relativistic coupled-cluster theory is also presented

Positron-attachment to small molecules: Vibrational enhancement of positron affinities with configuration interaction level of multi-component molecular orbital approach

Energy Technology Data Exchange (ETDEWEB)

Tachikawa, Masanori [Quantum Chemistry Division, Graduate School of NanoBioScience, Yokohama City University, 22-2 Seto, Kanazawa, Yokohama 236-0027 (Japan)

2015-12-31

To theoretically demonstrate the binding of a positron to small polarized molecules, we have calculated the vibrational averaged positron affinity (PA) values along the local vibrational contribution with the configuration interaction level of multi-component molecular orbital method. This method can take the electron-positron correlation contribution into account through single electronic - single positronic excitation configurations. The PA values are enhanced by including the local vibrational contribution from vertical PA values due to the anharmonicity of the potential.

Analysis of core plasma heating and ignition by relativistic electrons

International Nuclear Information System (INIS)

Nakao, Y.

2002-01-01

Clarification of the pre-compressed plasma heating by fast electrons produced by relativistic laser-plasma interaction is one of the most important issues of the fast ignition scheme in ICF. On the basis of overall calculations including the heating process, both by relativistic hot electrons and alpha-particles, and the hydrodynamic evolution of bulk plasma, we examine the feature of core plasma heating and the possibility of ignition. The deposition of the electron energy via long-range collective mode, i.e. Langmuir wave excitation, is shown to be comparable to that through binary electron-electron collisions; the calculation neglecting the wave excitation considerably underestimates the core plasma heating. The ignition condition is also shown in terms of the intensity I(h) and temperature T(h) of hot electrons. It is found that I(h) required for ignition increases in proportion to T(h). For efficiently achieving the fast ignition, electron beams with relatively 'low' energy (e.g.T(h) below 1 MeV) are desirable. (author)

Coulomb effects in relativistic laser-assisted Mott scattering

International Nuclear Information System (INIS)

Ngoko Djiokap, J.M.; Kwato Njock, M.G.; Tetchou Nganso, H.M.

2004-09-01

We reconsider the influence of the Coulomb interaction on the process of relativistic Mott scattering in a powerful electromagnetic plane wave for which the ponderomotive energy is of the order of the magnitude of the electron's rest mass. Coulomb effects of the bare nucleus on the laser-dressed electron are treated more completely than in the previous work of Li et al. [J. Phys. B: At. Mol. Opt. Phys. 37 (2004) 653]. To this end we use Coulomb-Dirac-Volkov functions to describe the initial and the final states of the electron. First-order Born differential cross sections of induced and inverse bremsstrahlung are obtained for circularly and linearly polarized laser light. Numerical calculations are carried out from both polarizations, for various nucleus charge values, three angular configurations and an incident energy in the MeV range. It is found that for parameters used in the present work, incorporating Coulomb effects of the target nucleus either in the initial state or in the final state yields cross sections which are quite similar whatever the scattering geometry and polarization considered. When Coulomb distortions are included in both states, the cross sections are strongly modified with the increase of Z, as compared to the outcome of the prior form of the T-matrix treatment. (author)

A combined DFT and restricted open-shell configuration interaction method including spin-orbit coupling: Application to transition metal L-edge X-ray absorption spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Roemelt, Michael; Maganas, Dimitrios; Neese, Frank [Max-Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, D-45470 Muelheim an der Ruhr (Germany); DeBeer, Serena [Max-Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, D-45470 Muelheim an der Ruhr (Germany); Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853 (United States)

2013-05-28

A novel restricted-open-shell configuration interaction with singles (ROCIS) approach for the calculation of transition metal L-edge X-ray absorption spectra is introduced. In this method, one first calculates the ground state and a number of excited states of the non-relativistic Hamiltonian. By construction, the total spin is a good quantum number in each of these states. For a ground state with total spin S excited states with spin S Prime = S, S - 1, and S + 1 are constructed. Using Wigner-Eckart algebra, all magnetic sublevels with M{sub S}= S, Horizontal-Ellipsis , -S for each multiplet of spin S are obtained. The spin-orbit operator is represented by a mean-field approximation to the full Breit-Pauli spin-orbit operator and is diagonalized over this N-particle basis. This is equivalent to a quasi-degenerate treatment of the spin-orbit interaction to all orders. Importantly, the excitation space spans all of the molecular multiplets that arise from the atomic Russell-Saunders terms. Hence, the method represents a rigorous first-principles approach to the complicated low-symmetry molecular multiplet problem met in L-edge X-ray absorption spectroscopy. In order to gain computational efficiency, as well as additional accuracy, the excitation space is restricted to single excitations and the configuration interaction matrix is slightly parameterized in order to account for dynamic correlation effects in an average way. To this end, it is advantageous to employ Kohn-Sham rather than Hartree-Fock orbitals thus defining the density functional theory/ROCIS method. However, the method can also be used in an entirely non-empirical fashion. Only three global empirical parameters are introduced and have been determined here for future application of the method to any system containing any transition metal. The three parameters were carefully calibrated using the L-edge X-ray absorption spectroscopy spectra of a test set of coordination complexes containing first row

Skyrme interaction and the properties of cold and hot neutron matter

International Nuclear Information System (INIS)

Mansour, H.M.M.; Hassan, M.Y.M.; Ramadan, S.

1986-08-01

The binding energy per particle, effective mass, magnetic susceptibility, etc for neutron matter are calculated using the Skyrme interaction SKII. Relativistic corrections to the non-relativistic Skyrme effective interaction to order 1/C 2 are also used to calculate the corrections for the binding energy of neutron matter. The correction is very small for small values of k h and increases as k n is increased. The thermal properties of neutron matter are calculated also using SKII force. The temperature dependences of the volume and spin pressure are determined. The results obtained show a similar trend as previous theoretical estimates by different methods of calculation. (author)

The relative importance of relativistic induced interactions in the beta decay of 170Tm

International Nuclear Information System (INIS)

Bogdan, D.; Cristu, M.I.; Holan, S.; Faessler, A.

1982-09-01

The log ft-values, the spectrum shape functions, and the beta-gamma angular correlation coefficients of the 170 Tm beta decay are computed in the framework of relativistic formfactor formalism using asymmetric rotor model wavefunctions. Main vector and axial vector hadron currents being strongly hindered, the relative importance of induced interaction matrix elements is accurately estimated. Good agreement with experiment is obtained for the beta decay observables when the main induced interaction terms were taken into account. The contribution of the pseudoscalar term was found insignificant. (authors)

The relativistic two-body potentials of constraint theory from summation of Feynman diagrams

OpenAIRE

Jallouli, H.; Sazdjian, H.

1996-01-01

The relativistic two-body potentials of constraint theory for systems composed of two spin-0 or two spin-1/2 particles are calculated, in perturbation theory, by means of the Lippmann-Schwinger type equation that relates them to the scattering amplitude. The cases of scalar and vector interactions with massless photons are considered. The two-photon exchange contributions, calculated with covariant propagators,are globally free of spurious infra-red singularities and produce at leading order ...

Application of relativistic distorted-wave method to electron-impact excitation of highly charged Fe XXIV ion embedded in weakly coupled plasmas

Science.gov (United States)

Chen, Zhanbin

2018-05-01

The process of excitation of highly charged Fe XXIV ion embedded in weakly coupled plasmas by electron impact is studied, together with the subsequent radiative decay. For the target structure, the calculation is performed using the multiconfiguration Dirac-Hartree-Fock method incorporating the Debye-Hückel potential for the electron-nucleus interaction. Fine-structure levels of the 1s22p and 1s2s2p configurations and the transition properties among these levels are presented over a wide range of screening parameters. For the collision dynamics, the distorted-wave method in the relativistic frame is adopted to include the effect of plasma background, in which the interparticle interactions in the system are described by screened interactions of the Debye-Hückel type. The continuum wave function of the projectile electron is obtained by solving the modified Dirac equations. The influence of plasma strength on the cross section, the linear polarization, and the angular distribution of x-ray photon emission are investigated in detail. Comparison of the present results with experimental data and other theoretical predictions, when available, is made.

Relativistic alpha-particles emitted in Fe-emulsion interactions at 1.7 A GeV

International Nuclear Information System (INIS)

Bhalla, K.B.; Chaudhry, M.; Lokanathan, S.; Grover, R.K.; Daftari, I.K.; Mangotra, L.L.; Rao, N.K.; Garpman, S.; Otterlund, I.

1981-02-01

Relativistic α-particles have been studied in 423 Fe-emulsion interactions at 1.7 A Gev. Comparisons of the observed angular distribution with that from 16 O-emulsion reactions at 2.1 A GeV reveal that more α particles are observed at large angles in the Fe-emulsion reactions. The α particles with large angles connot be explained by fragmentation from a clean cut spectator. Comparison of the experimental data with moving relativistic Boltzmann distributions shows that a single Boltzmann distribution cannot fit the fragmentation peak and the tail simultaneously. A thermal source (fireball) explaining the tail part of the distribution need to be formed by a mechanism other than simple clean cut participant-spectator picture. A large transverse momentum transfer to spectator before fragmentation may explain the tail. (author)

Characteristics of the interactions of 12 C, 22 Ne and 28 Si with emulsion nuclei accompanied with relativistic hadrons in the backward hemisphere at Dubna energy. Vol. 2

International Nuclear Information System (INIS)

El-Nadi, N.; Abdel-salam, A.; Mossa, N.A.; Krasnov, S.A.

1996-01-01

A detailed study of the characteristics of the interactions accompanied by relativistic hadrons in the backward hemisphere in the collisions of 12 C, 22 Ne and 26 Si projectiles with emulsion nuclei at incident momentum in the range (4.1-4.5) a GeV/C was carried out. For this purpose, random samples of 819, 3812, and 1209 events in case of 22 C, 22 Ne and 26 Si interactions are analyzed, respectively. The behaviour of the shower particles multiplicities, and the pseudorapidity distributions for the different interactions were investigated in terms of the number of emitted shower particles. The pseudorapidity distribution of the shower particles from the interactions accompanied by the emission of backward relativistic hadrons are found to be satisfactorily fitted by a single spindle Gaussian distribution. On the other hand, the pseudorapidity for the shower particles emitted in the interactions not accompanied by backward relativistic hadron are fitted by two Gaussian distributions with two distinct average values. The dispersion of the pseudorapidity distributions are insensitive to the number of the backward relativistic hadrons n b s . However, the average pseudorapidity decreases with increase of number of backward relativistic hadrons. The dependence of the average number of the shower particles produced in the backward and forward hemispheres on the projectile mass number and the impact parameter are also presented. The results yield quite interesting information regarding the production of such backward relativistic hadrons in heavy ions interactions. 9 figs., 3 tabs

Revised and extended analysis of the odd parity configurations of five-times ionized xenon: Xe VI

International Nuclear Information System (INIS)

Churilov, S.S.; Joshi, Y.N.

2000-01-01

Xenon spectra were recorded in the 300-1240 A region on a 3 m and a 10.7 normal incidence spectrograph using a modified triggered spark source. The spectrum of five-times ionized xenon (Xe VI) was investigated. The previous analysis of the 5s 2 5p,5s5p 2 , 5s 2 5d and 5s 2 6s configurations [V. Kaufman and J. Sugar (1987), A. Tauheed et al. At. (1992)] was confirmed. Three of the five levels of the 5p 3 configurations [ and 1995] and all the 5p 3 , 5s5p5d and 5s5p6s configurations levels [R. Sarmiento et al. (1999)] have been found to be erroneous. 53 new lines have been classified in the Xe VI spectrum. Twenty nine additional levels belonging to the 5p 3 , 5f, 6p and 5s5p5d odd configurations have been established. Hartree-Fock calculations with relativistic corrections (HFR) and least-square-fitted calculations (LSF) were carried out to interpret the spectrum. (orig.)

Relativistic quantum mechanics

International Nuclear Information System (INIS)

Ollitrault, J.Y.

1998-12-01

These notes form an introduction to relativistic quantum mechanics. The mathematical formalism has been reduced to the minimum in order to enable the reader to calculate elementary physical processes. The second quantification and the field theory are the logical followings of this course. The reader is expected to know analytical mechanics (Lagrangian and Hamiltonian), non-relativistic quantum mechanics and some basis of restricted relativity. The purpose of the first 3 chapters is to define the quantum mechanics framework for already known notions about rotation transformations, wave propagation and restricted theory of relativity. The next 3 chapters are devoted to the application of relativistic quantum mechanics to a particle with 0,1/5 and 1 spin value. The last chapter deals with the processes involving several particles, these processes require field theory framework to be thoroughly described. (A.C.)

Proton relativistic model; Modelo relativistico do proton

Energy Technology Data Exchange (ETDEWEB)

Araujo, Wilson Roberto Barbosa de

1996-12-31

In this dissertation, we present a model for the nucleon, which is composed by three relativistic quarks interacting through a contract force. The nucleon wave-function was obtained from the Faddeev equation in the null-plane. The covariance of the model under kinematical null-plane boots is discussed. The electric proton form-factor, calculated from the Faddeev wave-function, was in agreement with the data for low-momentum transfers and described qualitatively the asymptotic region for momentum transfers around 2 GeV. (author) 42 refs., 22 figs., 1 tab.

Multiwavelength Observations of Relativistic Jets from General Relativistic Magnetohydrodynamic Simulations

Directory of Open Access Journals (Sweden)

Richard Anantua

2018-03-01

Full Text Available This work summarizes a program intended to unify three burgeoning branches of the high-energy astrophysics of relativistic jets: general relativistic magnetohydrodynamic (GRMHD simulations of ever-increasing dynamical range, the microphysical theory of particle acceleration under relativistic conditions, and multiwavelength observations resolving ever-decreasing spatiotemporal scales. The process, which involves converting simulation output into time series of images and polarization maps that can be directly compared to observations, is performed by (1 self-consistently prescribing models for emission, absorption, and particle acceleration and (2 performing time-dependent polarized radiative transfer. M87 serves as an exemplary prototype for this investigation due to its prominent and well-studied jet and the imminent prospect of learning much more from Event Horizon Telescope (EHT observations this year. Synthetic observations can be directly compared with real observations for observational signatures such as jet instabilities, collimation, relativistic beaming, and polarization. The simplest models described adopt the standard equipartition hypothesis; other models calculate emission by relating it to current density or shear. These models are intended for application to the radio jet instead of the higher frequency emission, the disk and the wind, which will be subjects of future investigations.

Simulation of Molten Core-Concrete Interaction in oxide/metal stratified configuration with the TOLBIAC-ICB code

International Nuclear Information System (INIS)

Tourniaire, B.; Spindler, B.

2005-01-01

The frame of this work is the validation of the TOLBIAC-ICB code which is devoted to the simulation of Molten Core-Concrete Interaction (MCCI) for reactor safety analysis. Attention focuses here on the validation of TOLBIAC-ICB in configurations expected to be representative of the long term phase of MCCI i.e. during an interaction between an oxide/metal stratified corium melt and a concrete structure. Up to now the BETA tests performed at the Forschungszentrum Karlsruhe (FzK) are the only tests available to study such kind of interaction. The BETA tests are first described and the operating conditions are reminded. The TOLBIAC-ICB code is then briefly described, with emphasis on the models used for stratified configurations. The results of the simulations are discussed. A sensitivity study is also performed with the power generated in the oxide layer instead of the metal layer as in the test. This last calculation shows that the large axial ablation observed in the tests is probably due to the peculiar configuration of the test with input power in the bottom metal layer. Since in the reactor case the residual power would be mainly concentrated in the upper oxide layer, the conclusions of the BETA tests for the reactor applications, in term of axial ablation, must be derived with caution. (author)

The interaction of MnH(X 7Sigma+) with He: ab initio potential energy surface and bound states.

Science.gov (United States)

Turpin, Florence; Halvick, Philippe; Stoecklin, Thierry

2010-06-07

The potential energy surface of the ground state of the He-MnH(X (7)Sigma(+)) van der Waals complex is presented. Within the supermolecular approach of intermolecular energy calculations, a grid of ab initio points was computed at the multireference configuration interaction level using the aug-cc-pVQZ basis set for helium and hydrogen and the relativistic aug-cc-pVQZ-DK basis set for manganese. The potential energy surface was then fitted to a global analytical form which main features are discussed. As a first application of this potential energy surface, we present accurate calculations of bound energy levels of the (3)He-MnH and (4)He-MnH complexes.

The interaction of MnH(X 7Σ+) with He: Ab initio potential energy surface and bound states

Science.gov (United States)

Turpin, Florence; Halvick, Philippe; Stoecklin, Thierry

2010-06-01

The potential energy surface of the ground state of the He-MnH(X Σ7+) van der Waals complex is presented. Within the supermolecular approach of intermolecular energy calculations, a grid of ab initio points was computed at the multireference configuration interaction level using the aug-cc-pVQZ basis set for helium and hydrogen and the relativistic aug-cc-pVQZ-DK basis set for manganese. The potential energy surface was then fitted to a global analytical form which main features are discussed. As a first application of this potential energy surface, we present accurate calculations of bound energy levels of the H3e-MnH and H4e-MnH complexes.

Relativistic quantum mechanics of bosons

International Nuclear Information System (INIS)

Ghose, P.; Home, D.; Sinha Roy, M.N.

1993-01-01

We show that it is possible to use the Klein-Gordon, Proca and Maxwell formulations to construct multi-component relativistic configuration space wavefunctions of spin-0 and spin-1 bosons in an external field. These wavefunctions satisfy the first-order Kemmer-Duffin equation. The crucial ingredient is the use of the future-causal normal n μ (n μ n μ =1, n 0 >0) to the space-like hypersurfaces foliating space-time, inherent in the concept of a relativistic wavefunction, to construct a conserved future-causal probability current four-vector from the second-rank energy-momentum tensor, following Holland's prescription. The existence of a Hermitian position operator, localized solutions, compatibility with the second quantized theories and the question of interpretation are discussed. (orig.)

Classic Multi-Configuration-Dirac-Fock and Hartree-Fock-Relativistic methods integrated into a program package for the RAL-IBM mainframe with automatic comparative output

International Nuclear Information System (INIS)

Cowan, R.D.; Grant, I.P.; Fawcett, B.C.; Rose, S.J.

1985-11-01

A Multi-Configuration-Dirac-Fock (MCDF) computer program is adapted to interface with the Hartree-Fock-Relativistic (HFR) program for the RAL IBM mainframe computer. The two codes are integrated into a package which includes the Zeeman Laboratory Slater parameter optimisation routines as well as new RAL routines to further process the HFR and MCDF output. A description of the adaptions to MCDF and new output extensions is included in this report, and details are given regarding HFR FORTRAN subroutines, and lists of Job Control Language (JCL) files for the complete package. (author)

Relativistic continuum random phase approximation in spherical nuclei

International Nuclear Information System (INIS)

Daoutidis, Ioannis

2009-01-01

Covariant density functional theory is used to analyze the nuclear response in the external multipole fields. The investigations are based on modern functionals with zero range and density dependent coupling constants. After a self-consistent solution of the Relativistic Mean Field (RMF) equations for the nuclear ground states multipole giant resonances are studied within the Relativistic Random Phase Approximation (RRPA), the small amplitude limit of the time-dependent RMF. The coupling to the continuum is treated precisely by calculating the single particle Greens-function of the corresponding Dirac equation. In conventional methods based on a discretization of the continuum this was not possible. The residual interaction is derived from the same RMF Lagrangian. This guarantees current conservation and a precise decoupling of the Goldstone modes. For nuclei with open shells pairing correlations are taken into account in the framework of BCS theory and relativistic quasiparticle RPA. Continuum RPA (CRPA) presents a robust method connected with an astonishing reduction of the numerical effort as compared to conventional methods. Modes of various multipolarities and isospin are investigated, in particular also the newly discovered Pygmy modes in the vicinity of the neutron evaporation threshold. The results are compared with conventional discrete RPA calculations as well as with experimental data. We find that the full treatment of the continuum is essential for light nuclei and the study of resonances in the neighborhood of the threshold. (orig.)

Relativistic continuum random phase approximation in spherical nuclei

Energy Technology Data Exchange (ETDEWEB)

Daoutidis, Ioannis

2009-10-01

Covariant density functional theory is used to analyze the nuclear response in the external multipole fields. The investigations are based on modern functionals with zero range and density dependent coupling constants. After a self-consistent solution of the Relativistic Mean Field (RMF) equations for the nuclear ground states multipole giant resonances are studied within the Relativistic Random Phase Approximation (RRPA), the small amplitude limit of the time-dependent RMF. The coupling to the continuum is treated precisely by calculating the single particle Greens-function of the corresponding Dirac equation. In conventional methods based on a discretization of the continuum this was not possible. The residual interaction is derived from the same RMF Lagrangian. This guarantees current conservation and a precise decoupling of the Goldstone modes. For nuclei with open shells pairing correlations are taken into account in the framework of BCS theory and relativistic quasiparticle RPA. Continuum RPA (CRPA) presents a robust method connected with an astonishing reduction of the numerical effort as compared to conventional methods. Modes of various multipolarities and isospin are investigated, in particular also the newly discovered Pygmy modes in the vicinity of the neutron evaporation threshold. The results are compared with conventional discrete RPA calculations as well as with experimental data. We find that the full treatment of the continuum is essential for light nuclei and the study of resonances in the neighborhood of the threshold. (orig.)

Relativistic Random-Phase Approximation with Density-dependent Meson-nucleon Couplings at Finite Temperature

International Nuclear Information System (INIS)

Niu, Y.; Paar, N.; Vretenar, D.; Meng, J.

2009-01-01

The fully self-consistent relativistic random-phase approximation (RRPA) framework based on effective interactions with a phenomenological density dependence is extended to finite temperatures. The RRPA configuration space is built from the spectrum of single-nucleon states at finite temperature obtained by the temperature dependent relativistic mean field (RMF-T) theory based on effective Lagrangian with density dependent meson-nucleon vertex functions. As an illustration, the dependence of binding energy, radius, entropy and single particle levels on temperature for spherical nucleus 2 08P b is investigated in RMF-T theory. The finite temperature RRPA has been employed in studies of giant monopole and dipole resonances, and the evolution of resonance properties has been studied as a function of temperature. In addition, exotic modes of excitation have been systematically explored at finite temperatures, with an emphasis on the case of pygmy dipole resonances.(author)

Pair Natural Orbital Restricted Open-Shell Configuration Interaction (PNO-ROCIS) Approach for Calculating X-ray Absorption Spectra of Large Chemical Systems.

Science.gov (United States)

Maganas, Dimitrios; DeBeer, Serena; Neese, Frank

2018-02-08

In this work, the efficiency of first-principles calculations of X-ray absorption spectra of large chemical systems is drastically improved. The approach is based on the previously developed restricted open-shell configuration interaction singles (ROCIS) method and its parametrized version, based on a density functional theory (DFT) ground-state determinant ROCIS/DFT. The combination of the ROCIS or DFT/ROCIS methods with the well-known machinery of the pair natural orbitals (PNOs) leads to the new PNO-ROCIS and PNO-ROCIS/DFT variants. The PNO-ROCIS method can deliver calculated metal K-, L-, and M-edge XAS spectra orders of magnitude faster than ROCIS while maintaining an accuracy with calculated spectral parameters better than 1% relative to the original ROCIS method (referred to as canonical ROCIS). The method is of a black box character, as it does not require any user adjustments, while it scales quadratically with the system size. It is shown that for large systems, the size of the virtual molecular orbital (MO) space is reduced by more than 90% with respect to the canonical ROCIS method. This allows one to compute the X-ray absorption spectra of a variety of large "real-life" chemical systems featuring hundreds of atoms using a first-principles wave-function-based approach. Examples chosen from the fields of bioinorganic and solid-state chemistry include the Co K-edge XAS spectrum of aquacobalamin [H 2 OCbl] + , the Fe L-edge XAS spectrum of deoxymyoglobin (DMb), the Ti L-edge XAS spectrum of rutile TiO 2 , and the Fe M-edge spectrum of α-Fe 2 O 3 hematite. In the largest calculations presented here, molecules with more than 700 atoms and cluster models with more than 50 metal centers were employed. In all the studied cases, very good to excellent agreement with experiment is obtained. It will be shown that the PNO-ROCIS method provides an unprecedented performance of wave-function-based methods in the field of computational X-ray spectroscopy.

Relativistic classical and quantum dynamics in intense crossed laser beams of various polarizations

Directory of Open Access Journals (Sweden)

M. Verschl

2007-02-01

Full Text Available The dynamics of an electron in crossed laser fields is investigated analytically. Two different standing wave configurations are compared. The counterpropagating laser waves are either linearly or circularly polarized. Both configurations have in common that there are one-dimensional trajectories on which the electron can oscillate with vanishing Lorentz force. The dynamics is analyzed for the situations when the electron moves in the vicinity of these ideal axes. If the laser intensities imply nonrelativistic electron dynamics, the system is described quantum mechanically. A semiclassical treatment renders the strongly relativistic regime accessible as well. To describe relativistic wave packets, the results of the classical analysis are employed for a Monte Carlo ensemble. This allows for a comparison of the wave packet dynamics for both configurations in the strongly relativistic regime. It is found for certain cases that relativity slows down the dynamics, i.e., for higher laser intensities, wave packet spreading and the drift away from the ideal axis of vanishing Lorentz force are shown to be increasingly suppressed.

Studies of the relativistic electron source and related phenomena in Petawatt Laser matter interactions

International Nuclear Information System (INIS)

Key, M.H.; Campbell, E.M.; Cowan, T.E.; Hatchett, S.P.; Henry, E.A.; Koch, J.A.; Landgon, A.B.; Lasinski, B.F.; Lee, R.W.; MacKinnon, A.; Offenberger, A.; Pennington, D.M.; Perry, M.D.; Sangster, T.C.; Yasuike, K.; Snavely, R.; Roth, M.; Phillips, T.W.; Stoyer, M.A.; Wilks, S.C.; Singh, M.S.

1999-01-01

The interaction of laser radiation with solid targets at 1 petawatt power and intensity up to 3x10 20 Wcm -2 has been studied with emphasis on relativistic electrons and high energy ions. Secondary effects including Bremsstrahlung radiation, nuclear interactions and heating have been characterized. A collimated beam of protons with up to 55 MeV energy is emitted normal to the rear surface of thin targets and its characteristics and origin are discussed. The significance of the data for radiography, fast ignition and proton beam applications is summarized

Relativistic Chiral Mean Field Model for Finite Nuclei

Science.gov (United States)

Ogawa, Y.; Toki, H.; Tamenaga, S.; Haga, A.

2009-08-01

We present a relativistic chiral mean field (RCMF) model, which is a method for the proper treatment of pion-exchange interaction in the nuclear many-body problem. There the dominant term of the pionic correlation is expressed in two-particle two-hole (2p-2h) states with particle-holes having pionic quantum number, J^{π}. The charge-and-parity-projected relativistic mean field (CPPRMF) model developed so far treats surface properties of pionic correlation in 2p-2h states with J^{π} = 0^{-} (spherical ansatz). We extend the CPPRMF model by taking 2p-2h states with higher spin quantum numbers, J^{π} = 1^{+}, 2^{-}, 3^{+}, ... to describe the full strength of the pionic correlation in the intermediate range (r > 0.5 fm). We apply the RCMF model to the ^{4}He nucleus as a pilot calculation for the study of medium and heavy nuclei. We study the behavior of energy convergence with the pionic quantum number, J^{π}, and find convergence around J^{π}_{max} = 6^{-}. We include further the effect of the short-range repulsion in terms of the unitary correlation operator method (UCOM) for the central part of the pion-exchange interaction. The energy contribution of about 50% of the net two-body interaction comes from the tensor part and 20% comes from the spin-spin central part of the pion-exchange interaction.}

Electronic structure of Ge-2 and Ge-2 and thermodynamic properties of Ge-2 from all electron ab initio investigations and Knudsen effusion mass spectroscopic measurements

DEFF Research Database (Denmark)

Shim, Irene; Baba, M. Sai; Gingerich, K.A.

2002-01-01

The low-lying states of the molecule Ge-2 and of the ion Ge-2(-) have been investigated by all electron ab initio multiconfiguration self-consistent field (CASSCF) and multi-reference configuration interaction (MRCI) calculations. The relativistic corrections for the Darwin contact term and for t......The low-lying states of the molecule Ge-2 and of the ion Ge-2(-) have been investigated by all electron ab initio multiconfiguration self-consistent field (CASSCF) and multi-reference configuration interaction (MRCI) calculations. The relativistic corrections for the Darwin contact term...... excited states are presented. Thermal functions based on the theoretically determined molecular parameters were used to derive the thermodynamic properties of the Ge-2 molecule from new mass spectrometric equilibrium data. The literature value for the dissociation energy of Ge-2 has been re...

Random phase approximation in relativistic approach

International Nuclear Information System (INIS)

Ma Zhongyu; Yang Ding; Tian Yuan; Cao Ligang

2009-01-01

Some special issues of the random phase approximation(RPA) in the relativistic approach are reviewed. A full consistency and proper treatment of coupling to the continuum are responsible for the successful application of the RPA in the description of dynamical properties of finite nuclei. The fully consistent relativistic RPA(RRPA) requires that the relativistic mean filed (RMF) wave function of the nucleus and the RRPA correlations are calculated in a same effective Lagrangian and the consistent treatment of the Dirac sea of negative energy states. The proper treatment of the single particle continuum with scattering asymptotic conditions in the RMF and RRPA is discussed. The full continuum spectrum can be described by the single particle Green's function and the relativistic continuum RPA is established. A separable form of the paring force is introduced in the relativistic quasi-particle RPA. (authors)

Full four-component relativistic calculations of the one-bond 77Se-13C spin-spin coupling constants in the series of selenium heterocycles and their parent open-chain selenides.

Science.gov (United States)

Rusakov, Yury Yu; Rusakova, Irina L; Krivdin, Leonid B

2014-05-01

Four-component relativistic calculations of (77)Se-(13)C spin-spin coupling constants have been performed in the series of selenium heterocycles and their parent open-chain selenides. It has been found that relativistic effects play an essential role in the selenium-carbon coupling mechanism and could result in a contribution of as much as 15-25% of the total values of the one-bond selenium-carbon spin-spin coupling constants. In the overall contribution of the relativistic effects to the total values of (1)J(Se,C), the scalar relativistic corrections (negative in sign) by far dominate over the spin-orbit ones (positive in sign), the latter being of less than 5%, as compared to the former (ca 20%). A combination of nonrelativistic second-order polarization propagator approach (CC2) with the four-component relativistic density functional theory scheme is recommended as a versatile tool for the calculation of (1)J(Se,C). Solvent effects in the values of (1)J(Se,C) calculated within the polarizable continuum model for the solvents with different dielectric constants (ε 2.2-78.4) are next to negligible decreasing negative (1)J(Se,C) in absolute value by only about 1 Hz. The use of the locally dense basis set approach applied herewith for the calculation of (77)Se-(13)C spin-spin coupling constants is fully justified resulting in a dramatic decrease in computational cost with only 0.1-0.2-Hz loss of accuracy. Copyright © 2014 John Wiley & Sons, Ltd.

Control configuration selection for bilinear systems via generalised Hankel interaction index array

DEFF Research Database (Denmark)

Shaker, Hamid Reza; Tahavori, Maryamsadat

2015-01-01

configuration selection. It is well known that a suitable control configuration selection is an important prerequisite for a successful industrial control. In this paper the problem of control configuration selection for multiple-input and multiple-output (MIMO) bilinear processes is addressed. First...... way, an iterative method for solving the generalised Sylvester equation is proposed. The generalised cross-gramian is used to form the generalised Hankel interaction index array. The generalised Hankel interaction index array is used for control configuration selection of MIMO bilinear processes. Most......Decentralised and partially decentralised control strategies are very popular in practice. To come up with a suitable decentralised or partially decentralised control structure, it is important to select the appropriate input and output pairs for control design. This procedure is called control...

Studies of nuclear matter under extreme conditions: Heavy-ion interactions at ultra-relativistic energies

Energy Technology Data Exchange (ETDEWEB)

Nystrand, J

1996-10-01

The charged particle production in ultra-relativistic nucleus-nucleus collisions in the energy range 4-200 A GeV has been studied. Two different experimental techniques have been utilized: nuclear emulsions and multi-step avalanche chambers. The performance of the chambers in the experiment as well as the analysis of the chamber data are described in the thesis. The reconstructed particle momenta have been used to study transverse momentum distribution of negatively charged particles, and to perform intensity interferometry analyses in order to determine the source size and study the time-evolution of the interactions. Multiplicity and pseudorapidity distributions of singly charged particles obtained from interactions in nuclear emulsion have been studied. Simulations have been performed with various Monte-Carlo models, and particularly the effects of the hadronic rescattering have been studied. The results of the analysis have illustrated the great importance of the nuclear geometry in ultra-relativistic nucleus-nucleus collisions. Based on gaussian parametrizations a method of predicting the pseudorapidity distributions in systems of different sizes and at different energies has been developed. Furthermore, the multiplicity and angular distributions of slow, target associated particles have been analyzed. 99 refs, 19 figs.

Studies of nuclear matter under extreme conditions: Heavy-ion interactions at ultra-relativistic energies

International Nuclear Information System (INIS)

Nystrand, J.

1996-10-01

The charged particle production in ultra-relativistic nucleus-nucleus collisions in the energy range 4-200 A GeV has been studied. Two different experimental techniques have been utilized: nuclear emulsions and multi-step avalanche chambers. The performance of the chambers in the experiment as well as the analysis of the chamber data are described in the thesis. The reconstructed particle momenta have been used to study transverse momentum distribution of negatively charged particles, and to perform intensity interferometry analyses in order to determine the source size and study the time-evolution of the interactions. Multiplicity and pseudorapidity distributions of singly charged particles obtained from interactions in nuclear emulsion have been studied. Simulations have been performed with various Monte-Carlo models, and particularly the effects of the hadronic rescattering have been studied. The results of the analysis have illustrated the great importance of the nuclear geometry in ultra-relativistic nucleus-nucleus collisions. Based on gaussian parametrizations a method of predicting the pseudorapidity distributions in systems of different sizes and at different energies has been developed. Furthermore, the multiplicity and angular distributions of slow, target associated particles have been analyzed. 99 refs, 19 figs

Chaos and maps in relativistic rynamical systems

Directory of Open Access Journals (Sweden)

L. P. Horwitz

2000-01-01

Full Text Available The basic work of Zaslavskii et al showed that the classical non-relativistic electromagnetically kicked oscillator can be cast into the form of an iterative map on the phase space; the resulting evolution contains a stochastic flow to unbounded energy. Subsequent studies have formulated the problem in terms of a relativistic charged particle in interaction with the electromagnetic field. We review the structure of the covariant Lorentz force used to study this problem. We show that the Lorentz force equation can be derived as well from the manifestly covariant mechanics of Stueckelberg in the presence of a standard Maxwell field, establishing a connection between these equations and mass shell constraints. We argue that these relativistic generalizations of the problem are intrinsically inaccurate due to an inconsistency in the structure of the relativistic Lorentz force, and show that a reformulation of the relativistic problem, permitting variations (classically in both the particle mass and the effective “mass” of the interacting electromagnetic field, provides a consistent system of classical equations for describing such processes.

Isotope shift and configuration interaction in U I

International Nuclear Information System (INIS)

King, W.H.

1979-01-01

Recent calculations by Rajnak and Fred (J. Opt. Soc. Am.; 67:1314 (1977)) show that the transitions studied by Gagne et al (J. Opt. Soc. Am.; 66:1415 (1976)) have upper levels of mixed configurations. The amount of mixing and the probability of mass shifts due to 5f electrons is discussed. (author)

Radiative electron capture studied in relativistic heavy-ion atom collisions

International Nuclear Information System (INIS)

Stoehlker, T.; Kozhuharov, C.; Mokler, P.H.; Warczak, A.; Bosch, F.; Geissel, H.; Moshammer, R.; Scheidenberger, C.; Eichler, J.; Shirai, T.; Stachura, Z.; Rymuza, P.

1994-08-01

The process of Radiative Electron Capture (REC) in relativistic collisions of high-Z ions with low-Z gaseous and solid targets is studied experimentally and theoretically. The observed X-ray spectra are analysed with respect to photon angular distributions as well as to total K-REC cross sections. The experimental results for angle-differential cross sections are well-reproduced by exact relativistic calculations which yield significant deviations from standard sin 2 θ distributions. Total cross sections for K-REC are shown to follow a simple scaling rule obtained from exact relativistic calculations as well as from a non-relativistic dipole approximation. The agreement between these different theoretical approaches must be regarded as fortuitous, but it lends support to the use of the non-relativistic approach for practical purposes. (orig.)

Multiphoton ionization of many-electron atoms and highly-charged ions in intense laser fields: a relativistic time-dependent density functional theory approach

Science.gov (United States)

Tumakov, Dmitry A.; Telnov, Dmitry A.; Maltsev, Ilia A.; Plunien, Günter; Shabaev, Vladimir M.

2017-10-01

We develop an efficient numerical implementation of the relativistic time-dependent density functional theory (RTDDFT) to study multielectron highly-charged ions subject to intense linearly-polarized laser fields. The interaction with the electromagnetic field is described within the electric dipole approximation. The resulting time-dependent relativistic Kohn-Sham (RKS) equations possess an axial symmetry and are solved accurately and efficiently with the help of the time-dependent generalized pseudospectral method. As a case study, we calculate multiphoton ionization probabilities of the neutral argon atom and argon-like xenon ion. Relativistic effects are assessed by comparison of our present results with existing non-relativistic data.

The time-dependent relativistic mean-field theory and the random phase approximation

International Nuclear Information System (INIS)

Ring, P.; Ma, Zhong-yu; Van Giai, Nguyen; Vretenar, D.; Wandelt, A.; Cao, Li-gang

2001-01-01

The Relativistic Random Phase Approximation (RRPA) is derived from the Time-Dependent Relativistic Mean-Field (TD RMF) theory in the limit of small amplitude oscillations. In the no-sea approximation of the RMF theory, the RRPA configuration space includes not only the usual particle-hole ph-states, but also αh-configurations, i.e. pairs formed from occupied states in the Fermi sea and empty negative-energy states in the Dirac sea. The contribution of the negative-energy states to the RRPA matrices is examined in a schematic model, and the large effect of Dirac-sea states on isoscalar strength distributions is illustrated for the giant monopole resonance in 116 Sn. It is shown that, because the matrix elements of the time-like component of the vector-meson fields which couple the αh-configurations with the ph-configurations are strongly reduced with respect to the corresponding matrix elements of the isoscalar scalar meson field, the inclusion of states with unperturbed energies more than 1.2 GeV below the Fermi energy has a pronounced effect on giant resonances with excitation energies in the MeV region. The influence of nuclear magnetism, i.e. the effect of the spatial components of the vector fields is examined, and the difference between the nonrelativistic and relativistic RPA predictions for the nuclear matter compression modulus is explained

Biquaternions and relativistic kinematics

International Nuclear Information System (INIS)

Bogush, A.A.; Kurochkin, Yu.A.; Fedorov, F.I.

1979-01-01

The problems concerning the use of quaternion interpretation of the Lorentz group vector parametrization are considered for solving relativistic kinematics problems. A vector theory convenient for describing the characteristic features of the Lobachevsky space is suggested. The kinematics of elementary particle scattering is investigated on the basis of this theory. A synthesis of vector parametrization and of quaternion calculation has been shown to lead to natural formulation of the theory of vectors in the three-dimensional Lobachevsky space, realized on mass hyperboloids of relativistic particles

Calculation of emission and absorption spectra of LTE plasma by the STA method

International Nuclear Information System (INIS)

Oreg, A.B.J.; Goldstein, W.H.

1991-01-01

Recent improvements in the Super Transition Array (STA) method for calculating Bound-Bound (BB) and Bound-Free (BF) emission and absorption spectra for LTE plasma are described and illustrated. The method accounts for all possible BB and BF radiative transitions in the plasma. Full detailed first order quantum relativistic treatment is used for calculating transition energies and probabilities. The enormous number of configurations are divided into sets of superconfigurations comprised of a collection of energetically grouped configurations to a specific one-electron transition is then represented by a Gaussian whose moments (total intensity, average energy and variance) are calculated accurately using a technique that bypasses the necessity of direct summation over all the levels involved. The calculation of these moments involves the populations of the configurations given by their statistical weights and the Boltzmann factor. For each configuration within the superconfiguration the authors use zeroeth order energies in the Boltzmann factor corrected by a superconfiguration averaged first order term. The structure of the spectrum is increasingly revealed by splitting each STA into a number of smaller STAs. When the spectrum converges it describes the detailed UTA structure, where each configuration-to-configuration array is represented by a separate Gaussian with first order energy in the Boltzmann factor. Convergence is reached with only a few thousand STAs, at most, which makes the calculations practical. It should be pointed out that in this treatment the STA moments are obtained by summing over all level-to-level transitions, rather than configuration-to-configuration average transitions. The authors also take into account orbital relaxation by calculating orbitals and energies for each superconfiguration in its own, optimized potential

Roles of antinucleon degrees of freedom in the relativistic random phase approximation

Science.gov (United States)

Kurasawa, Haruki; Suzuki, Toshio

2015-11-01

The roles of antinucleon degrees of freedom in the relativistic random phase approximation (RPA) are investigated. The energy-weighted sum of the RPA transition strengths is expressed in terms of the double commutator between the excitation operator and the Hamiltonian, as in nonrelativistic models. The commutator, however, should not be calculated in the usual way in the local field theory, because, otherwise, the sum vanishes. The sum value obtained correctly from the commutator is infinite, owing to the Dirac sea. Most of the previous calculations take into account only some of the nucleon-antinucleon states, in order to avoid divergence problems. As a result, RPA states with negative excitation energy appear, which make the sum value vanish. Moreover, disregarding the divergence changes the sign of nuclear interactions in the RPA equation that describes the coupling of the nucleon particle-hole states with the nucleon-antinucleon states. Indeed, the excitation energies of the spurious state and giant monopole states in the no-sea approximation are dominated by these unphysical changes. The baryon current conservation can be described without touching the divergence problems. A schematic model with separable interactions is presented, which makes the structure of the relativistic RPA transparent.

Second quantization of classical nonlinear relativistic field theory. Pt. 2

International Nuclear Information System (INIS)

Balaban, T.

1976-01-01

The construction of a relativistic interacting local quantum field is given in two steps: first the classical nonlinear relativistic field theory is written down in terms of Poisson brackets, with initial conditions as canonical variables: next a representation of Poisson bracket Lie algebra by means of linear operators in the topological vector space is given and an explicit form of a local interacting relativistic quantum field PHI is obtained. (orig./BJ) [de

Relativistic Binaries in Globular Clusters

Directory of Open Access Journals (Sweden)

Matthew J. Benacquista

2013-03-01

Full Text Available Galactic globular clusters are old, dense star systems typically containing 10^4 – 10^6 stars. As an old population of stars, globular clusters contain many collapsed and degenerate objects. As a dense population of stars, globular clusters are the scene of many interesting close dynamical interactions between stars. These dynamical interactions can alter the evolution of individual stars and can produce tight binary systems containing one or two compact objects. In this review, we discuss theoretical models of globular cluster evolution and binary evolution, techniques for simulating this evolution that leads to relativistic binaries, and current and possible future observational evidence for this population. Our discussion of globular cluster evolution will focus on the processes that boost the production of tight binary systems and the subsequent interaction of these binaries that can alter the properties of both bodies and can lead to exotic objects. Direct N-body integrations and Fokker–Planck simulations of the evolution of globular clusters that incorporate tidal interactions and lead to predictions of relativistic binary populations are also discussed. We discuss the current observational evidence for cataclysmic variables, millisecond pulsars, and low-mass X-ray binaries as well as possible future detection of relativistic binaries with gravitational radiation.

Relativistic finite-temperature Thomas-Fermi model

Science.gov (United States)

Faussurier, Gérald

2017-11-01

We investigate the relativistic finite-temperature Thomas-Fermi model, which has been proposed recently in an astrophysical context. Assuming a constant distribution of protons inside the nucleus of finite size avoids severe divergence of the electron density with respect to a point-like nucleus. A formula for the nuclear radius is chosen to treat any element. The relativistic finite-temperature Thomas-Fermi model matches the two asymptotic regimes, i.e., the non-relativistic and the ultra-relativistic finite-temperature Thomas-Fermi models. The equation of state is considered in detail. For each version of the finite-temperature Thomas-Fermi model, the pressure, the kinetic energy, and the entropy are calculated. The internal energy and free energy are also considered. The thermodynamic consistency of the three models is considered by working from the free energy. The virial question is also studied in the three cases as well as the relationship with the density functional theory. The relativistic finite-temperature Thomas-Fermi model is far more involved than the non-relativistic and ultra-relativistic finite-temperature Thomas-Fermi models that are very close to each other from a mathematical point of view.

Is the relativistic approach really useful to nuclear reactions?

CERN Document Server

Miyazaki, K

2003-01-01

We have reconsidered the non-relativistic distorted-wave t-matrix approximation (NR-DWTA) for proton knockout (p,2p) reaction using modern high-quality phenomenological optical potentials and NN t-matrix. We have calculated 40Ca(p,2p) reactions at T_LAB=200MeV and compared the results with the relativistic distorted-wave impulse approximation (RDWIA) calculations. It is found that the NR-DWTA is superior to the RDWIA in consistent description of the cross section and the analyzing power. An immediate relativistic extension of the DWIA to the nuclear reaction has a problem.

Quest of halo in 31Ne using Glauber model formalism with deformed relativistic mean field density

International Nuclear Information System (INIS)

Sharma, Mahesh K.; Patra, S.K.

2012-01-01

The advancement of radio active ion beam (RIB) explored the structure of exotic nuclei, which are away from the β stability line. Such nuclei with weak binding lie at the limit of stability and exhibit some fascinating phenomena. One of them is the formation of one or more nucleon halo structure. It is well established that the interaction cross section of halo nuclei like 11 Li, 11 Be and 19 C show anomalously large interaction cross sections and matter radius than that of their neighboring nuclei. Some recent investigations for 31 Ne predict that has a halo nature. The first experimental evidence also suggests 31 Ne as a halo candidate. The isotope 31 Ne having N=21, which breaks the shell closer structure as a consequence of deformation associated with the strong intruder configuration and having special interest, because it lie at island of inversion. Here we apply the well known Glauber approach with conjunction of deformed relativistic mean field densities of projectile and target nuclei. It is to be noted that Panda et al has done the similar calculation using a spherical density

Ab initio calculation of the electronic structures of the 7∑+ ground and A 7Π and a 5∑+ excited states of MnH

Science.gov (United States)

Tomonari, Mutsumi; Nagashima, Umpei; Hirano, Tsuneo

2009-04-01

Electronic structures and molecular constants of the ground ∑7+ and low-lying A 7Π and a ∑5+ electronic excited states of the MnH molecule were studied by multireference single and double excitation configuration interaction (MR-SDCI) with Davidson's correction (+Q) calculations under exact C∞v symmetry using Slater-type basis sets. To correctly describe the ∑7+ electronic ground state, X ∑7+, at the MR-SDCI+Q calculation, we employed a large number of reference configurations in terms of the state-averaged complete active space self-consistent field (CASSCF) orbitals, taking into account the contribution from the B ∑7+ excited state. The A 7Π and a ∑5+ states can well be described by the MR-SDCI wave functions based on the CASSCF orbitals obtained for the lowest state only. In the MR-SDCI+Q, calculations of the X ∑7+, A 7Π, and a ∑5+ states required 16, 7, and 17 reference configurations, respectively. Molecular constants, i.e., re and ωe of these states and excitation energy from the X ∑7+ state, obtained at the MR-SDCI+Q level, showed a good agreement with experimental values. The small remaining differences may be accounted for by taking relativistic effects into account.

Ab initio calculation of the electronic structures of the (7)Sigma+ ground and A (7)Pi and a (5)Sigma+ excited states of MnH.

Science.gov (United States)

Tomonari, Mutsumi; Nagashima, Umpei; Hirano, Tsuneo

2009-04-21

Electronic structures and molecular constants of the ground (7)Sigma(+) and low-lying A (7)Pi and a (5)Sigma(+) electronic excited states of the MnH molecule were studied by multireference single and double excitation configuration interaction (MR-SDCI) with Davidson's correction (+Q) calculations under exact C(infinity v) symmetry using Slater-type basis sets. To correctly describe the (7)Sigma(+) electronic ground state, X (7)Sigma(+), at the MR-SDCI+Q calculation, we employed a large number of reference configurations in terms of the state-averaged complete active space self-consistent field (CASSCF) orbitals, taking into account the contribution from the B (7)Sigma(+) excited state. The A (7)Pi and a (5)Sigma(+) states can well be described by the MR-SDCI wave functions based on the CASSCF orbitals obtained for the lowest state only. In the MR-SDCI+Q, calculations of the X (7)Sigma(+), A (7)Pi, and a (5)Sigma(+) states required 16, 7, and 17 reference configurations, respectively. Molecular constants, i.e., r(e) and omega(e) of these states and excitation energy from the X (7)Sigma(+) state, obtained at the MR-SDCI+Q level, showed a good agreement with experimental values. The small remaining differences may be accounted for by taking relativistic effects into account.

A systematic study of even-even nuclei up to the drip lines within the relativistic mean field framework

International Nuclear Information System (INIS)

Hirata, D.; Sumiyoshi, K.; Tanihata, I.; Sugahara, Y.; Tachibana, T.; Toki, H.

1997-01-01

We apply the relativistic mean field theory to study the ground state properties of about 2000 even-even nuclei from Z=8 to Z=120 up to the proton and neutron drip lines. The calculations have been done under the axial symmetry assumption and a quadratic constraint method in order to obtain all possible ground state configurations. We do not take into account the pairing correlation in the present study. The calculations are performed with the TMA parameter set. We explore the generaI trend of masses, radii and deformations in the whole region of the nuclear chart. Using the masses obtained from RMF theory, we calculate the r-process abundances and the r-process path. (orig.)

Radiative transitions of B and Bs mesons in a non relativistic quark model with hulthen potential

International Nuclear Information System (INIS)

D'Souza, Praveen P.; Monteiro, A.P.; Vijaya Kumar, K.B.

2017-01-01

Heavy light mesons composed of one heavy quark and one light quark. They are the only mesons containing quarks of the third generation. Which has contributed enormously to our understanding of elementary particles and their interactions. In our calculation we get variational parameter for different heavy-light mesons. Having variational parameter eigen energy will be obtained. For meson system, the Hulthen term acts like a Coulombic term. The spin dependent potential from One Gluon Exchange Potential (OGEP) is introduced. The goal of the present work is to obtain the decay widths and understand the uncertainties in the calculation in the frame work of non-relativistic quark models. In the non-relativistic models this is satisfied for the c, b and t quarks

Relativistic differential-difference momentum operators and noncommutative differential calculus

International Nuclear Information System (INIS)

Mir-Kasimov, R.M.

2011-01-01

Full text: (author)The relativistic kinetic momentum operators are introduced in the framework of the Quantum Mechanics in the relativistic configuration space (RCS). These operators correspond to the half of the non-Euclidean distance in the Lobachevsky momentum space. In terms of kinetic momentum operators the relativistic kinetic energy is separated from the total Hamiltonian. The role of the plane wave (wave function of the motion with definite value of momentum and energy) plays the generation function for the matrix elements of the unitary irreps of Lorentz group (generalized Jacobi polynomials). The kinetic momentum operators are the interior derivatives in the framework of the non-commutative differential calculus over the commutative algebra generated by the coordinate functions over the RCS

Relativistic shocks and particle acceleration

International Nuclear Information System (INIS)

Heavens, A.F.

1988-01-01

In this paper, we investigate the fluid dynamics of relativistic shock waves, and use the results to calculate the spectral index of particles accelerated by the Fermi process in such shocks. We have calculated the distributions of Fermi-accelerated particles at shocks propagating into cold proton-electron plasma and also cold electron-positron plasma. We have considered two different power spectra for the scattering waves, and find, in contrast to the non-relativistic case, that the spectral index of the accelerated particles depends on the wave power spectrum. On the assumption of thermal equilibrium both upstream and downstream, we present some useful fits for the compression ratio of shocks propagating at arbitrary speeds into gas of any temperature. (author)

Contribution of relativistic quantum chemistry to electron’s electric dipole moment for CP violation

Energy Technology Data Exchange (ETDEWEB)

Abe, M., E-mail: minoria@tmu.ac.jp; Gopakumar, G., E-mail: gopakumargeetha@gmail.com; Hada, M., E-mail: hada@tmu.ac.jp [Tokyo Metropolitan University, 1-1, Minami-Osawa, Hachioji-city, Tokyo 192-0397 (Japan); JST, CREST, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); Das, B. P., E-mail: das@iiap.ernet.in [Indian Institute of Astrophysics, Bangalore 560 034 (India); Tatewaki, H., E-mail: htatewak@nsc.nagoya-cu.ac.jp [Graduate School of Natural Sciences, Nagoya City University, Nagoya, Aichi 467-8501 (Japan); Mukherjee, D., E-mail: pcdm@iacs.res.in [Raman Center of Atomic, Molecular and Optical Sciences, IACS, Kolkata 700 032 (India)

2015-12-31

The search for the electric dipole moment of the electron (eEDM) is important because it is a probe of Charge Conjugation-Parity (CP) violation. It can also shed light on new physics beyond the standard model. It is not possible to measure the eEDM directly. However, the interaction energy involving the effective electric field (E{sub eff}) acting on an electron in a molecule and the eEDM can be measured. This quantity can be combined with E{sub eff}, which is calculated by relativistic molecular orbital theory to determine eEDM. Previous calculations of E{sub eff} were not sufficiently accurate in the treatment of relativistic or electron correlation effects. We therefore developed a new method to calculate E{sub eff} based on a four-component relativistic coupled-cluster theory. We demonstrated our method for YbF molecule, one of the promising candidates for the eEDM search. Using very large basis set and without freezing any core orbitals, we obtain a value of 23.1 GV/cm for E{sub eff} in YbF with an estimated error of less than 10%. The error is assessed by comparison of our calculations and experiments for two properties relevant for E{sub eff}, permanent dipole moment and hyperfine coupling constant. Our method paves the way to calculate properties of various kinds of molecules which can be described by a single-reference wave function.

Coherent vector-meson photoproduction with nuclear breakup in relativistic heavy-ion collisions

International Nuclear Information System (INIS)

Baltz, Anthony J.; Klein, Spencer R.; Nystrand, Joakim

2002-01-01

Relativistic heavy ions are copious sources of virtual photons. The large photon flux gives rise to a substantial photonuclear interaction probability at impact parameters where no hadronic interactions can occur. Multiple photonuclear interactions in a single collision are possible. In this Letter, we use mutual Coulomb excitation of both nuclei as a tag for moderate-impact-parameter collisions. We calculate the cross section for coherent vector-meson production accompanied by mutual excitation and show that the median impact parameter is much smaller than for untagged production. The vector-meson rapidity and transverse-momentum distribution are very different from untagged exclusive vector-meson production

Isoscalar giant resonances in a relativistic model

International Nuclear Information System (INIS)

L'Huillier, M.; Nguyen Van Giai.

1988-07-01

Isoscalar giant resonances in finite nuclei are studied in a relativistic Random Phase Approximation (RRPA) approach. The model is self-consistent in the sense that one set of coupling constants generates the Dirac-Hartree single-particle spectrum and the residual particle-hole interaction. The RRPA is used to calculate response functions of multipolarity L = 0,2,3, and 4 in light and medium nuclei. It is found that monopole and quadrupole modes exhibit a collective character. The peak energies are overestimated, but not as much as one might think if the bulk properties (compression modulus, effective mass) were the only relevant quantities

Relativistic reversal of the ponderomotive force in a standing laser wave

International Nuclear Information System (INIS)

Pokrovsky, A.L.; Kaplan, A.E.

2005-01-01

Effect of relativistic reversal of the ponderomotive force (PF), reported earlier for a collinear configuration of electron and laser standing wave [A. E. Kaplan and A. L. Pokrovsky, Phys. Rev. Lett., 95, 053601 (2005)], is studied here theoretically for various types of polarizations of the laser beam. We demonstrated that the collinear configuration, in which the laser wave is linearly polarized with electric field E-vector parallel to the initial electron momentum p-vector 0 , is the optimal configuration for the relativistic reversal. In that case, the transverse PF reverses its direction when the incident momentum is p 0 =mc. The reversal effect vanishes in the cases of circular and linear with E-vector perpendicular p-vector 0 polarizations. We have discovered, however, that the counter-rotating circularly polarized standing waves develop attraction and repulsion areas along the axis of laser, in the laser field whose intensity is homogeneous in that axis, i.e., has no field gradient

Pion propagator in relativistic quantum field theories of the nuclear many-body problem

International Nuclear Information System (INIS)

Matsui, T.; Serot, B.D.

1982-01-01

Pion interactions in the nuclear medium are studied using renormalizable relativistic quantum field theories. Previous studies using pseudoscalar πN coupling encountered difficulties due to the large strength of the πNN vertex. We therefore formulate renormalizable field theories with pseudovector πN coupling using techniques introduced by Weinberg and Schwinger. Calculations are performed for two specific models; the scalar-vector theory of Walecka, extended to include π and rho mesons in a non-chiral fashion, and the linear sigma-model with an additional neutral vector meson. Both models qualitatively reproduce low-energy πN phenomenology and lead to nuclear matter saturation in the relativistic Hartree formalism, which includes baryon vacuum fluctuations. The pions propagator is evaluated in the one-nucleon-loop approximation, which corresponds to a relativistic random-phase approximation built on the Hartree ground state. Virtual NN-bar loops are included, and suitable renormalization techniques are illustrated. The local-density approximation is used to compare the threshold pion self-energy to the s-wave pion-nucleus optical potential. In the non-chiral model, s-wave pion-nucleus scattering is too large in both pseudoscalar and pseudovector calculations, indicating that additional constraints must be imposed on the Lagrangian. In the chiral model, the threshold self-energy vanishes automatically in the pseudovector case, but does so for pseudoscalar coupling only if the baryon effective mass is chosen self-consistently Since extrapolation from free space to nuclear density can lead to large effects, pion propagation in the medium can determine which πN coupling is more suitable for the relativistic nuclear many-body problem. Conversely, pion interactions constrain the model Lagrangian and the nuclear matter equation of state. An approximately chiral model with pseudovector coupling is favored

Relativistic three-particle dynamical equations: II. Application to the trinucleon system

International Nuclear Information System (INIS)

Adhikari, S.K.; Tomio, L.

1993-11-01

The contribution of relativistic dynamics on the neutron-deuteron scattering length and triton binding energy is calculated employing five sets tri nucleon potential models and four types of three-dimensional relativistic three-body equations suggested in the preceding paper. The relativistic correction to binding energy may vary a lot and even change sign depending on the relativistic formulation employed. The deviations of these observables from those obtained in nonrelativistic models follow the general universal trend of deviations introduced by off- and on-shell variations of two- and three-nucleon potentials in a nonrelativistic model calculation. Consequently, it will be difficult to separate unambiguously the effect of off-and on-shell variations of two and three-nucleon potentials on low-energy three-nucleon observables from the effect of relativistic dynamics. (author)

Nonlinear dynamic of interaction of the relativistic electron beam with plasma

International Nuclear Information System (INIS)

Dorofeenko, V.G.; Krasovitskii, V.B.; Osmolovsky, S.I.

1994-01-01

Quasi-transverse instability of thin relativistic electron beam in a dense plasma is studied numerically and analytically in a broad range of the frequency of the beam modulation and external longitudinal magnetic field. It is shown that the nonlinear stage of solution depends on the increment of the instability. It is permitted to classify possible nonlinear solutions and also to determine optimal regimes of the modulation for transport of beam along magnetic field in a plasma without substantial radial divergence. Numerical calculations show, that injection of the bunches with parameters, corresponding nonlinear regime of the beam's instability, in neutrally-charged plasma permits to output on the stationary regime without loss of particles

Fundamental relativistic rotator: Hessian singularity and the issue of the minimal interaction with electromagnetic field

Energy Technology Data Exchange (ETDEWEB)

Bratek, Lukasz, E-mail: lukasz.bratek@ifj.edu.pl [Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskego 152, PL-31342 Krakow (Poland)

2011-05-13

There are two relativistic rotators with Casimir invariants of the Poincare group being fixed parameters. The particular models of spinning particles were studied in the past both at the classical and quantum level. Recently, a minimal interaction with electromagnetic field has been considered. We show that the dynamical systems can be uniquely singled out from among other relativistic rotators by the unphysical requirement that the Hessian referring to the physical degrees of freedom should be singular. Closely related is the fact that the equations of free motion are not independent, making the evolution indeterminate. We show that the Hessian singularity cannot be removed by the minimal interaction with the electromagnetic field. By making use of a nontrivial Hessian null space, we show that a single constraint appears in the external field for consistency of the equations of motion with the Hessian singularity. The constraint imposes unphysical limitation on the initial conditions and admissible motions. We discuss the mechanism of appearance of unique solutions in external fields on an example of motion in the uniform magnetic field. We give a simple model to illustrate that similarly constrained evolution cannot be determinate in arbitrary fields.

Volume and surface photoemission from tungsten. I. Calculation of band structure and emission spectra

DEFF Research Database (Denmark)

Christensen, N. Egede; Feuerbacher, B.

1974-01-01

is obtained from an ad hoc potential based on a Dirac-Slater atomic calculation for the ground-state configuration and with full Slater exchange in the atomic as well as in the crystal potential. The selection of this best potential is justified by comparing the calculated band structure to Fermi...... of states. The present work includes a crude estimate of this surface density of states, which is derived from the bulk band structure by narrowing the d bands according to an effective number of neighbors per surface atom. Estimates of surface relaxation effects are also included.......The electronic energy-band structure of tungsten has been calculated by means of the relativistic-augmented-plane-wave method. A series of mutually related potentials are constructed by varying the electronic configuration and the amount of Slater exchange included. The best band structure...

On the design of experiments for the study of extreme field limits in the ultra-relativistic interaction of electromagnetic waves with plasmas

Science.gov (United States)

Bulanov, Sergei V.; Esirkepov, Timur Z.; Hayashi, Yukio; Kando, Masaki; Kiriyama, Hiromitsu; Koga, James K.; Kondo, Kiminori; Kotaki, Hideyuki; Pirozhkov, Alexander S.; Bulanov, Stepan S.; Zhidkov, Alexei G.; Chen, Pisin; Neely, David; Kato, Yoshiaki; Narozhny, Nikolay B.; Korn, Georg

2011-06-01

The critical electric field of quantum electrodynamics, called also the Schwinger field, is so strong that it produces electron-positron pairs from vacuum, converting the energy of light into matter. Since the dawn of quantum electrodynamics, there has been a dream on how to reach it on Earth. With the rise of laser technology this field has become feasible through the construction of extremely high power lasers or/and with the sophisticated use of nonlinear processes in relativistic plasmas. This is one of the most attractive motivations for extremely high power laser development, i.e. producing matter from vacuum by pure light in fundamental process of quantum electrodynamics in the nonperturbative regime. Recently it has been realized that a laser with intensity well below the Schwinger limit can create an avalanche of electron-positron pairs similar to a discharge before attaining the Schwinger field. It has also been realized that the Schwinger limit can be reached using an appropriate configuration of laser beams. In experiments on the collision of laser light and high intensity electromagnetic pulses generated by relativistic flying mirrors, with electron bunches produced by a conventional accelerator and with laser wake field accelerated electrons the studying of extreme field limits in the nonlinear interaction of electromagnetic waves is proposed. The regimes of dominant radiation reaction, which completely changes the electromagnetic wave-matter interaction, will be revealed. This will result in a new powerful source of high brightness gamma-rays. A possibility of the demonstration of the electronpositron pair creation in vacuum via multi-photon processes can be realized. This will allow modeling under terrestrial laboratory conditions neutron star magnetospheres, cosmological gamma ray bursts and the Leptonic Era of the Universe.

Dynamics of the relativistic acceleration of charged particles in space plasma while surfing the package electromagnetic waves

International Nuclear Information System (INIS)

Erokhin, N.S.; Zol'nikova, N.N.; Kuznetsov, E.A.; Mikhajlovskaya, L.A.

2010-01-01

Based on numerical calculations considered the relativistic acceleration of charged particles in space plasma when surfing on the spatially localized package of electromagnetic waves. The problem is reduced to the study of unsteady, nonlinear equation for the wave phase at the carrier frequency at the location of the accelerated charge, which is solved numerically. We study the temporal dynamics of the relativistic factor, the component of momentum and velocity of the particle, its trajectory is given gyro-rotation in an external magnetic field after the departure of the effective potential well. Dependence of the dynamics of a particle interacting with the wave of the sign of the velocity of the charge along the wave front. We formulate the optimal conditions of the relativistic particle acceleration wave packet, indicate the possibility of again (after a number gyro-turnover) charge trapping wave with an additional relativistic acceleration.

One- and two-center ETF-integrals of first order in relativistic calculation of NMR parameters

Science.gov (United States)

Slevinsky, R. M.; Temga, T.; Mouattamid, M.; Safouhi, H.

2010-06-01

The present work focuses on the analytical and numerical developments of first-order integrals involved in the relativistic calculation of the shielding tensor using exponential-type functions as a basis set of atomic orbitals. For the analytical development, we use the Fourier integral transformation and practical properties of spherical harmonics and the Rayleigh expansion of the plane wavefunctions. The Fourier transforms of the operators were derived in previous work and they are used for analytical development. In both the one- and two-center integrals, Cauchy's residue theorem is used in the final developments of the analytical expressions, which are shown to be accurate to machine precision.

One- and two-center ETF-integrals of first order in relativistic calculation of NMR parameters

Energy Technology Data Exchange (ETDEWEB)

Slevinsky, R M; Temga, T; Mouattamid, M; Safouhi, H, E-mail: hassan.safouhi@ualberta.c [Mathematical Section, Campus Saint-Jean, University of Alberta, 8406, 91 Street, Edmonton, Alberta T6C 4G9 (Canada)

2010-06-04

The present work focuses on the analytical and numerical developments of first-order integrals involved in the relativistic calculation of the shielding tensor using exponential-type functions as a basis set of atomic orbitals. For the analytical development, we use the Fourier integral transformation and practical properties of spherical harmonics and the Rayleigh expansion of the plane wavefunctions. The Fourier transforms of the operators were derived in previous work and they are used for analytical development. In both the one- and two-center integrals, Cauchy's residue theorem is used in the final developments of the analytical expressions, which are shown to be accurate to machine precision.

Studies of Ionic Photoionization Using Relativistic Random Phase Approximation and Relativistic Multichannel Quantum Defect Theory

Science.gov (United States)

Haque, Ghousia Nasreen

The absorption of electromagnetic radiation by positive ions is one of the fundamental processes of nature which occurs in every intensely hot environment. Due to the difficulties in producing sufficient densities of ions in a laboratory, there are very few measurements of ionic photoabsorption parameters. On the theoretical side, some calculations have been made of a few major photoionization parameters, but generally speaking, most of the work done so far has employed rather simple single particle models and any theoretical work which has adequately taken into account intricate atomic many-body and relativistic effects is only scanty. In the present work, several complex aspects of atomic/ionic photoabsorption parameters have been studied. Non -resonant photoionization in neon and argon isonuclear as well as isoelectronic sequences has been studied using a very sophisticated technique, namely the relativistic random phase approximation (RRPA). This technique takes into account relativistic effects as well as an important class of major many-body effects on the same footing. The present calculations confirmed that gross features of photoionization parameters calculated using simpler models were not an artifact of the simple model. Also, the present RRPA calculations on K^+ ion and neutral Ar brought out the relative importance of various many-body effects such the inter-channel coupling. Inter-channel coupling between discrete bound state photoexcitation channels from an inner atomic/ionic level and photoionization continuum channels from an outer atomic/ionic level leads to the phenomena of autoionization resonances in the photoionization process. These resonances lead to very complex effects in the atomic/ionic photoabsorption spectra. These resonances have been calculated and studied in the present work in the neon and magnesium isoelectronic sequences using the relativistic multi-channel quantum defect theory (RMQDT) within the framework of the RRPA. The

Fast-electron-relaxation measurement for laser-solid interaction at relativistic laser intensities

International Nuclear Information System (INIS)

Chen, H.; Shepherd, R.; Chung, H. K.; Kemp, A.; Hansen, S. B.; Wilks, S. C.; Ping, Y.; Widmann, K.; Fournier, K. B.; Beiersdorfer, P.; Dyer, G.; Faenov, A.; Pikuz, T.

2007-01-01

We present measurements of the fast-electron-relaxation time in short-pulse (0.5 ps) laser-solid interactions for laser intensities of 10 17 , 10 18 , and 10 19 W/cm 2 , using a picosecond time-resolved x-ray spectrometer and a time-integrated electron spectrometer. We find that the laser coupling to hot electrons increases as the laser intensity becomes relativistic, and that the thermalization of fast electrons occurs over time scales on the order of 10 ps at all laser intensities. The experimental data are analyzed using a combination of models that include Kα generation, collisional coupling, and plasma expansion

Configuration mixing calculations with basis states obtained from constrained variational methods

International Nuclear Information System (INIS)

Miller, H.G.; Schroeder, H.P.

1982-01-01

Configuration mixing calculations have been performed in 20 Ne using basis states which are energetically the lowest-lying solutions of the constrained Hartree-Fock equations with an angular momentum constraint of the form 2 > = J(J + 1), For J = 6, very good agreement with the lower-lying 6 + states in an exact eigenvalue spectrum has been obtained with relatively few PAV-K mixed CHF basis states. (orig.)

Configuration interaction effect on open M shell Fe and Ni LTE spectral opacities, Rosseland and Planck means

International Nuclear Information System (INIS)

Gilles, D; Busquet, M; Gilleron, F; Pain, J-C; Klapisch, M

2016-01-01

We have recently shown that iron and nickel open M-shell opacity spectra, up to Δn = 2 are very sensitive to Configuration Interaction (CI) treatments at temperature around 15 eV and for various densities. To do so we had compared extensive CI calculations obtained with two opacity codes HULLAC-v9 and SCO-RCG. In this work we extend these comparisons to a first evaluation of CI effects on Rosseland and Planck means. (paper)

Approximate relativistic corrections to atomic radial wave functions

International Nuclear Information System (INIS)

Cowan, R.D.; Griffin, D.C.

1976-01-01

The mass-velocity and Darwin terms of the one-electron-atom Pauli equation have been added to the Hartree-Fock differential equations by using the HX formula to calculate a local central field potential for use in these terms. Introduction of the quantum number j is avoided by omitting the spin-orbit term of the Pauli equation. The major relativistic effects, both direct and indirect, are thereby incorporated into the wave functions, while allowing retention of the commonly used nonrelativistic formulation of energy level calculations. The improvement afforded in calculated total binding energies, excitation energies, spin-orbit parameters, and expectation values of r/sub m/ is comparable with that provided by fully relativistic Dirac-Hartree-Fock calculations

Photochemistry of ethylene: A multireference configuration interaction investigation of the excited-state energy surfaces

International Nuclear Information System (INIS)

Barbatti, M.; Paier, J.; Lischka, H.

2004-01-01

Multireference configuration interaction with singles and doubles (MR-CISD) calculations have been performed for the optimization of conical intersections and stationary points on the ethylene excited-state energy surfaces using recently developed methods for the computation of analytic gradients and nonadiabatic coupling terms. Basis set dependence and the effect of various choices of reference spaces for the MR-CISD calculations have been investigated. The crossing seam between the S 0 and S 1 states has been explored in detail. This seam connects all conical intersections presently known for ethylene. Major emphasis has been laid on the hydrogen-migration path. Starting in the V state of twisted-orthogonal ethylene, a barrierless path to ethylidene was found. The feasibility of ethylidene formation will be important for the explanation of the relative yield of cis and trans H 2 elimination

Non-relativistic Limit of a Dirac Polaron in Relativistic Quantum Electrodynamics

CERN Document Server

Arai, A

2006-01-01

A quantum system of a Dirac particle interacting with the quantum radiation field is considered in the case where no external potentials exist. Then the total momentum of the system is conserved and the total Hamiltonian is unitarily equivalent to the direct integral $\\int_{{\\bf R}^3}^\\oplus\\overline{H({\\bf p})}d{\\bf p}$ of a family of self-adjoint operators $\\overline{H({\\bf p})}$ acting in the Hilbert space $\\oplus^4{\\cal F}_{\\rm rad}$, where ${\\cal F}_{\\rm rad}$ is the Hilbert space of the quantum radiation field. The fibre operator $\\overline{H({\\bf p})}$ is called the Hamiltonian of the Dirac polaron with total momentum ${\\bf p} \\in {\\bf R}^3$. The main result of this paper is concerned with the non-relativistic (scaling) limit of $\\overline{H({\\bf p})}$. It is proven that the non-relativistic limit of $\\overline{H({\\bf p})}$ yields a self-adjoint extension of a Hamiltonian of a polaron with spin $1/2$ in non-relativistic quantum electrodynamics.

Spectral analysis of the 4d96s configuration in eight times ionized xenon, Xe IX

International Nuclear Information System (INIS)

Raineri, M.; Gallardo, M.; Reyna Almandos, J.G.

2006-01-01

A capillary light source was used to observe the spectrum of eight times ionized xenon, Xe IX, in the vacuum ultraviolet range, 270-2000 A. Sixteen transitions have been identified as combinations between energy levels of the 4d 9 6s with 4d 9 5p configuration, and all 4d 9 6s levels have been determined. The present analysis is based on an accurate extrapolation of energy parameters and experimental energy level values in the Pd I isoelectronic sequence. The energy parameters were obtained with Hartree-Fock relativistic calculations. Least-squares parametric calculation has been carried out to study the fit between experimental and theoretical values

Conductivity of a relativistic plasma

Energy Technology Data Exchange (ETDEWEB)

Braams, B.J.; Karney, C.F.F.

1989-03-01

The collision operator for a relativistic plasma is reformulated in terms of an expansion in spherical harmonics. This formulation is used to calculate the electrical conductivity. 13 refs., 1 fig., 1 tab.

Conductivity of a relativistic plasma

International Nuclear Information System (INIS)

Braams, B.J.; Karney, C.F.F.

1989-03-01

The collision operator for a relativistic plasma is reformulated in terms of an expansion in spherical harmonics. This formulation is used to calculate the electrical conductivity. 13 refs., 1 fig., 1 tab

SOLAR MIXTURE OPACITY CALCULATIONS USING DETAILED CONFIGURATION AND LEVEL ACCOUNTING TREATMENTS

International Nuclear Information System (INIS)

Blancard, Christophe; Cossé, Philippe; Faussurier, Gérald

2012-01-01

An opacity model (OPAS) combining detailed configuration and level accounting treatments has been developed to calculate radiative opacity of plasmas in local thermodynamic equilibrium. The model is presented and used to compute spectral opacities of a solar mixture. Various density-temperature couples have been considered from the solar center up to the vicinity of the radiative/convective zone interface. For a given solar thermodynamic path, OPAS calculations are compared to Opacity Project (OP) and OPAL data. Rosseland mean opacity values are in very good agreement over all the considered solar thermodynamic path, while OPAS and OP spectral opacities of each element may vary considerably. Main sources of discrepancy are discussed.

Surface incompressibility from semiclassical relativistic mean field calculations

International Nuclear Information System (INIS)

Patra, S.K.; Centelles, M.; Vinas, X.; Estal, M. del

2002-01-01

By using the scaling method and the Thomas-Fermi and extended Thomas-Fermi approaches to relativistic mean field theory the surface contribution to the leptodermous expansion of the finite nuclei incompressibility K A has been self-consistently computed. The validity of the simplest expansion, which contains volume, volume-symmetry, surface, and Coulomb terms, is examined by comparing it with self-consistent results of K A for some currently used nonlinear σ-ω parameter sets. A numerical estimate of higher-order contributions to the leptodermous expansion, namely, the curvature and surface-symmetry terms, is made

Relativistic three-body model of pion-deuton elasic scattering

International Nuclear Information System (INIS)

Giraud, Noel.

1978-01-01

The Aaron-Amado-Young equations for the relativistic three-body problem are derived following the Blauckenbecker - Sugar method. The angular momentum reduction is carried out using suitable relative momenta. The pion-deuteron elastic scattering is calculated using the equations in which relativistic kinematics are retained only for the pion. After a general study of the observables in the energy range 25 to 256 MeV, detailed calculations are performed at 142 MeV [fr

Electronic structure of molecules using relativistic effective core potentials

International Nuclear Information System (INIS)

Hay, P.J.

1981-01-01

Starting with one-component Cowan-Griffin relativistic Hartree-Fock orbitals, which successfully incorporate the mass-velocity and Darwin terms present in more complicated wavefunctions such as Dirac-Hartree-Fock, one can derive relativistic effective core potentials (RECP's) to carry out molecular calculations. These potentials implicitly include the dominant relativistic terms for molecules while allowing one to use the traditional quantum chemical techniques for studying the electronic structure of molecules. The effects of spin-orbit coupling can then be included using orbitals from such calculations using an effective 1-electron, 1-center spin-orbit operator. Applications to molecular systems involving heavy atoms, show good agreement with available spectroscopic data on molecular geometries and excitation energies

Calculation of ion storage in electron beams with account of ion-ion interactions

International Nuclear Information System (INIS)

Perel'shtejn, Eh.A.; Shirkov, G.D.

1979-01-01

Ion storage in relativistic electron beams was calculated taking account of ion-ion charge exchange and ionization. The calculations were made for nitrogen ion storage from residual gas during the compression of electron rings in the adhezator of the JINR heavy ion accelerator. The calculations were made for rings of various parameters and for various pressures of the residual gas. The results are compared with analogous calculations made without account of ion-ion processes. It is shown that at heavy loading of a ring by ions ion-ion collisions play a significant part, and they should be taken into account while calculating ion storage

Precursor Wave Emission Enhanced by Weibel Instability in Relativistic Shocks

Science.gov (United States)

Iwamoto, Masanori; Amano, Takanobu; Hoshino, Masahiro; Matsumoto, Yosuke

2018-05-01

We investigated the precursor wave emission efficiency in magnetized purely perpendicular relativistic shocks in pair plasmas. We extended our previous study to include the dependence of upstream magnetic field orientations. We performed two-dimensional particle-in-cell simulations and focused on two magnetic field orientations: the magnetic field in the simulation plane (i.e., in-plane configuration) and that perpendicular to the simulation plane (i.e., out-of-plane configuration). Our simulations in the in-plane configuration demonstrated that not only extraordinary but also ordinary mode waves are excited. We quantified the emission efficiency as a function of the magnetization parameter σ e and found that the large-amplitude precursor waves are emitted for a wide range of σ e . We found that especially at low σ e , the magnetic field generated by Weibel instability amplifies the ordinary mode wave power. The amplitude is large enough to perturb the upstream plasma, and transverse density filaments are generated as in the case of the out-of-plane configuration investigated in the previous study. We confirmed that our previous conclusion holds regardless of upstream magnetic field orientations with respect to the two-dimensional simulation plane. We discuss the precursor wave emission in three dimensions and the feasibility of wakefield acceleration in relativistic shocks based on our results.

Relativistic four-component multiconfigurational self-consistent-field theory for molecules

DEFF Research Database (Denmark)

Jensen, Hans Jørgen Aa; Dyall, Kenneth G.; Saue, Trond

1996-01-01

A formalism for relativistic four-component multiconfigurational self-consistent-field calculations on molecules is presented. The formalism parallels a direct second-order restricted-step algorithm developed for nonrelativistic molecular calculations. The presentation here focuses on the differe......A formalism for relativistic four-component multiconfigurational self-consistent-field calculations on molecules is presented. The formalism parallels a direct second-order restricted-step algorithm developed for nonrelativistic molecular calculations. The presentation here focuses...... the memory used by the largest nonrelativistic calculation in the equivalent basis, due to the complex arithmetic. The feasibility of the calculations is then determined more by the disk space for storage of integrals and N-particle expansion vectors....

Characteristics of the interactions of {sup 12} C, {sup 22} Ne and {sup 28} Si with emulsion nuclei accompanied with relativistic hadrons in the backward hemisphere at Dubna energy. Vol. 2

Energy Technology Data Exchange (ETDEWEB)

El-Nadi, N; Abdel-salam, A [Department of Physics, Faculty of Sciences, Cairo University, Cairo (Egypt); Mossa, N A [Basic science Department, Faculty of Engineering-Shoubra, Zagazig University, Cairo (Egypt); Krasnov, S A [Jinr, Dubna, (Russian Federation)

1996-03-01

A detailed study of the characteristics of the interactions accompanied by relativistic hadrons in the backward hemisphere in the collisions of {sup 12} C, {sup 22} Ne and {sup 26} Si projectiles with emulsion nuclei at incident momentum in the range (4.1-4.5) a GeV/C was carried out. For this purpose, random samples of 819, 3812, and 1209 events in case of {sup 22} C, {sup 22} Ne and {sup 26} Si interactions are analyzed, respectively. The behaviour of the shower particles multiplicities, and the pseudorapidity distributions for the different interactions were investigated in terms of the number of emitted shower particles. The pseudorapidity distribution of the shower particles from the interactions accompanied by the emission of backward relativistic hadrons are found to be satisfactorily fitted by a single spindle Gaussian distribution. On the other hand, the pseudorapidity for the shower particles emitted in the interactions not accompanied by backward relativistic hadron are fitted by two Gaussian distributions with two distinct average values. The dispersion of the pseudorapidity distributions are insensitive to the number of the backward relativistic hadrons n{sup b}{sub s}. However, the average pseudorapidity decreases with increase of number of backward relativistic hadrons. The dependence of the average number of the shower particles produced in the backward and forward hemispheres on the projectile mass number and the impact parameter are also presented. The results yield quite interesting information regarding the production of such backward relativistic hadrons in heavy ions interactions. 9 figs., 3 tabs.

VENUS+δf - A bootstrap current calculation module for 3D configurations

International Nuclear Information System (INIS)

Isaev, M.Yu.; Brunner, S.; Cooper, W.A.; Tran, T.M.; Bergmann, A.; Beidler, C.D.; Geiger, J.; Maassberg, H.; Nuehrenberg, J.; Schmidt, M.

2005-01-01

We present a new 3D code VENUS+δf for neoclassical transport calculations in nonaxisymmetric toroidal systems. Numerical drift orbits from the original VENUS code and the δf method for tokamak transport calculations are combined. The first results obtained with VENUS+δf are compared with neoclassical theory for different collisional regimes in a JT-60 tokamak test case with monoenergetic particles and with a Maxwellian distribution. Benchmarks with DKES code results for the bootstrap current in the W7X configuration as well as further VENUS+δf developments are discussed. (author)

Holographic Aspects of a Relativistic Nonconformal Theory

Directory of Open Access Journals (Sweden)

Chanyong Park

2013-01-01

Full Text Available We study a general D-dimensional Schwarzschild-type black brane solution of the Einstein-dilaton theory and derive, by using the holographic renormalization, its thermodynamics consistent with the geometric results. Using the membrane paradigm, we calculate the several hydrodynamic transport coefficients and compare them with the results obtained by the Kubo formula, which shows the self-consistency of the gauge/gravity duality in the relativistic nonconformal theory. In order to understand more about the relativistic non-conformal theory, we further investigate the binding energy, drag force, and holographic entanglement entropy of the relativistic non-conformal theory.

Three-dimensional formulation of the relativistic two-body problem in terms of rapidities

International Nuclear Information System (INIS)

Amirkhanov, I.V.; Grusha, G.V.; Mir-Kasimov, R.M.

1976-01-01

The scheme, based on the three-dimensional relativistic equation of the quasi-potential type is developed. As a basic variable rapidity, canonically conjugated to the relativistic relative distance is adopted. The free Green function has a simple pole in the complex rapidity plane, ensuring the fulfillment of the elastic unitarity for real potentials. In the local potential case the corresponding partial wave equation in configurational r-representation is a differential second-order equation. The problem of boundary conditions, which is a non-trivial one in the relativistic r-space, is studied. The exact solutions of the equation in simple cases have been found

A deterministic alternative to the full configuration interaction quantum Monte Carlo method

Energy Technology Data Exchange (ETDEWEB)

Tubman, Norm M.; Lee, Joonho; Takeshita, Tyler Y.; Head-Gordon, Martin; Whaley, K. Birgitta [University of California, Berkeley, Berkeley, California 94720 (United States)

2016-07-28

Development of exponentially scaling methods has seen great progress in tackling larger systems than previously thought possible. One such technique, full configuration interaction quantum Monte Carlo, is a useful algorithm that allows exact diagonalization through stochastically sampling determinants. The method derives its utility from the information in the matrix elements of the Hamiltonian, along with a stochastic projected wave function, to find the important parts of Hilbert space. However, the stochastic representation of the wave function is not required to search Hilbert space efficiently, and here we describe a highly efficient deterministic method that can achieve chemical accuracy for a wide range of systems, including the difficult Cr{sub 2} molecule. We demonstrate for systems like Cr{sub 2} that such calculations can be performed in just a few cpu hours which makes it one of the most efficient and accurate methods that can attain chemical accuracy for strongly correlated systems. In addition our method also allows efficient calculation of excited state energies, which we illustrate with benchmark results for the excited states of C{sub 2}.

Multireference configuration interaction treatment of potential energy surfaces: symmetric dissociation of H/sub 2/O in a double-zeta basis

Energy Technology Data Exchange (ETDEWEB)

Brown, F B; Shavitt, I; Shepard, R

1984-03-23

Multiconfiguration self-consistent fields (SCF) and multireference configurational interaction (CI) calculations have been performed for the H/sub 2/O molecule in a double-zeta basis for four symmetric geometries, for comparison with full CI results. Unlike single-reference results, the energy errors are almost independent of geometry, allowing unbiased treatments of potential energy surfaces. 35 references, 1 figure, 2 tables.

Relativistic scattering theory of charged spinless particles

International Nuclear Information System (INIS)

Alt, E.O.; Hannemann, M.

1986-01-01

In the context of relativistic quantum mechanics the scattering is discussed of two and three charged spinless particles. The corresponding transition operators are shown to satisfy four-dimensional Lippmann-Schwinger and eight-dimensional Faddeev-type equations, respectively. A simplified model of two particles with Coulomb interaction can be solved exactly. Calculations have been made of (i) the partial wave S-matrix from which the bound state spectrum has been extracted; the latter agrees with a fourth-order result of Schwinger; (ii) the full scattering amplitude which in the weak-field limit coincides with the expression derived by Fried et al. from eikonalized QED. (author)

Matter Formed at the BNL Relativistic Heavy Ion Collider

International Nuclear Information System (INIS)

Brown, G.E.; Gelman, B.A.; Rho, Mannque

2006-01-01

We suggest that the 'new form of matter' found just above T c by the Relativistic Heavy Ion Collider is made up of tightly bound quark-antiquark pairs, essentially 32 chirally restored (more precisely, nearly massless) mesons of the quantum numbers of π, σ, ρ, and a 1 . Taking the results of lattice gauge simulations (LGS) for the color Coulomb potential from the work of the Bielefeld group and feeding this into a relativistic two-body code, after modifying the heavy-quark lattice results so as to include the velocity-velocity interaction, all ground-state eigenvalues of the 32 mesons go to zero at T c just as they do from below T c as predicted by the vector manifestation of hidden local symmetry. This could explain the rapid rise in entropy up to T c found in LGS calculations. We argue that how the dynamics work can be understood from the behavior of the hard and soft glue

Relativistic Gas Drag on Dust Grains and Implications

Energy Technology Data Exchange (ETDEWEB)

Hoang, Thiem, E-mail: thiemhoang@kasi.re.kr [Korea Astronomy and Space Science Institute, Daejeon 34055 (Korea, Republic of); Korea University of Science and Technology, Daejeon, 34113 (Korea, Republic of)

2017-09-20

We study the drag force on grains moving at relativistic velocities through interstellar gas and explore its application. First, we derive a new analytical formula of the drag force at high energies and find that it is significantly reduced compared to the classical model. Second, we apply the obtained drag force to calculate the terminal velocities of interstellar grains by strong radiation sources such as supernovae and active galactic nuclei (AGNs). We find that grains can be accelerated to relativistic velocities by very luminous AGNs. We then quantify the deceleration of relativistic spacecraft proposed by the Breakthrough Starshot initiative due to gas drag on a relativistic lightsail. We find that the spacecraft’s decrease in speed is negligible because of the suppression of gas drag at relativistic velocities, suggesting that the lightsail may be open for communication during its journey to α Centauri without causing a considerable delay. Finally, we show that the damage to relativistic thin lightsails by interstellar dust is a minor effect.

Pierce-type dispersion relation for an intense relativistic electron beam interacting with a slow-wave structure

International Nuclear Information System (INIS)

Chen, C.

1994-01-01

A Pierce-type dispersion relation is derived for the interaction of an intense relativistic electron beam with a cylindrical slow-wave structure of arbitrary corrugation depth. It is shown that near a resonance, the Pierce parameter can be expressed in terms of the vacuum dispersion function and the beam current. The dispersion relation is valid in both the low-current (Compton) regime and the high-current (Raman) regime. The dispersion characteristics of the interaction, such as the linear instability growth rate and bandwidth, are analyzed for both regimes

Symmetric low-voltage powering system for relativistic electronic devices

International Nuclear Information System (INIS)

Agafonov, A.V.; Lebedev, A.N.; Krastelev, E.G.

2005-01-01

A special driver for double-sided powering of relativistic magnetrons and several methods of localized electron flow forming in the interaction region of relativistic magnetrons are proposed and discussed. Two experimental installations are presented and discussed. One of them is designed for laboratory research and demonstration experiments at a rather low voltage. The other one is a prototype of a full-scale installation for an experimental research at relativistic levels of voltages on the microwave generation in the new integrated system consisting of a relativistic magnetron and symmetrical induction driver

Configuration mixing in the sdg interacting boson model

International Nuclear Information System (INIS)

Bouldjedri, A; Van Isacker, P; Zerguine, S

2005-01-01

A wavefunction analysis of the strong-coupling limits of the sdg interacting boson model is presented. The analysis is carried out for two-boson states and allows us to characterize the boson configuration mixing in the different limits. Based on these results and those of a shell-model analysis of the sdg IBM, qualitative conclusions are drawn about the range of applicability of each limit

Configuration mixing in the sdg interacting boson model

Energy Technology Data Exchange (ETDEWEB)

Bouldjedri, A [Department of Physics, Faculty of Science, University of Batna, Avenue Boukhelouf M El Hadi, 05000 Batna (Algeria); Van Isacker, P [GANIL, BP 55027, F-14076 Caen cedex 5 (France); Zerguine, S [Department of Physics, Faculty of Science, University of Batna, Avenue Boukhelouf M El Hadi, 05000 Batna (Algeria)

2005-11-01

A wavefunction analysis of the strong-coupling limits of the sdg interacting boson model is presented. The analysis is carried out for two-boson states and allows us to characterize the boson configuration mixing in the different limits. Based on these results and those of a shell-model analysis of the sdg IBM, qualitative conclusions are drawn about the range of applicability of each limit.

Effect of phase transition on QGP fluid in ultra-relativistic heavy ion collision

International Nuclear Information System (INIS)

Nonaka, Chiho; Miyamura, Osamu; Muroya, Shin

2001-01-01

A full (3+1)-dimensional calculation using the Lagrangian hydrodynamics is proposed for relativistic nuclear collisions. The calculation enables us to evaluate anisotropic flow of hot and dense matter which appears in non-central and/or asymmetrical relativistic nuclear collisions. The relativistic hydrodynamical model is related to the equation of the state and the useful for the verification of quark-gluon plasma state. By virtue of the Lagrangian hydrodynamics we can easily trace the trajectory which corresponds to the adiabatic paths in the T-μ plane. We evaluate the directly of the influence of the phase transition to physical phenomena in the ultra-relativistic nuclear collisions. Using our relativistic hydrodynamical model, we discuss the effect of the phase transition on the collective flow. (author)

CI+MBPT calculations of Ar I energies, g factors, and transition line strengths

Science.gov (United States)

Savukov, I. M.

2018-03-01

Excited states of noble gas atoms present certain challenges to atomic theory for several reasons: first, relativistic effects are important and LS coupling is not optimal; second, energy intervals can be quite small, leading to strong mixing of states; third, many-body perturbation theory for hole states does not converge well. Previously, some attempts were made to solve this problem, using for example the all-order coupled-cluster approach and particle-hole configuration-interaction many-body perturbation theory (CI-MBPT) with modified denominators. However, while these approaches were promising, the accuracy was still limited. In this paper, we calculate Ar I energies, g factors, and transition amplitudes using ab initio CI-MBPT with eight valence electrons to avoid the problem of slow convergence of MBPT due to strong interaction between 3p and 3s states. We also included in CI many dominant states obtained by double excitations of the ground state configuration. Thus perturbation corrections were needed only for 1s, 2s, 2p core electrons non-included in valence-valence CI, which are quite small. We found that energy, g factors, and electric dipole matrix elements are in reasonable agreement with experiments. It is noteworthy that the theory agreed well with accurately measured g factors. Experimental oscillator strengths have large uncertainty, so in some cases we made a comparison with average values.

Relativistic nonlinear electrodynamics the QED vacuum and matter in super-strong radiation fields

CERN Document Server

Avetissian, Hamlet K

2016-01-01

This revised edition of the author’s classic 2006 text offers a comprehensively updated review of the field of relativistic nonlinear electrodynamics. It explores the interaction of strong and super-strong electromagnetic/laser radiation with the electromagnetic quantum vacuum and diverse types of matter – including free charged particles and antiparticles, acceleration beams, plasma and plasmous media.  The appearance of laser sources of relativistic and ultra-relativistic intensities over the last decade has stimulated investigation of a large class of processes under such super-strong radiation fields. Revisions for this second edition reflect these developments and the book includes new chapters on Bremsstrahlung and nonlinear absorption of superintense radiation in plasmas, the nonlinear interaction of relativistic atoms with intense laser radiation, nonlinear interaction of strong laser radiation with Graphene, and relativistic nonlinear phenomena in solid-plasma targets under supershort laser pul...

An excited-state approach within full configuration interaction quantum Monte Carlo

International Nuclear Information System (INIS)

Blunt, N. S.; Smart, Simon D.; Booth, George H.; Alavi, Ali

2015-01-01

We present a new approach to calculate excited states with the full configuration interaction quantum Monte Carlo (FCIQMC) method. The approach uses a Gram-Schmidt procedure, instantaneously applied to the stochastically evolving distributions of walkers, to orthogonalize higher energy states against lower energy ones. It can thus be used to study several of the lowest-energy states of a system within the same symmetry. This additional step is particularly simple and computationally inexpensive, requiring only a small change to the underlying FCIQMC algorithm. No trial wave functions or partitioning of the space is needed. The approach should allow excited states to be studied for systems similar to those accessible to the ground-state method due to a comparable computational cost. As a first application, we consider the carbon dimer in basis sets up to quadruple-zeta quality and compare to existing results where available

Magnetic anisotropy of heteronuclear dimers in the gas phase and supported on graphene: relativistic density-functional calculations.

Science.gov (United States)

Błoński, Piotr; Hafner, Jürgen

2014-04-09

The structural and magnetic properties of mixed PtCo, PtFe, and IrCo dimers in the gas phase and supported on a free-standing graphene layer have been calculated using density-functional theory, both in the scalar-relativistic limit and self-consistently including spin-orbit coupling. The influence of the strong magnetic moments of the 3d atoms on the spin and orbital moments of the 5d atoms, and the influence of the strong spin-orbit coupling contributed by the 5d atom on the orbital moments of the 3d atoms have been studied in detail. The magnetic anisotropy energy is found to depend very sensitively on the nature of the eigenstates in the vicinity of the Fermi level, as determined by band filling, exchange splitting and spin-orbit coupling. The large magnetic anisotropy energy of free PtCo and IrCo dimers relative to the easy direction parallel to the dimer axis is coupled to a strong anisotropy of the orbital magnetic moments of the Co atom for both dimers, and also on the Ir atom in IrCo. In contrast the PtFe dimer shows a weak perpendicular anisotropy and only small spin and orbital anisotropies of opposite sign on the two atoms. For dimers supported on graphene, the strong binding within the dimer and the stronger interaction of the 3d atom with the substrate stabilizes an upright geometry. Spin and orbital moments on the 3d atom are strongly quenched, but due to the weaker binding within the dimer the properties of the 5d atom are more free-atom-like with increased spin and orbital moments. The changes in the magnetic moment are reflected in the structure of the electronic eigenstates near the Fermi level, for all three dimers the easy magnetic direction is now parallel to the dimer axis and perpendicular to the graphene layer. The already very large magnetic anisotropy energy (MAE) of IrCo is further enhanced by the interaction with the support, the MAE of PtFe changes sign, and that of the PtCo dimer is reduced. These changes are discussed in relation to

Electron-deuteron scattering in a relativistic theory of hadrons

International Nuclear Information System (INIS)

Phillips, D.

1998-11-01

The author reviews a three-dimensional formalism that provides a systematic way to include relativistic effects including relativistic kinematics, the effects of negative-energy states, and the boosts of the two-body system in calculations of two-body bound-states. He then explains how to construct a conserved current within this relativistic three-dimensional approach. This general theoretical framework is specifically applied to electron-deuteron scattering both in impulse approximation and when the ρπγ meson-exchange current is included. The experimentally-measured quantities A, B, and T 20 are calculated over the kinematic range that is probed in Jefferson Lab experiments. The role of both negative-energy states and meson retardation appears to be small in the region of interest

Energies and E1, M1, E2, and M2 transition rates for states of the 2s{sup 2}2p{sup 3}, 2s2p{sup 4}, and 2p{sup 5} configurations in nitrogen-like ions between F III and Kr XXX

Energy Technology Data Exchange (ETDEWEB)

Rynkun, P., E-mail: pavel.rynkun@gmail.com [Department of Physics and Information Technologies, Lithuanian University of Educational Science, Studentu 39, LT-08106 Vilnius (Lithuania); Jönsson, P. [Group for Materials Science and Applied Mathematics, Malmö University, 20506 Malmö (Sweden); Gaigalas, G. [Department of Physics and Information Technologies, Lithuanian University of Educational Science, Studentu 39, LT-08106 Vilnius (Lithuania); Vilnius University, Institute of Theoretical Physics and Astronomy, A. Goštauto 12, LT-01108 Vilnius (Lithuania); Froese Fischer, C. [National Institute of Standards and Technology, Gaithersburg, MD 20899-8420 (United States)

2014-03-15

Based on relativistic wavefunctions from multiconfiguration Dirac–Hartree–Fock and configuration interaction calculations, E1, M1, E2, and M2 transition rates, weighted oscillator strengths, and lifetimes are evaluated for the states of the (1s{sup 2})2s{sup 2}2p{sup 3},2s2p{sup 4}, and 2p{sup 5} configurations in all nitrogen-like ions between F III and Kr XXX. The wavefunction expansions include valence, core–valence, and core–core correlation effects through single–double multireference expansions to increasing sets of active orbitals. The computed energies agree very well with experimental values, with differences of only 300–600 cm{sup −1} for the majority of the levels and ions in the sequence. Computed transitions rates are in close agreement with available data from MCHF-BP calculations by Tachiev and Froese Fischer [G.I. Tachiev, C. Froese Fischer, A and A 385 (2002) 716].

Effects of adiabatic, relativistic, and quantum electrodynamics interactions on the pair potential and thermophysical properties of helium.

Science.gov (United States)

Cencek, Wojciech; Przybytek, Michał; Komasa, Jacek; Mehl, James B; Jeziorski, Bogumił; Szalewicz, Krzysztof

2012-06-14

The adiabatic, relativistic, and quantum electrodynamics (QED) contributions to the pair potential of helium were computed, fitted separately, and applied, together with the nonrelativistic Born-Oppenheimer (BO) potential, in calculations of thermophysical properties of helium and of the properties of the helium dimer. An analysis of the convergence patterns of the calculations with increasing basis set sizes allowed us to estimate the uncertainties of the total interaction energy to be below 50 ppm for interatomic separations R smaller than 4 bohrs and for the distance R = 5.6 bohrs. For other separations, the relative uncertainties are up to an order of magnitude larger (and obviously still larger near R = 4.8 bohrs where the potential crosses zero) and are dominated by the uncertainties of the nonrelativistic BO component. These estimates also include the contributions from the neglected relativistic and QED terms proportional to the fourth and higher powers of the fine-structure constant α. To obtain such high accuracy, it was necessary to employ explicitly correlated Gaussian expansions containing up to 2400 terms for smaller R (all R in the case of a QED component) and optimized orbital bases up to the cardinal number X = 7 for larger R. Near-exact asymptotic constants were used to describe the large-R behavior of all components. The fitted potential, exhibiting the minimum of -10.996 ± 0.004 K at R = 5.608 0 ± 0.000 1 bohr, was used to determine properties of the very weakly bound (4)He(2) dimer and thermophysical properties of gaseous helium. It is shown that the Casimir-Polder retardation effect, increasing the dimer size by about 2 Å relative to the nonrelativistic BO value, is almost completely accounted for by the inclusion of the Breit-interaction and the Araki-Sucher contributions to the potential, of the order α(2) and α(3), respectively. The remaining retardation effect, of the order of α(4) and higher, is practically negligible for the bound

Self-consistent relativistic QRPA studies of soft modes and spin-isospin resonances in unstable nuclei

International Nuclear Information System (INIS)

Paar, N.; Niksic, T.; Marketin, T.; Vretenar, D.; Ring, P.

2005-01-01

The excitation phenomena in unstable nuclei are investigated in the framework of the relativistic quasiparticle random-phase approximation (RQRPA) in the relativistic Hartree-Bogolyubov model (RHB) which is extended to include effective interactions with explicit density-dependent meson-nucleon couplings. The properties of the pygmy dipole resonance (PDR) are examined in 132 Sn and within isotopic chains, showing that already at moderate proton-neutron asymmetry the PDR peak energy is located above the neutron emission threshold. A method is suggested for determining the size of the neutron skin within an isotopic chain, based on the measurement of the excitation energies of the Gamow-Teller resonance relative to the isobaric analog state. In addition, for the first time the relativistic RHB+RQRPA model, with tensor ω meson-nucleon couplings, is employed in calculations of β-decay half-lives of nuclei of the relevance for the r-process. (orig.)

Self-consistent relativistic QRPA studies of soft modes and spin-isospin resonances in unstable nuclei

Energy Technology Data Exchange (ETDEWEB)

Paar, N. [Technische Universitaet Darmstadt, Institut fuer Kernphysik, Darmstadt (Germany); University of Zagreb, Physics Department, Faculty of Science (Croatia); University of Washington, Institute for Nuclear Theory, Seattle (United States); Niksic, T. [University of Zagreb, Physics Department, Faculty of Science (Croatia); University of Washington, Institute for Nuclear Theory, Seattle (United States); Marketin, T.; Vretenar, D. [University of Zagreb, Physics Department, Faculty of Science (Croatia); Ring, P. [Physik-Department der Technischen Universitaet Muenchen, Garching (Germany)