Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Physical Review C

Fermi hypernetted-chain calculation of the half-diagonal two-body density matrix of model nuclear matter

Μ. Petraki, Eirene Mavrommatis, J. W. Clark

Published Jun 25, 2001• 3 citations
Publisher

Abstract

The half-diagonal two-body density matrix ${\ensuremath{\rho}}_{2h}({\mathbf{r}}_{1},{\mathbf{r}}_{2},{\mathbf{r}}_{{1}^{\ensuremath{'}}})$ is a key quantity in theoretical descriptions of nucleon knockout reactions at intermediate energies, due to its central role in treatments of the propagation and final-state interactions of ejected nucleons in the nuclear medium. This quantity is calculated for a simple model of the ground state of infinite symmetrical nuclear matter, based on a Jastrow-correlated wave function and a Fermi hypernetted-chain analysis. The dependence of ${\ensuremath{\rho}}_{2h}$ on the variables ${r}_{{11}^{\ensuremath{'}}}=|{\mathbf{r}}_{1}\ensuremath{-}{\mathbf{r}}_{{1}^{\ensuremath{'}}}|,$ ${r}_{12}=|{\mathbf{r}}_{1}\ensuremath{-}{\mathbf{r}}_{2}|,$ and the angle $\ensuremath{\theta}$ between ${\mathbf{r}}_{1}\ensuremath{-}{\mathbf{r}}_{{1}^{\ensuremath{'}}}$ and ${\mathbf{r}}_{1}\ensuremath{-}{\mathbf{r}}_{2}$ is investigated in some detail. Significant departures from ideal Fermi gas behavior in certain domains reflect the importance of short-range correlations and their interplay with statistical correlations. The quality of approximations to ${\ensuremath{\rho}}_{2h}$ proposed by Gersch et al., Rinat, and Silver is assessed by comparison with the Fermi hypernetted-chain results.

DOI
10.1103/physrevc.64.024301

Related papers

Fermi hypernetted-chain evaluation of a generalized momentum distribution for model nuclear matter

Eirene Mavrommatis, Μ. Petraki, J. W. Clark

The generalized momentum distribution n(p,Q), related to the half-diagonal two-body density matrix ${\mathrm{\ensuremath{\rho}}}_{2\mathrm{h}}$(${\mathbf{r}}_{1}$,${\mathbf{r}}_{2}$,${\mathbf{r}}_{1}^{\ensuremath{'}}$) by Fourier transformation in the variables ${\mathbf{r}}_{1}$-${\mathbf{r}}_{1}^{\ensuremath{'}}$ and ${\mathbf{r}}_{1}$-${\mathbf{r}}_{2}$, plays a key role in the description of final-state interactions in the nuclear medium and other strongly interacting many-body systems. The function n(p,Q) is explored for two Jastrow-correlated models of infinite nuclear matter within a Fermi hypernetted-chain procedure. Significant departures from ideal Fermi gas behavior in certain kinematic domains provide signatures of the strong short-range correlations contained in these models. However, such deviations are less prominent than in earlier calculations based on low-order cluster truncations; correspondingly, violations of the sequential relation are greatly reduced. Simple prescriptions for improved low-cluster-order approximations to n(p,Q) are suggested by analysis of the results of the Fermi hypernetted-chain evaluation. These results are also used to assess the quality of Silver's approximation n(p,Q)\ensuremath{\approx}n(p)[S(Q)-1] for the generalized momentum distribution in terms of the ordinary momentum distribution n(p) and the static structure function S(Q), with findings that have potential implications for the interpretation of data from inclusive electron scattering by nuclei at high momentum transfers.

Physical Review C•Apr 1, 1995•7 citations

Study of the Generalized Momentum Distribution of Model Nuclear Matter

Eirene Mavrommatis, Μ. Petraki, J. W. Clark

Valuable information on the correlation structure of the nuclear medium is stored in the generalized momentum distribution n(p,Q), the Fourier transform of the half-diagonal two-body density matrix ρ_{2η}(r_1,r_2,r'). In this paper, we present a numerical calculation of n(p,Q) for two Jastrow-correlated models of symmetrical nuclear matter based on the structural decomposition of n(p,Q) derived by Ristig and Clark and on a Fermi-hypernetted-chain procedure. Results exhibit significant departures from the ideal Fermi gas case in certain kinematic domains; this behaviour indicates the strong short-range correlations present in these models. Nevertheless, such deviations are less prominent than in earlier low- cluster-order calculations. The results are also used to judge the quality of Silver's approximation for n(p,Q).

HNPS Advances in Nuclear Physics•Feb 19, 2020•0 citations

Two body density matrix of model nuclear matter

E. Mavromanatis, Μ. Petraki, J. W. Clark

A lowest-cluster-order variational calculation of the half-diagonal two-body density matrix ρ2(r1,r2,r’1) and the corresponding generalized momentum distribution n(p.Q) is performed for three representative models of nuclear matter containing central correlations. Dynamical correlations produce significant deviations from the results for a noninteracting Fermi gas. Calculations axe in progress that include higherorder cluster corrections as well as state-dependent correlations

HNPS Advances in Nuclear Physics•Dec 5, 2019•0 citations

Ground-state properties of spin-aligned deuterium

M. F. Flynn, J. W. Clark, E. Krotscheck +2 more

Ground-state properties of nuclear-spin-aligned deuterium are studied within the method of correlated basis functions (CBF), using Fermi-hypernetted-chain (FHNC) techniques to evaluate the requisite matrix elements of the Hamiltonian and identity attendant to a Jastrow choice of correlation operator. Results are presented for the ground-state energies of three hypothetical species of this system, calculated to low order in CBF perturbation theory, taking account of two- and three-body CBF effective interactions. Also included are data on the Jastrow momentum distribution and radial distribution function, computed using the FHNC scheme. These findings are supplemented by benchmark variational Monte Carlo results on the energy and radial distribution function. The three deuterium species provide examples of strongly interacting Fermi fluids, intermediate in coupling strength between nuclear matter and liquid $^{3}\mathrm{He}$.

Physical review. B, Condensed matter•Sep 1, 1985•18 citations

Neutron matter calculations by the Fermi-hypernetted-chain method

Børge Arntsen, Erlend Østgaard

The Fermi-hypernetted-chain method for quantum many-body calculations is studied and investigated in some detail by calculations of the ground-state energy for neutron matter. The calculations are done for five different two-body potentials and results are compared with other theoretical results. Our Fermi-hypernetted-chain results are rather close to results obtained by lowest-order constrained variation calculations, and the results are quite dependent on the chosen potential, especially at high densities.

Physical Review C•Jul 1, 1984•3 citations

A variational theory of nuclear matter

Robert B. Wiringa

The hypotheticai system of nucleons known as nuclear matter provides a very interesting field of study with relevance to both nuclear physics and astrophysics. The task of finding nucleon-nucleon potentials that explain the empirical properties of nuclear matter, as well as the two-body data, has been hampered by the lack of an adequate many-body theory for treating the complicated forces involved. Realistic nucleon-nucleon potentials have strong spin, isospin, tensor and spin-orbit components which induce correspondingly strong correlations in nuclear matter. In this thesis we present a variational theory designed to cope with these complicated correlations. To place the theory in perspective we give an overview of several different many-body theories and compare their predictions in the somewhat simpler systems of the 4He and 3He liquids, and for a simple central potential model of nuclear matter. The variational theory is then developed, starting with the choice of wave function. A generalized Jastrow product of two-body correlation functions containing central, spin, isospin, tensor, and spin-orbit operators is used. The correlation function is generated by a series of two-body Schrodinger equations with boundary conditions which require the wave function to heal at a distance d. The wave function is parameterized by d and by the magnitudes of the non-central correlations. Expectation values with variational wave functions of the Jastrow type may be studied conveniently with generalized Mayer diagrams. Diagram rules are given and a general diagrammatic cluster expansion is derived. It is an expansion in powers of commutators of the non-central operators, and in their absence reduces to the usual Mayer cluster expansion. Evaluation of diagrams in the cluster expansion is complicated by the presence of the non-commuting operators. Some simple rules and useful methods for calculating the contribution due to the central, spin, isospin, and tensor operators are given. Spin-orbit operators are neglected beyond this point, but the approach used is extendible to them. Large classes of diagrams contributing to an expectation value can be summed by means of integral equations. The development of single chain, hypernetted chain, and Fermi hypernetted chain (FHNC) equations for central correlations is reviewed. The chain summation methods are extended to sum single operator chains (SOC) for the non-central operators. Methods are also given for treating the leading commutator corrections in the expansi0n by simple vertex factors. The energy expectation value for potentials with six operators are evaluated using the FHNC/SOC functions, with an exact treatment of the commutators involved. The energy is found to have a minimum with respect to variations in all parameters. Results of calculations with model potentials based on the Reid, Bethe-Johnson, Hamada-Johnston, and Gammel-Thaler potentials are reported. A crude estimate of the effect of the neglected spin-orbit potentials on the nuclear matter binding energy and saturation density indicates that it could be significant. A correct treatment of the spin-orbit potentials is the next major step that should be taken.

•Jan 1, 1978•0 citations
The half-diagonal two-body density matrix \ensuremathρ2h(r1,r2,r1\ensuremath′){\ensuremath{\rho}}_{2h}({\mathbf{r}}_{1},{\mathbf{r}}_{2},{\mathbf{r}}_{{1}^{\ensuremath{'}}})\ensuremathρ2h​(r1​,r2​,r1\ensuremath′​) is a key quantity in theoretical descriptions of nucleon knockout reactions at intermediate energies, due to its central role in treatments of the propagation and final-state interactions of ejected nucleons in the nuclear medium. This quantity is calculated for a simple model of the ground state of infinite symmetrical nuclear matter, based on a Jastrow-correlated wave function and a Fermi hypernetted-chain analysis. The dependence of \ensuremathρ2h{\ensuremath{\rho}}_{2h}\ensuremathρ2h​ on the variables r11\ensuremath′=∣r1\ensuremath−r1\ensuremath′∣,{r}_{{11}^{\ensuremath{'}}}=|{\mathbf{r}}_{1}\ensuremath{-}{\mathbf{r}}_{{1}^{\ensuremath{'}}}|,r11\ensuremath′​=∣r1​\ensuremath−r1\ensuremath′​∣, r12=∣r1\ensuremath−r2∣,{r}_{12}=|{\mathbf{r}}_{1}\ensuremath{-}{\mathbf{r}}_{2}|,r12​=∣r1​\ensuremath−r2​∣, and the angle \ensuremathθ\ensuremath{\theta}\ensuremathθ between r1\ensuremath−r1\ensuremath′{\mathbf{r}}_{1}\ensuremath{-}{\mathbf{r}}_{{1}^{\ensuremath{'}}}r1​\ensuremath−r1\ensuremath′​ and r1\ensuremath−r2{\mathbf{r}}_{1}\ensuremath{-}{\mathbf{r}}_{2}r1​\ensuremath−r2​ is investigated in some detail. Significant departures from ideal Fermi gas behavior in certain domains reflect the importance of short-range correlations and their interplay with statistical correlations. The quality of approximations to \ensuremathρ2h{\ensuremath{\rho}}_{2h}\ensuremathρ2h​ proposed by Gersch et al., Rinat, and Silver is assessed by comparison with the Fermi hypernetted-chain results.
The generalized momentum distribution n(p,Q), related to the half-diagonal two-body density matrix ${\mathrm{\ensuremath{\rho}}}_{2\mathrm{h}}$(r1{\mathbf{r}}_{1}r1​,r2{\mathbf{r}}_{2}r2​,${\mathbf{r}}_{1}^{\ensuremath{'}}$) by Fourier transformation in the variables r1{\mathbf{r}}_{1}r1​-${\mathbf{r}}_{1}^{\ensuremath{'}}$ and r1{\mathbf{r}}_{1}r1​-r2{\mathbf{r}}_{2}r2​, plays a key role in the description of final-state interactions in the nuclear medium and other strongly interacting many-body systems. The function n(p,Q) is explored for two Jastrow-correlated models of infinite nuclear matter within a Fermi hypernetted-chain procedure. Significant departures from ideal Fermi gas behavior in certain kinematic domains provide signatures of the strong short-range correlations contained in these models. However, such deviations are less prominent than in earlier calculations based on low-order cluster truncations; correspondingly, violations of the sequential relation are greatly reduced. Simple prescriptions for improved low-cluster-order approximations to n(p,Q) are suggested by analysis of the results of the Fermi hypernetted-chain evaluation. These results are also used to assess the quality of Silver's approximation n(p,Q)\ensuremath{\approx}n(p)[S(Q)-1] for the generalized momentum distribution in terms of the ordinary momentum distribution n(p) and the static structure function S(Q), with findings that have potential implications for the interpretation of data from inclusive electron scattering by nuclei at high momentum transfers.
Valuable information on the correlation structure of the nuclear medium is stored in the generalized momentum distribution n(p,Q), the Fourier transform of the half-diagonal two-body density matrix ρ_{2η}(r_1,r_2,r'). In this paper, we present a numerical calculation of n(p,Q) for two Jastrow-correlated models of symmetrical nuclear matter based on the structural decomposition of n(p,Q) derived by Ristig and Clark and on a Fermi-hypernetted-chain procedure. Results exhibit significant departures from the ideal Fermi gas case in certain kinematic domains; this behaviour indicates the strong short-range correlations present in these models. Nevertheless, such deviations are less prominent than in earlier low- cluster-order calculations. The results are also used to judge the quality of Silver's approximation for n(p,Q).
Ground-state properties of nuclear-spin-aligned deuterium are studied within the method of correlated basis functions (CBF), using Fermi-hypernetted-chain (FHNC) techniques to evaluate the requisite matrix elements of the Hamiltonian and identity attendant to a Jastrow choice of correlation operator. Results are presented for the ground-state energies of three hypothetical species of this system, calculated to low order in CBF perturbation theory, taking account of two- and three-body CBF effective interactions. Also included are data on the Jastrow momentum distribution and radial distribution function, computed using the FHNC scheme. These findings are supplemented by benchmark variational Monte Carlo results on the energy and radial distribution function. The three deuterium species provide examples of strongly interacting Fermi fluids, intermediate in coupling strength between nuclear matter and liquid 3He^{3}\mathrm{He}3He.
The Fermi-hypernetted-chain method for quantum many-body calculations is studied and investigated in some detail by calculations of the ground-state energy for neutron matter. The calculations are done for five different two-body potentials and results are compared with other theoretical results. Our Fermi-hypernetted-chain results are rather close to results obtained by lowest-order constrained variation calculations, and the results are quite dependent on the chosen potential, especially at high densities.
The hypotheticai system of nucleons known as nuclear matter provides a very interesting field of study with relevance to both nuclear physics and astrophysics. The task of finding nucleon-nucleon potentials that explain the empirical properties of nuclear matter, as well as the two-body data, has been hampered by the lack of an adequate many-body theory for treating the complicated forces involved. Realistic nucleon-nucleon potentials have strong spin, isospin, tensor and spin-orbit components which induce correspondingly strong correlations in nuclear matter. In this thesis we present a variational theory designed to cope with these complicated correlations. To place the theory in perspective we give an overview of several different many-body theories and compare their predictions in the somewhat simpler systems of the 4He and 3He liquids, and for a simple central potential model of nuclear matter. The variational theory is then developed, starting with the choice of wave function. A generalized Jastrow product of two-body correlation functions containing central, spin, isospin, tensor, and spin-orbit operators is used. The correlation function is generated by a series of two-body Schrodinger equations with boundary conditions which require the wave function to heal at a distance d. The wave function is parameterized by d and by the magnitudes of the non-central correlations. Expectation values with variational wave functions of the Jastrow type may be studied conveniently with generalized Mayer diagrams. Diagram rules are given and a general diagrammatic cluster expansion is derived. It is an expansion in powers of commutators of the non-central operators, and in their absence reduces to the usual Mayer cluster expansion. Evaluation of diagrams in the cluster expansion is complicated by the presence of the non-commuting operators. Some simple rules and useful methods for calculating the contribution due to the central, spin, isospin, and tensor operators are given. Spin-orbit operators are neglected beyond this point, but the approach used is extendible to them. Large classes of diagrams contributing to an expectation value can be summed by means of integral equations. The development of single chain, hypernetted chain, and Fermi hypernetted chain (FHNC) equations for central correlations is reviewed. The chain summation methods are extended to sum single operator chains (SOC) for the non-central operators. Methods are also given for treating the leading commutator corrections in the expansi0n by simple vertex factors. The energy expectation value for potentials with six operators are evaluated using the FHNC/SOC functions, with an exact treatment of the commutators involved. The energy is found to have a minimum with respect to variations in all parameters. Results of calculations with model potentials based on the Reid, Bethe-Johnson, Hamada-Johnston, and Gammel-Thaler potentials are reported. A crude estimate of the effect of the neglected spin-orbit potentials on the nuclear matter binding energy and saturation density indicates that it could be significant. A correct treatment of the spin-orbit potentials is the next major step that should be taken.