LOCV Calculation Research Articles

LOCV calculation of nuclear matter with relativistic Hamiltonian

The equation of state of symmetric nuclear matter is calculated using the relativistic Hamiltonian (HR) with potentials which have been fitted with the N -N scattering data using the relativistic two-body Hamiltonian ( \( \tilde{{v}}_{{14}}^{}\) and the non-relativistic two-body Hamiltonian, i.e. the Argonne V14 interaction. The boost interaction corrections as well as the relativistic one-body and two-body kinetic energy corrections in cluster expansion energy within the lowest-order-constrained variational method are calculated. It is shown that the relativistic corrections reduce the binding energy by 1.5MeV for \( \tilde{{v}}_{{14}}^{}\) and AV14 interactions. The symmetric nuclear-matter saturation energy is about -16.43 MeV at \( \rho\) = 0.253 (fm-3) with \( \tilde{{v}}_{{14}}^{}\) interaction plus relativistic corrections. Finally, various properties of the symmetric nuclear matter are given and a comparison is made with the other many-body calculations.

LOCV calculations for intermediate phases of nuclear spin-polarized liquid3He ν ↑

Liquid3Heν↑ is studied in a constrained variational approach, where the truncation of the cluster expansion is accounted for by means of an adjustment to the conditions of healing on a two-body Jastrow function. The scheme of calculations involved is very rapid, enabling a detailed study of ground-state saturation properties for intermediate phases of nuclear spin-polarization. Imposing certain consistency requirements on the energy levelsE(ρ0,ν), the equilibrium density ρ0 displays a distinct variation with υ. Results obtained with the HFDHE2, HFD-B(HE) and HFD-B2 twobody interaction models are presently reported.

The effect of three-body cluster energy on LOCV calculation for hot nuclear and neutron matter

The two-body correlation functions, obtained in a lowest-order constrained variational calculation for hot nuclear and neutron matter, with the Reid potential and the explicit inclusion of , are state averaged and used to calculate the three-body cluster energy. The three-body cluster energy is found to vary between about 1 and 2 MeV through and beyond twice the nuclear-matter saturation density for temperatures between 5 and 20 MeV. However, the inclusion of a three-body cluster reduces the nuclear-matter flashing and critical temperatures. A critical temperature of 15.8 MeV and a critical exponent of 0.35 is found. The results of entropy calculations are in good agreement with experimental prediction and other theoretical results. Finally it is shown that by allowing an explicit degree of freedom through the Reid potential up to and including the three-body clusters, the lowest-constrained variational calculation yields other nuclear- and neutron-matter properties close to the available semi-empirical and experimental data at zero and finite temperatures.

LOCV calculations of pressure in nuclear matter at finite temperature

The lowest-order constrained variational method is used to calculate the equation of state of hot nuclear matter. The calculations are performed for a wide range of densities of interest in heavy-ion collisions and astrophysics. A realistic nuclear Hamiltonian that contains N-N and N- Delta interactions and fits N-N scattering as well as nuclear matter saturation data is used. Besides spin, isospin, total angular momentum and density dependence, the correlation functions are also arranged to depend on the temperature of the system. The liquid-vapour phase equilibrium, as well as the behaviour of the effective mass in nuclear matter, is discussed.

Effect of short-range correlation on the nucleon sum rule

The nucleon sum rule is calculated for inelastic electron scattering from nuclear matter in the non-relativistic limit. The effect of short-range correlation (SRC) is presented by using LOCV calculations and the Reid soft-core potential. It is found that the non-relativistic version of Bjorken scaling sets in at a momentum transfer of about 1.1 GeV/c and SRC improves the Coulomb sum rule.

HNC neutron-matter calculations with the Paris potential

A formalism is developed for handling momentum-dependent potentials within the framework of hypernetted chain calculations of dense matter. Some new distribution functions are required and appropriate expressions are obtained for calculating them. The formalism is applied to neutron-matter calculations with the Paris potential. As a test, the first application is to the 1S 0 acting in all partial waves. A more realistic calculation which includes the singlet and triplet potentials in the isospin one channels was used to calculate the equation of state of dense neutron matter and to obtain neutron-star models. LOCV calculations were performed including all partial waves, but attempts to handle state dependence in the correlation function met with complications like those encountered with momentum independent potentials. Significant features of the results with the Paris potential are discussed.

Constrained variational calculations for nuclear matter: N ∗ (1234) and three-body contributions

Two-body correlation functions obtained in a LOCV calculation on nuclear matter using the Reid soft core potential are state averaged and then used to calculate the three-body convergence parameter κ 3 and three-body cluster energy E 3. Results are presented for the pure Reid potential and for the Reid potential supplemented by the transition potential of Green, Niskanen and Sainio which allows for coupling of the NN 1S 0 channel to the NN* (1234) 5D 0 channel.

The magnetic susceptibility of neutron matter

The magnetic susceptibility of neutron matter, interacting through the Reid (1968) soft-core potential, is calculated within the framework of the lowest-order constrained variational technique of Owen, Bishop and Irvine (1977). The magnetic susceptibility predicted by the LOCV calculation is considerably larger than that obtained in Brueckner calculations by Haensel. It is further increased when the N*(1234) degree of freedom is allowed for explicitly. Despite these increases in susceptibility there is no evidence for a ferromagnetic phase transition.

LOCV calculations with a self-consistent treatment of isobars

The results of a series of lowest-order constrained variational calculations for various nucleon fluids are presented. The calculations are based upon the Reid soft-core potential (1968) and allow in a self-consistent fashion for the explicit excitation of a nucleon into an N*(1234) state via a recent transition potential proposed by Green, Niskanen and Sainio (1978). For nuclear matter a binding energy of 16 MeV per nucleon is obtained at a saturation density 0.25 N fm-3. The compressibility of nuclear matter is calculated to be 300 MeV. From a study of asymmetric matter a symmetry coefficient of 33 MeV is obtained. It is found that the inclusion of N*'s in beta-stable matter leads to a suppression of the proton abundance at high densities.

LOCV calculations and the three-body cluster energy in nuclear matter

Two-body correlation functions obtained in a LOCV calculation on nuclear matter using the Reid soft-core potential are state averaged and then used to calculate the three-body convergence parameter kappa 3 and three-body cluster energy E3. kappa 3 is found to be less than 0.1 for Fermi momenta kF<or approximately=1.6 fm-1 and the three-body cluster energy changes the saturation binding energy by a fraction of an MeV per nucleon. The inclusion of the three-body clusters does, however, significantly reduce the saturation density. The authors conclude that, allowing for explicit excitation of the N*(1234) and including up to three-body clusters, the Reid potential yields nuclear matter saturation properties close to those predicted by a semi-empirical analysis.

The saturating effect of N*(1234) on the binding of light nuclei

The binding energy shifts arising from the explicit inclusion of intermediate states involving a N*(1234) are calculated for the light nuclei 4He, 12C and 16O. An oscillator approximation is made for the single-nucleon wavefunctions and the two-body correlations are taken from an LOCV calculation. It is observed that the Pauli effect per nucleon is essentially the same in all three nuclei and is similar to that found in the nucleon fluids. The dispersion effect in the light nuclei is smaller than in the nucleon fluids. It is concluded that these contributions will have a large effect on the saturation of finite nuclei.