F. Arias de Saavedra

Effective mass of one He 4 atom in liquid He 3

A microscopic calculation of the effective mass of one [sup 4]He impurity in homogeneous liquid [sup 3]He at zero temperature is performed for an extended Jastrow-Slater wave function, including two- and three-body dynamical correlations and also backflow correlations between the [sup 4]He atom and the particles in the medium. The effective mass at equilibrium density, [ital m][l angle][ital main][r angle][sub 4][sup *]/[ital m][sub 4]=1.21, is in very good agreement with the recent experimental determination by Edwards [ital et] [ital al]. The three-particle correlations appear to give a small contribution to the effective mass and different approximations for the three-particle distribution function give almost identical results for [ital m][sub 4][sup *]/[ital m][sub 4].

Model calculations of doubly closed shell nuclei in CBF theory III. jj coupling and isospin dependence

Abstract Correlated basis function theory and Fermi hypernetted chain technique are extended to study medium-heavy, doubly closed shell nuclei in the jj coupling scheme, with different single-particle wave functions for protons and neutrons and isospin-dependent two-body correlations. Central semirealistic interactions are used. Ground-state energies, one-body densities, distribution functions and momentum distributions are calculated for 12 C, 16 O, 40 Ca, 48 Ca and 208 Pb nuclei. The values of the ground-state energies provided by isospin-dependent correlations are significantly lower than those obtained with isospin-independent correlations. In finite nuclear systems, the two-body Euler equations provide correlation functions variationally more effective than those obtained with the same technique in infinite nuclear matter.

Ground state of N5Z doubly closed shell nuclei in correlated basis function theory

~Received 6 October 1997! The ground state properties of N5Z doubly closed shell nuclei are studied within correlated basis function theory. A truncated version of the Urbana v 14 realistic potential, with spin, isospin, and tensor components, is adopted, together with state-dependent correlations. Fermi hypernetted chain integral equations are used to evaluate the density, distribution function, and ground state energy of 16 O and 40 Ca. The nuclear matter single operator chain approximation is extended to finite nuclear systems, to deal with the noncommuting part of the correlation operators. The results favorably compare with variational Monte Carlo estimates, when available, and provide a first substantial check of the accuracy of the cluster summation method for state-dependent correlations. We achieve in finite nuclei a treatment of noncentral interactions and correlations having, at least, the same level of accuracy as in nuclear matter. This opens the way for a microscopic study of the medium heavy nuclei ground state using present day realistic Hamiltonians. @S0556-2813~98!00104-6#

Single-particle and electron-pair densities at the origin in the ground state of helium-like ions

Here we study the single-particle and the electron-pair densities for the ground state of two-electron atomic systems using the wavefunctions which provide the best values for the energy known up to now. Special attention is paid to the convergence of some properties of the densities when we increase the dimension of the basis used. With these functions we have increased significantly the precision in the determination of the single-particle and the electron-pair densities at the origin and, therefore, of Katos cusp conditions.

Renormalized Fermi hypernetted chain approach in medium–heavy nuclei

Abstract The application of the correlated basis function theory and of the Fermi hypernetted chain technique, to the description of the ground state of medium–heavy nuclei is reviewed. We discuss how the formalism, originally developed for symmetric nuclear matter, should be changed in order to describe finite nuclear systems, with different number of protons and neutrons. This approach allows us to describe doubly closed shell nuclei by using microscopic nucleon–nucleon interactions. We presents results of numerical calculations done with two-nucleon interactions of Argonne type, implemented with three-body forces of Urbana type. Our results regard ground-state energies, matter, charge and momentum distributions, natural orbits, occupation numbers, quasi-hole wave functions and spectroscopic factors of 12 C, 16 O, 40 Ca, 48 Ca and 208 Pb nuclei.

Effects of state dependent correlations on nucleon density and momentum distributions

The proton momentum and density distributions of closed shell nuclei are calculated with a model treating short-range correlations up to first order in the cluster expansion. The validity of the model is verified by comparing the results obtained using purely scalar correlations with those produced by finite nuclei Fermi hypernetted chain calculations. State dependent correlations are used to calculate momentum and density distributions of {sup 12}C, {sup 16}O, {sup 40}Ca, and {sup 48}Ca, and the effects of their tensor components are studied. {copyright} {ital 1997} {ital The American Physical Society}

Ground states of medium-heavy doubly-closed-shell nuclei in correlated-basis function theory

The correlated-basis function theory is applied to the study of medium-heavy doubly-closed-shell nuclei with different wave functions for protons and neutrons and in the jj coupling scheme. State-dependent correlations including tensor correlations are used. Realistic two-body interactions of Argonne and Urbana type, together with three-body interactions, have been used to calculate ground-state energies and density distributions of the {sup 12}C, {sup 16}O, {sup 40}Ca, {sup 48}Ca, and {sup 208}Pb nuclei.

Correlated model forΛhypernuclei

We study the properties of hypernuclei containing one lambda hyperon in the framework of the correlated basis function theory with Jastrow correlations. Fermi hypernetted chain integral equations are derived and used to evaluate energies and one-body densities of lambda hypernuclei having a doubly closed shell nucleonic core in the jj coupling scheme, from Carbon to Lead. We also study hypernuclei having the least bound neutron substituted by the lambda particle. The semi-realistic Afnan and Tang nucleon-nucleon potential and Bodmer and Usmani lambda-nucleon potential are adopted. The effect of many-body forces are considered by means either of a three body lambda-nucleon-nucleon potential of the Argonne type or of a density dependent modification of the lambda-nucleon interaction, fitted to reproduce the lambda binding energy in nuclear matter. While Jastrow correlations underestimate the attractive contribution of the three body

Calculations of the one- and two-body densities in two-electron atomic systems

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Ferromagnetic transition of a two-component Fermi gas of hard spheres

interaction, the density dependent potential provides a good description of the lambda binding energies over all the nuclear masses range, in spite of the relative simplicity of the model.