Studies in the Method of Correlated Basis Functions
Abstract
In this paper exploratory studies are begun on various physical systems within the method of Correlated Basis Functions (CBF) developed by Feenberg and Clark. The purpose of these studies is twofold: first, to test the CBF method on real manybody systems of current interest and second to provide additional theoretical framework through which CBF theory may be better understood. The ('16)O nucleus is studied first: the variational groundstate energy of the system is calculated assuming simple model twonucleon interactions. Some lowlying oddparity excitations of ('16)O are then computed using a simplified CBF configurationmixing approach. The results are compared with an equally simplified BruecknerBethe theory calculation done by earlier workers. Second, a generalized HolsteinPrimakoff (HP) theory is worked out for the Nbody Bose system. A variant of earlier hydrodynamic approaches to the interacting Bose gas is derived which is free of operatorordering difficulties. The HP theory is further extended to derive a correlated time dependent HartreeFock approximation (TDHF); this is shown to lead to the BijlFeynman phononroton spectrum. The correlated TDHF approach is next applied to the onedimensional planar ferromagnet CsNiF(,3). The approach yields a spectrum of elementary excitations in this system in good quantitative agreement with currently available experimental data. Lastly, the HP theory is worked out for interacting Nbody Fermi systems. This theory extends earlier derivations of the random phase approximation (RPA): calculation of systematic corrections to the RPA is reduced to ordinary perturbation theory.
 Publication:

Ph.D. Thesis
 Pub Date:
 1984
 Bibcode:
 1984PhDT........64M
 Keywords:

 HOLSTEINPRIMAKOFF;
 Physics: General