Abstract

The objective of this thesis is to compare the upper bound of the ground state energy of doubly ionized carbon (C⁺⁺) to the lower bound obtained by reduced density matrices.

To make a fair comparison, the number of orbitals used in both is the same, namely ten. The upper bound is obtained by use of the standard Rayleigh-Ritz Variational Principle which states ⟨Ψ|H|Ψ⟩ ≥ Eo(H) were Eo(H) is the exact ground state energy, H is the Hamiltonian, and Ψ is the trial wave function.

Abstract An improved ground state wavefunction for Helium for use in density matrix calculations has been obtained. This improvement was achieved by the introduction into the expansion for the singlet S-state wavefunction for Helium, of a term containing explicit angular dependence. This angular term was constructed so as to preserve angular momentum symmetry by being an eigenfunction of the two-particle, angular momentum operator with eigenvalue zero, as is required for S-states. The results give...

Abstract The intention of this paper is to determine some of the properties of the screened coulomb [sic] potential, and look into its validity as a model for observed emission spectra of hydrogen plasmas. Some variational methods will be examined and the problem of finding upper bounds to the excited states of atoms will also be investigated. The variational method is then applied to the anomoly [sic] of the...

Abstract A survey of the relative efficiency of various approximate methods for solving the non-relativistic Schroedinger Equation [sic] is made. In particular, a comparison is made of the results obtained for the problem of a simple harmonic oscillator perturbed by λx∝, (∝ =3,4 ) while using the Rayleigh-Ritz variational principle, Linear Variation of Functions, and the Reyleigh-Schroedinger [sic]...

Abstract

A recently developed theory enabling the construction of density matrices which are expressible in terms of a given spin geminal set and which are a nearly N-representable as possible is discussed.

Calculation of lower bounds to the ground state energy of the C⁺⁺ ion is performed utilizing reduced density matrices subject to the continuously variable N-representability constraint determined by the above mentioned theory.

Introduction Section II of this thesis considers the problem of an electron which is both bound in an attractive screened Coulomb potential and under the simultaneous influence of an external electric field. The total energy Hamiltonian, for the case of one electron immersed in a plasma, is derived. A suitable ground state wavefunction is chosen which incorporates the approximate induced dipole character of the charge configuration when subjected to the plasma's free particle uniform electric field....

Abstract Since the original work by [Sir Geoffrey Ingram] Taylor several authors have reported theoretical and experimental calculations on Rayleigh-Taylor and other gravitational instabilities for various fluid and field geometries of magnetohydrodynamical interest. In the particular case of the theta pinch geometry, a Rayleigh-Taylor instability is found to occur in the first (adiabatic) expansion stage of the columns, with experimental growth rates of the proper order of magnitude for this type...

Abstract The Schrodinger equation for an atomic system which possesses N electrons has 3N independent variables and is perhaps one of the most difficult questions in physics to solve. Because of the complex nature of the problem, only approximate methods can be used. One such method is the Rayleigh-Ritz Variational principle [sic] which minmizes over all [sic] space, and the minimum is the ground state energy. Another method is by...

Abstract The non-relativistic energies have been determined for the singlet and triple S states (1¹S, 2¹S and 2³S) of the helium like two electron system. Calculations were based on a finite set of orbitals of the order 7. The set, which includes Laguerre polynomials, is expressed as a superposition of configurations built up from one-electron wave functions or orbitals and approximates the exact wave function. Application of the variational principle leads to a system of linear equations....