A new method for computing the properties of negative ion resonances with applications to H sub 2 sup minus , H sup minus and HF sup minus

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1988

OSTI ID:5931345

DeRose, E F

In this dissertation a new ab initio method for computing the properties of molecular and atomic negative ion resonances is presented. The first step of the procedure is an MCSF calculation to obtain a set of molecular orbitals for a CI calculation. The CI calculation is then carried out to 10{sup {minus}5} a.u. energy convergence of the lowest 15 or so roots of the CI matrix. Next a variation of the Feshbach projection method is applied to the CI states to project out the resonances from the CI space. The property used to partition the CI space is the electronic expectation value (z{sup 2}). Small values of (z{sup 2}) are the result of the localization of the extra electron when it is temporarily attached to the neutral molecule. The continuum states will have large values of (z{sup 2}) because the extra electron is delocalized. If appropriate, the expectation value (r{sup 2}) could be used for the projection. The method has been used to study H{sub 2}{sup {minus}} states of {sup 2}{Sigma}{sub u}{sup +} symmetry. As a calibration of the method, the technique was also applied to {sup 1}S states of H{sup {minus}} for which very accurate experimental and theoretical results have been reported. The potential energy curves of the first three {sup 2}{Sigma}{sub u}{sup +} resonance states of H{sub 2}{sup {minus}} were calculated, and the asymptotic assignments for the three resonances were made. The results for the lowest {sup 1}S resonance of H{sup {minus}} agree remarkably well with the accurate literature results. The ab initio electronic structure code which was used in the calculations on H{sub 2}{sup {minus}} and H{sup {minus}} has been extensively modified for applications to larger systems, such as {sup 2}{Sigma}{sup +} states of HF{sup {minus}}.

• Research Organization: Illinois Univ., Chicago, IL (USA)
• OSTI ID: 5931345
• Country of Publication: United States
• Language: English

Related Subjects

640302* -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
74 ATOMIC AND MOLECULAR PHYSICS
ANIONS
ATOMS
CALCULATION METHODS
CHARGED PARTICLES
COMPARATIVE EVALUATIONS
ELECTRONIC STRUCTURE
ENERGY LEVELS
HYDROFLUORIC ACID
HYDROGEN COMPOUNDS
HYDROGEN IONS
INORGANIC ACIDS
IONS
MOLECULAR IONS
MOLECULAR ORBITAL METHOD