Diagrammatic many-body perturbation expansion for atoms and molecues: III. Third-order ring energies

Abstract

The non-relativistic Schrodinger equation for the electronic Catalogue number: ACXH structure of atomic and molecular systems is considered within the Born—Oppenheimer approximation. Program obtainable from: CPC Program Library, Queen’s University of Belfast, N. Ireland (see application form this Method of solution issue) The diagrammatic many-body perturbation expansion is employed through third-order in the energy and first-order C’omputer: IBM 360/91 in the wave function. All many-body terms are evaluated. The calculations are performed within the algebraic approximation [1] in which the one-electron state functions are parameterInstallation: The Johns Hopkins University Applied Physics ized by expansion in a finite set of basis functions. Computer Laboratory algorithms are presented for the evaluation of third-order hole—particle, or ring, diagrams. Operating system used: ASP Restrictions on the complexity of the problem Programming language: FORTRAN IV The reference wave function must be a non-degenerate, closed-shell Hartree—Fock determinant. The current program High speed storage required: 200 kilobytes is restricted to systems containing up to twenty electrons described by basis sets containing a maximum of 35 spatial Numberof bits in a byte: 8 functions. These latter restrictions are easily changed.