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

C-452 Computer Physics Communications 14 ( 1978) 91-98 © North-Holland Publishing Company DIAGRAMMATIC MANY-BODY PERTURBATION EXPANSION FOR ATOMS AND MOLECULES: III. THIRD-ORDER RING ENERGIES Stephen WILSON Applied Physics Laboratory, The Johns Hopkins University, Laurel, Maryland 2081 O, USA and NASA Institute for Space Studies, Goddard Space Flight Centre, New York, New York 10025, USA Received 1 September 1977; in revised form PROGRAM SUMMARY Title o f program: MBPT RING DIAGRAMS Catalogue number: ACXH Computer: IBM 360/91 Installation: The Johns Hopkins University Applied Physics Laboratory Operating system used: ASP Programming language: FORTRAN IV High speed storage required: 200 kilobytes Number of bits in a byte: 8 Overlay structure: 6 segments, 2 nodes Number of magnetic tapes required: none Other peripherals used: disc, line printer, card reader Number of cards in combined program and test deck: 739 CPC library subprograms used: Cat. no. Title ACXF MBPT ORGANIZATION ACXG MBPT LADDER DIAGRAMS Ref. in CPC 14 (1978) this issue 14 (1978) this issue Keywords: quantum chemistry, atomic, molecular, electronic, structure, diagram, many-body, perturbation theory, third- order, hole-particle diagram, ring diagram. Nature o f the physical rpoblem The non-relativistic Schr6dinger equation for the electronic structure of atomic and molecular systems is considered within the Born-Oppenheimer approximation. Method of solution The diagrammatic many-body perturbation expansion is employed through third-order in the energy and first-order 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 parameter- ized by expansion in a finite set of basis functions. Computer algorithms are presented for the evaluation of third-order hole-particle, or ring, diagrams. Restrictions on the complexity of the problem The reference wave function must be a non-degenerate, closed-shell Hartree-Fock determinant. The current program is restricted to systems containing up to twenty electrons described by basis sets containing a maximum of 35 spatial functions. These latter restrictions are easily changed. Typical runnh~g time Running times are strongly dependent on the size of the basis set and the number of electrons. Some timing data has been presented previously [1,2]. The test run requires 1.5 s of of CPU time on an IBM 360/91 computer for the execution of the subprograms described in this paper. Usual features of the program This program is designed for use with those described in the two preceding papers [3,41 . References [1] S. Wilson and D.M. Silver, Phys. Rev. A14 (1976) 1949. [2] S. Wilson and D.M. Silver, J. Chem. Phys. 67 (1977) 5400.

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

Page 1: Diagrammatic many-body perturbation expansion for atoms and molecues: III. Third-order ring energies

C-452

Computer Physics Communications 14 ( 1978) 91 -98 © North-Holland Publishing Company

DIAGRAMMATIC MANY-BODY PERTURBATION EXPANSION FOR ATOMS AND MOLECULES: III. THIRD-ORDER RING ENERGIES

Stephen WILSON Applied Physics Laboratory, The Johns Hopkins University, Laurel, Maryland 2081 O, USA and NASA Institute for Space Studies, Goddard Space Flight Centre, New York, New York 10025, USA

Received 1 September 1977; in revised form

PROGRAM SUMMARY

Title of program: MBPT RING DIAGRAMS

Catalogue number: ACXH

Computer: IBM 360/91

Installation: The Johns Hopkins University Applied Physics Laboratory

Operating system used: ASP

Programming language: FORTRAN IV

High speed storage required: 200 kilobytes

Number of bits in a byte: 8

Overlay structure: 6 segments, 2 nodes

Number of magnetic tapes required: none

Other peripherals used: disc, line printer, card reader

Number of cards in combined program and test deck: 739

CPC library subprograms used:

Cat. no. Title ACXF MBPT ORGANIZATION ACXG MBPT LADDER DIAGRAMS

Ref. in CPC 14 (1978) this issue 14 (1978) this issue

Keywords: quantum chemistry, atomic, molecular, electronic, structure, diagram, many-body, perturbation theory, third- order, hole-particle diagram, ring diagram.

Nature of the physical rpoblem The non-relativistic Schr6dinger equation for the electronic structure of atomic and molecular systems is considered within the Born-Oppenheimer approximation.

Method of solution The diagrammatic many-body perturbation expansion is employed through third-order in the energy and first-order 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 parameter- ized by expansion in a finite set of basis functions. Computer algorithms are presented for the evaluation of third-order hole-particle, or ring, diagrams.

Restrictions on the complexity of the problem The reference wave function must be a non-degenerate, closed-shell Hartree-Fock determinant. The current program is restricted to systems containing up to twenty electrons described by basis sets containing a maximum of 35 spatial functions. These latter restrictions are easily changed.

Typical runnh~g time Running times are strongly dependent on the size of the basis set and the number of electrons. Some timing data has been presented previously [1,2]. The test run requires 1.5 s of of CPU time on an IBM 360/91 computer for the execution of the subprograms described in this paper.

Usual features of the program This program is designed for use with those described in the two preceding papers [3,41 .

References [1] S. Wilson and D.M. Silver, Phys. Rev. A14 (1976) 1949. [2] S. Wilson and D.M. Silver, J. Chem. Phys. 67 (1977) 5400.