Programs in Physics & Physical Chemistry
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|Manuscript Title: Computer generation of Feynman diagrams for perturbation theory. II. Program description.|
|Authors: H.C. Wong, J. Paldus|
|Program title: P.T. DIAGRAM GENERATION|
|Catalogue identifier: AAKH_v1_0|
Distribution format: gz
|Journal reference: Comput. Phys. Commun. 6(1973)9|
|Programming language: Fortran.|
|Computer: S 360/75.|
|Operating system: OS 360-MVT, HASP II.|
|RAM: 46K words|
|Word size: 8|
|Keywords: Molecular physics, Electronic structure, Many-body problem, Goldstone perturbation, Green functions, Correlation energy, Ionization potentials, Electron affinities, Excitation energies, Feyman diagrams, Goldstone diagrams, Hugenholtz diagrams, Diagramatic expansions, General purpose, Theoretical methods.|
Nature of problem:
Program finds pertinent topologically distinct diagrams of the Hugenholtz type, which are necessary in calculations of correlation energies, ionization potentials and electron affinities, excitation energies and double ionization processes using the field theoretical form of the perturbation theory.
Diagrams are conveniently represented as strings of integers and the topological equivalences are represented by appropriate permutations of these integers. All possible diagrams (i.e. strings) are generated and only the so-called "essentially distinct" are retained. The details of the method used are described in part I of Comp. Phys. Commun 6(1973)1.
Either vacuum or Green-function diagrams may be calculated. In the latter case, both particle-hole and hole-hole diagrams are generated and the so called self-energy diagrams are singled out. By leaving out the free line in the self-energy diagrams we get the one-particle Green- function diagrams.
The CPU time for the calculation of all possible 3rd order vacuum and Green-function diagrams (both p-h and p-p) is ~ 1 min on an IBM 360/75. The given test example required 0.16 min of CPU time.
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