# A reduce package for exact Coulomb interaction matrix elements

## Description

Abstract Title of program: R12 interaction matrix elements Catalogue number: ABBN Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland (see application form in this issue) Computer: IBM compatible PC/ Cray 1 M Operating system: MS DOS 3.x/ COS 1.15 Programming language used: Reduce 3.2 High speed storage required: 512 KB for PC/ 290 Kwords for Cray No. of bits in a word: 64 No. of lines in combined program and test deck: 500 Title of program: R12 INTERACTION MATRIX ELEMENTS Catalogue Id: ABBN_v1_0 Nature of problem With atomic physics and quantum chemistry numerous numerical computations and also recent theoretical investigations require the evaluation of the quantum mechanical expectation values for the Coulomb interaction 1/r12 or inverse interaction operator r12 = |r1 - r2|. For Slater-functions and hydrogenic wavefunctions such expectation values can in principle be determined exactly. This fact is used in a package of Reduce procedures which calculate the wanted matrix elements and other related quant ... Versions of this program held in the CPC repository in Mendeley Data ABBN_v1_0; R12 INTERACTION MATRIX ELEMENTS; 10.1016/0010-4655(88)90051-3 This program has been imported from the CPC Program Library held at Queen's University Belfast (1969-2019)