# Four-index integral transformation exploiting symmetry

## Description

Abstract We present a Fortran implementation of four-index integral transformation in the LCAO-MO (linear combination of atomic orbitals–molecular orbitals) framework that exploits symmetry. Electron correlation calculations, such as configuration interaction (CI) calculations, usually require electron repulsion integrals to be transformed to a molecular orbital basis from a basis using atomic orbitals. In large molecular systems it is vital to exploit the sparsity of integrals in making this transfor... Title of program: SYM4TR Catalogue Id: ADUW_v1_0 Nature of problem Molecular orbital calculations including electron correlation effects usually require electron repulsion integrals to be transformed from an atomic orbital (AO) basis to a molecular orbital (MO) basis. By exploiting the sparsity of molecular integrals, the computational cost and memory needed for the transformation are minimized. Versions of this program held in the CPC repository in Mendeley Data ADUW_v1_0; SYM4TR; 10.1016/j.cpc.2004.01.008 This program has been imported from the CPC Program Library held at Queen's University Belfast (1969-2018)