Multipole approximation of distant pair energies in local MP2 calculations

by Hetzer, G.; Pulay, P.; Werner, H. J.

An approximation for treating the weak correlation of distant pairs in local MP2 calculations by multipole expansions is proposed. This leads to computational savings in the transformation of the two-electron integrals, which is the bottleneck in MP2 calculations. The method works well for orbital pairs that are at least 7 bohr apart. The accuracy is mainly limited by the neglect of ionic excitations in the first-order wavefunction, while the error of the multipole expansion is almost negligible.

Journal
Chemical Physics Letters
Volume
290
Issue
1-3
Year
1998
Start Page
143-149
URL
https://dx.doi.org/10.1016/s0009-2614(98)00491-6
ISBN/ISSN
1873-4448; 0009-2614
DOI
10.1016/s0009-2614(98)00491-6