Ab initio compact group model potentials for describing environment effects in cluster calculations

• Published in: Journal of computational chemistry Vol. 20; no. 11; pp. 1145 - 1152
• Main Authors: Cruz Hernández, Norge, Sanz, Javier Fdez
• Format: Journal Article
• Language: English
• Published: New York John Wiley & Sons, Inc 01.08.1999
• Subjects: ab initio calculations; environment; group model potentials; rotation
• ISSN: 0192-8651; 1096-987X
• DOI: 10.1002/(SICI)1096-987X(199908)20:11<1145::AID-JCC5>3.0.CO;2-I

A method for the determination of ab initio group model potentials within the Hartree–Fock framework is reported. Following the theory of separability of many electron systems, a new way to incorporate the effect of complete chemical entities by means of polycenter compact model potentials is presented. The interaction between active and frozen electrons is partitioned as a sum of long‐ and short‐range terms. The long‐range term is described as the effect of −2e charges placed in the center of the charge of the frozen group molecular orbitals; the short‐range one, the exchange and Pauli repulsion, is developed as a spectral representation in a nonorthogonal basis set. An algorithm to solve the problem associated with the rotation of the polycenter model potential is presented and implemented in an all‐purpose quantum chemical program. In order to check the method, a group model potential for H2O was obtained and tested. ©1999 John Wiley & Sons, Inc. J Comput Chem 20: 1145–1152, 1999