Journal or Book Title
Journal of Chemical Physics
A multi-configuration quasi-degenerate second-order perturbation method based on the occupation restricted multiple active space (ORMAS-PT/ORMAS) reference wavefunction is presented. ORMAS gives one the ability to approximate a complete active space self-consistent field (CASSCF) wavefunction using only a subset of the configurations from the CASSCF space. The essential idea behind ORMAS-PT is to use the multi-reference Møller-Plesset formalism to correct the ORMAS reference energy. A computational scheme employing direct CI methodology is presented. Several tests are presented to demonstrate the performance of the ORMAS-PT method.
Copyright 2011 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.
American Institute of Physics
Roskop, Luke and Gordon, Mark S., "Quasi-Degenerate Second-Order Perturbation Theory for Occupation Restricted Multiple Active Space Self-Consistent Field Reference Functions" (2011). Chemistry Publications. 561.