title: Generalized Møller-Plesset Partitioning in Multiconfiguration Perturbation Theory.
abstract: Two perturbation (PT) theories are developed starting from a multiconfiguration (MC) zero-order function. To span the configuration space, the theories employ biorthogonal vector sets introduced in the MCPT framework. At odds with previous formulations, the present construction operates with the full Fockian corresponding to a principal determinant, giving rise to a nondiagonal matrix of the zero-order resolvent. The theories provide a simple, generalized Møller-Plesset (MP) second-order correction to improve any reference function, corresponding either to a complete or incomplete model space. Computational demand of the procedure is determined by the iterative inversion of the Fockian, similarly to the single reference MP theory calculated in a localized basis. Relation of the theory to existing multireference (MR) PT formalisms is discussed. The performance of the present theories is assessed by adopting the antisymmetric product of strongly orthogonal geminal (APSG) wave functions as the reference function.
authors.affiliation: Laboratory of Theoretical Chemistry, Institute of Chemistry, Eötvös University, H1518 Budapest POB 32, Hungary, Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University, Tokyo 169-8555, Japan, Department of Theoretical and Computational Molecular Science, Institute for Molecular Science, Okazaki 444-8585, Japan, and Research Institute for Science and Engineering (RISE), Waseda University, Tokyo 169-8555, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Kobayashi
authors.affiliation: Laboratory of Theoretical Chemistry, Institute of Chemistry, Eötvös University, H1518 Budapest POB 32, Hungary, Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University, Tokyo 169-8555, Japan, Department of Theoretical and Computational Molecular Science, Institute for Molecular Science, Okazaki 444-8585, Japan, and Research Institute for Science and Engineering (RISE), Waseda University, Tokyo 169-8555, Japan.
authors.forename: Ágnes
authors.initials: Á
authors.lastname: Szabados
authors.affiliation: Laboratory of Theoretical Chemistry, Institute of Chemistry, Eötvös University, H1518 Budapest POB 32, Hungary, Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University, Tokyo 169-8555, Japan, Department of Theoretical and Computational Molecular Science, Institute for Molecular Science, Okazaki 444-8585, Japan, and Research Institute for Science and Engineering (RISE), Waseda University, Tokyo 169-8555, Japan.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Nakai
authors.affiliation: Laboratory of Theoretical Chemistry, Institute of Chemistry, Eötvös University, H1518 Budapest POB 32, Hungary, Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University, Tokyo 169-8555, Japan, Department of Theoretical and Computational Molecular Science, Institute for Molecular Science, Okazaki 444-8585, Japan, and Research Institute for Science and Engineering (RISE), Waseda University, Tokyo 169-8555, Japan.
authors.forename: Péter R
authors.initials: PR
authors.lastname: Surján