title: SplitGAS Method for Strong Correlation and the Challenging Case of Cr2.
abstract: A new multiconfigurational quantum chemical method, SplitGAS, is presented. The configuration interaction expansion, generated from a generalized active space, GAS, wave function is split in two parts, a principal part containing the most relevant configurations and an extended part containing less relevant, but not negligible, configurations. The partition is based on an orbital criterion. The SplitGAS method has been employed to study the HF, N2, and Cr2 molecules. The results on these systems, especially on the challenging, multiconfigurational Cr2 molecule, are satisfactory. While SplitGAS is comparable with the GASSCF method in terms of memory requirements, it performs better than the complete active space method followed by second-order perturbation theory, CASPT2, in terms of equilibrium bond length, dissociation energy, and vibrational properties.
authors.affiliation: Department of Chemistry, Supercomputing Institute, and Chemical Theory Center, University of Minnesota , Minneapolis, Minnesota 55455, United States.|Department of Physical Chemistry, University of Geneva , Switzerland, CH-1211.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Li Manni
authors.affiliation: Department of Chemistry, Supercomputing Institute, and Chemical Theory Center, University of Minnesota , Minneapolis, Minnesota 55455, United States.
authors.forename: Dongxia
authors.initials: D
authors.lastname: Ma
authors.affiliation: Department of Physical Chemistry, University of Geneva , Switzerland, CH-1211.|Center for Biomolecular Nanotechnologies @UNILE, Italian Institute of Technology (IIT) , Via Barsanti, I-73010 Arnesano (LE), Italy.|Department of Chemistry - Ångström, The Theoretical Chemistry Programme, Uppsala University , P.O. Box 518, SE-751 20 Uppsala, Sweden.
authors.forename: Francesco
authors.initials: F
authors.lastname: Aquilante
authors.affiliation: Department of Chemistry, Aarhus University , Langelandsgade 140, 8000 Aarhus C, Denmark.
authors.forename: Jeppe
authors.initials: J
authors.lastname: Olsen
authors.affiliation: Department of Chemistry, Supercomputing Institute, and Chemical Theory Center, University of Minnesota , Minneapolis, Minnesota 55455, United States.
authors.forename: Laura
authors.initials: L
authors.lastname: Gagliardi