title: Cholesky Decomposition-Based Multiconfiguration Second-Order Perturbation Theory (CD-CASPT2): Application to the Spin-State Energetics of Co(III)(diiminato)(NPh).
abstract: The electronic structure and low-lying electronic states of a Co(III)(diiminato)(NPh) complex have been studied using multiconfigurational wave function theory (CASSCF/CASPT2). The results have been compared to those obtained with density functional theory. The best agreement with ab initio results is obtained with a modified B3LYP functional containing a reduced amount (15%) of Hartree-Fock exchange. A relativistic basis set with 869 functions has been employed in the most extensive ab initio calculations, where a Cholesky decomposition technique was used to overcome problems arising from the large size of the two-electron integral matrix. It is shown that this approximation reproduces results obtained with the full integral set to a high accuracy, thus opening the possibility to use this approach to perform multiconfigurational wave-function-based quantum chemistry on much larger systems relative to what has been possible until now.
authors.affiliation: Department of Theoretical Chemistry, Chemical Center, University of Lund, P.O. Box 124, S-221 00 Lund, Sweden, and Department of Chemistry, University of Tromsø, N-9037 Tromsø, Norway.
authors.forename: Francesco
authors.initials: F
authors.lastname: Aquilante
authors.affiliation: Department of Theoretical Chemistry, Chemical Center, University of Lund, P.O. Box 124, S-221 00 Lund, Sweden, and Department of Chemistry, University of Tromsø, N-9037 Tromsø, Norway.
authors.forename: Per-Åke
authors.initials: PÅ
authors.lastname: Malmqvist
authors.affiliation: Department of Theoretical Chemistry, Chemical Center, University of Lund, P.O. Box 124, S-221 00 Lund, Sweden, and Department of Chemistry, University of Tromsø, N-9037 Tromsø, Norway.
authors.forename: Thomas Bondo
authors.initials: TB
authors.lastname: Pedersen
authors.affiliation: Department of Theoretical Chemistry, Chemical Center, University of Lund, P.O. Box 124, S-221 00 Lund, Sweden, and Department of Chemistry, University of Tromsø, N-9037 Tromsø, Norway.
authors.forename: Abhik
authors.initials: A
authors.lastname: Ghosh
authors.affiliation: Department of Theoretical Chemistry, Chemical Center, University of Lund, P.O. Box 124, S-221 00 Lund, Sweden, and Department of Chemistry, University of Tromsø, N-9037 Tromsø, Norway.
authors.forename: Björn Olof
authors.initials: BO
authors.lastname: Roos