title: Scalar relativistic calculations of hyperfine coupling constants using ab initio density matrix renormalization group method in combination with third-order Douglas-Kroll-Hess transformation: case studies on 4d transition metals.
abstract: We have developed a new computational scheme for high-accuracy prediction of the isotropic hyperfine coupling constant (HFCC) of heavy molecules, accounting for the high-level electron correlation effects, as well as the scalar-relativistic effects. For electron correlation, we employed the ab initio density matrix renormalization group (DMRG) method in conjunction with a complete active space model. The orbital-optimization procedure was employed to obtain the optimized orbitals required for accurately determining the isotropic HFCC. For the scalar-relativistic effects, we initially derived and implemented the Douglas-Kroll-Hess (DKH) hyperfine coupling operators up to the third order (DKH3) by using the direct transformation scheme. A set of 4d transition-metal radicals consisting of Ag atom, PdH, and RhH2 were chosen as test cases. Good agreement between the isotropic HFCC values obtained from DMRG/DKH3 and experiment was archived. Because there are no available gas-phase values for PdH and RhH2 radicals in the literature, the results from the present high-level theory may serve as benchmark data.
authors.affiliation: The Graduate University for Advanced Studies , Myodaiji, Okazaki, Aichi 444-8585, Japan.
authors.forename: Tran
authors.initials: T
authors.lastname: Nguyen Lan
authors.affiliation: The Graduate University for Advanced Studies , Myodaiji, Okazaki, Aichi 444-8585, Japan.|Department of Theoretical and Computational Molecular Science, Institute for Molecular Science , Okazaki, Aichi 444-8585, Japan.|Japan Science and Technology Agency, PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Kurashige
authors.affiliation: The Graduate University for Advanced Studies , Myodaiji, Okazaki, Aichi 444-8585, Japan.|Department of Theoretical and Computational Molecular Science, Institute for Molecular Science , Okazaki, Aichi 444-8585, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Yanai