TY  - JOUR
AU  - Mai, Sebastian
AU  - Mueller, Thomas
AU  - Plasser, Felix
AU  - Marquetand, Philipp
AU  - Lischka, Hans
AU  - González, Leticia
TI  - Perturbational treatment of spin-orbit coupling for generally applicable high-level multi-reference methods
JO  - The journal of chemical physics
VL  - 141
IS  - 7
SN  - 1089-7690
CY  - Melville, NY
PB  - American Institute of Physics
M1  - FZJ-2014-05996
SP  - 074105 
PY  - 2014
AB  - An efficient perturbational treatment of spin-orbit coupling within the framework of high-level multireference techniques has been implemented in the most recent version of the COLUMBUS quantum chemistry package, extending the existing fully variational two-component (2c) multi-reference configuration interaction singles and doubles (MRCISD) method. The proposed scheme follows related implementations of quasi-degenerate perturbation theory (QDPT) model space techniques. Our model space is built either from uncontracted, large-scale scalar relativistic MRCISD wavefunctions or based on the scalar-relativistic solutions of the linear-response-theory-based multi-configurational averaged quadratic coupled cluster method (LRT-MRAQCC). The latter approach allows for a consistent, approximatively size-consistent and size-extensive treatment of spin-orbit coupling. The approach is described in detail and compared to a number of related techniques. The inherent accuracy of the QDPT approach is validated by comparing cuts of the potential energy surfaces of acrolein and its S, Se, and Te analoga with the corresponding data obtained from matching fully variational spin-orbit MRCISD calculations. The conceptual availability of approximate analytic gradients with respect to geometrical displacements is an attractive feature of the 2c-QDPT-MRCISD and 2c-QDPT-LRT-MRAQCC methods for structure optimization and ab inito molecular dynamics simulations
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000340714600008
C6  - pmid:25149773
DO  - DOI:10.1063/1.4892060
UR  - https://juser.fz-juelich.de/record/172531
ER  -