The implementation details of the universal state-selective (USS) multi-reference coupled cluster (MRCC) formalism with singles and doubles (USS(2)) are discussed on the example of several benchmark systems. We demonstrate that the USS(2) formalism is capable of improving accuracies of state specific multi-reference coupled-cluster (MRCC) methods based on the Brillouin-Wigner and Mukherjee’s sufficiency conditions. Additionally, it is shown that the USS(2) approach significantly alleviates problems associated with the lack of invariance of MRCC theories upon the rotation of active orbitals. We also discuss the perturbative USS(2) formulations that significantly reduce numerical overhead of the full USS(2) method.
Revised: January 17, 2017 |
Published: October 28, 2016
Citation
Brabec J., S. Banik, K. Kowalski, and J. Pittner. 2016.Perturbative universal state-selective correction for a state-specific multi-reference coupled cluster methods.Journal of Chemical Physics 145, no. 16:Article No. 164106.PNNL-SA-116405.doi:10.1063/1.4965826