Communication: Application of state-specific multireference coupled cluster methods to core-level excitations

Journal Article · Wed Nov 07 04:00:00 EST 2012 · Journal of Chemical Physics, 137(17):Article No.171101

DOI:https://doi.org/10.1063/1.4764355· OSTI ID:1059187

Brabec, Jiri; Bhaskaran-Nair, Kiran; Govind, Niranjan; Pittner, Jiri; Kowalski, Karol

The concept of the model space underlying multireference coupled-cluster (MRCC) formulations is a powerful tool to deal with complex correlation effects for various electronic states. Here, we demonstrate that iterative state-specific MRCC methods (SS-MRCC) based on properly defined model spaces can be used to describe core-level excited states even when canonical Hartree-Fock orbitals are utilized. We show that the SS-MRCC models with single and double excitations (SSMRCCSD) are comparable in accuracy to high-level single reference equation-of-motion coupled cluster (EOMCC) formalism. We also demonstrate that the SS-MRCC methods are capable of providing high accuracy results without experiencing numerical problems of the EOMCC methods.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1059187
• Report Number(s): PNNL-SA-90515; 44892
• Journal Information: Journal of Chemical Physics, 137(17):Article No.171101, Journal Name: Journal of Chemical Physics, 137(17):Article No.171101
• Country of Publication: United States
• Language: English

Related Subjects

Environmental Molecular Sciences Laboratory
Hartree-Fock
MRCC
Multireference
coupled cluster
electronic states
excitations