title: Communication: Application of state-specific multireference coupled cluster methods to core-level excitations.
abstract: 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 Hartree-Fock orbitals are utilized. We show that the SS-MRCC models with single and double excitations are comparable in accuracy to high-level single reference equation-of-motion coupled cluster (EOMCC) formalism.
authors.affiliation: J. Heyrovský Institute of Physical Chemistry, v.v.i., Academy of Sciences of the Czech Republic, Dolejškova 3, 18223 Prague 8, Czech Republic.
authors.forename: Jiří
authors.initials: J
authors.lastname: Brabec
authors.forename: Kiran
authors.initials: K
authors.lastname: Bhaskaran-Nair
authors.forename: Niranjan
authors.initials: N
authors.lastname: Govind
authors.forename: Jiří
authors.initials: J
authors.lastname: Pittner
authors.forename: Karol
authors.initials: K
authors.lastname: Kowalski