September 15, 2014 to October 10, 2014
Nordita, Stockholm
Europe/Stockholm timezone

Afternoon Session: Coupled Cluster Methods

Sep 24, 2014, 2:30 PM
2h
132:028 (Nordita, Stockholm)

132:028

Nordita, Stockholm

Speaker

Piotr Piecuch

Description

SINGLE-REFERENCE COUPLED-CLUSTER METHODS FOR MULTI-REFERENCE MOLECULAR PROBLEMS Piotr Piecuch, Jun Shen, Nicholas P. Bauman, and Jared A. Hansen Accurate modeling of chemical reactions and photochemistry requires a balanced treatment of dynamical and non-dynamical many-electron correlation effects. The popular single-reference coupled-cluster (CC) and equation-of-motion CC (EOMCC) methods, such as CCSD(T) and EOMCCSD, capture the former effects very effectively, but have difficulties with the latter ones, whereas multi-reference CC theories that are supposed to capture both types of correlations continue facing unresolved problems. This talk will discuss pragmatic ways of addressing this situation via the completely renormalized and active-space CC and EOMCC theories, and their recent merger via the novel CC(P;Q) formalism, which reproduces the nearly exact relative and total electronic energies in ground and excited states at the small fractions of computer costs of other methods that aim at similar accuracies. The development of the singly and doubly ionized and electron-attached variants of the active-space EOMCC methodology, which provide an excellent description of electronic excitations in radicals, biradicals, and other similar open-shell systems around closed shells at the low computational costs compared to the parent approaches, will be addressed, too.

Presentation materials