Physics Commons^™

The Generality Of The Guga Mrci Approach In Columbus For Treating Complex Quantum Chemistry, Hans Lischka, Ron Shepard, Thomas Müller, Peter G. Szalay, Russell M. Pitzer, Adelia J. A. Aquino, Carol A. Parish, Et Al.

Chemistry Faculty Publications

The core part of the program system COLUMBUS allows highly efficient calculations using variational multireference (MR) methods in the framework of configuration interaction with single and double excitations (MR-CISD) and averaged quadratic coupled-cluster calcu- lations (MR-AQCC), based on uncontracted sets of configurations and the graphical unitary group approach (GUGA). The availability of analytic MR-CISD and MR-AQCC energy gradients and analytic nonadiabatic couplings for MR-CISD enables exciting applications including, e.g., investigations of π-conjugated biradicaloid compounds, calculations of multitudes of excited states, development of dia- batization procedures, and furnishing the electronic structure information for on-the-fly surface nonadiabatic dynamics. With fully vari- ational …