A systematic approach to vertically excited states of ethylene using configuration interaction and coupled cluster techniques
- Department of Chemistry, Washington State University, Pullman, Washington 99164-4630 (United States)
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700 (United States)
A systematic sequence of configuration interaction and coupled cluster calculations were used to describe selected low-lying singlet and triplet vertically excited states of ethylene with the goal of approaching the all electron, full configuration interaction/complete basis set limit. Included among these is the notoriously difficult, mixed valence/Rydberg {sup 1}B{sub 1u} V state. Techniques included complete active space and iterative natural orbital configuration interaction with large reference spaces which led to variational spaces of 1.8 × 10{sup 9} parameters. Care was taken to avoid unintentionally biasing the results due to the widely recognized sensitivity of the V state to the details of the calculation. The lowest vertical and adiabatic ionization potentials to the {sup 2}B{sub 3u} and {sup 2}B{sub 3} states were also determined. In addition, the heat of formation of twisted ethylene {sup 3}A{sub 1} was obtained from large basis set coupled cluster theory calculations including corrections for core/valence, scalar relativistic and higher order correlation recovery.
- OSTI ID:
- 22308365
- Journal Information:
- Journal of Chemical Physics, Vol. 141, Issue 10; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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