A systematic approach to vertically excited states of ethylene using configuration interaction and coupled cluster techniques

作者：Feller David^*; Peterson Kirk A; Davidson Ernest R

来源：Journal of Chemical Physics, 2014, 141(10): 104302.

DOI：10.1063/1.4894482

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 B-1(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 x 10(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 B-2(3u) and B-2(3) states were also determined. In addition, the heat of formation of twisted ethylene (3)A(1) was obtained from large basis set coupled cluster theory calculations including corrections for core/valence, scalar relativistic and higher order correlation recovery.

• 出版日期2014-9-14