Description of ground and excited electronic states by ensemble density functional method with extended active space

作者：Filatov Michael^*; Martinez Todd J; Kim Kwang S

来源：Journal of Chemical Physics, 2017, 147(6): 064104.

DOI：10.1063/1.4996873

An extended variant of the spin-restricted ensemble-referenced Kohn-Sham (REKS) method, the REKS(4,4) method, designed to describe the ground electronic states of strongly multireference systems is modified to enable calculation of excited states within the time-independent variational formalism. The new method, the state-interaction state-averaged REKS(4,4), i.e., SI-SA-REKS(4,4), is capable of describing several excited states of a molecule involving double bond cleavage, polyradical character, or multiple chromophoric units. We demonstrate that the new method correctly describes the ground and the lowest singlet excited states of a molecule (ethylene) undergoing double bond cleavage. The applicability of the new method for excitonic states is illustrated with pi stacked ethylene and tetracene dimers. We conclude that the new method can describe a wide range of multireference phenomena. Published by AIP Publishing.

• 出版日期2017-8-14