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 newmethod 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 π stacked ethylene and tetracene dimers. We conclude that the new method can describe a wide range of multireference phenomena.
Filatov, Michael, et al. "Description of ground and excited electronic states by ensemble density functional method with extended active space." Journal of Chemical Physics, vol. 147, no. 6, Aug. 2017. https://doi.org/10.1063/1.4996873
Filatov, Michael, Martínez, Todd J., & Kim, Kwang S. (2017). Description of ground and excited electronic states by ensemble density functional method with extended active space. Journal of Chemical Physics, 147(6). https://doi.org/10.1063/1.4996873
Filatov, Michael, Martínez, Todd J., and Kim, Kwang S., "Description of ground and excited electronic states by ensemble density functional method with extended active space," Journal of Chemical Physics 147, no. 6 (2017), https://doi.org/10.1063/1.4996873
@article{osti_1390629,
author = {Filatov, Michael and Martínez, Todd J. and Kim, Kwang S.},
title = {Description of ground and excited electronic states by ensemble density functional method with extended active space},
annote = {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 newmethod 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 π stacked ethylene and tetracene dimers. We conclude that the new method can describe a wide range of multireference phenomena.},
doi = {10.1063/1.4996873},
url = {https://www.osti.gov/biblio/1390629},
journal = {Journal of Chemical Physics},
issn = {ISSN 0021-9606},
number = {6},
volume = {147},
place = {United States},
publisher = {American Institute of Physics (AIP)},
year = {2017},
month = {08}}