Spin-Conserved and Spin-Flip Optical Excitations from the Bethe-Salpeter Equation Formalism.

ABSTRACT: Like adiabatic time-dependent density-functional theory (TD-DFT), the Bethe-Salpeter equation (BSE) formalism of many-body perturbation theory, in its static approximation, is "blind" to double (and higher) excitations, which are ubiquitous, for example, in conjugated molecules like polyenes. Here, we apply the spin-flip ansatz (which considers the lowest triplet state as the reference configuration instead of the singlet ground state) to the BSE formalism in order to access, in particular, double excitations. The present scheme is based on a spin-unrestricted version of the GW approximation employed to compute the charged excitations and screened Coulomb potential required for the BSE calculations. Dynamical corrections to the static BSE optical excitations are taken into ac

SUBMITTER: Monino E 

PROVIDER: S-EPMC8154368 | biostudies-literature | 2021 May

REPOSITORIES: biostudies-literature