Computing excited states of condensed-phase systems is a challenging undertaking. We attack the problem by exploiting the machinery of Constrained Density Functional Theory, and have recently proposed [1] a variational method for calculating low-lying excited states of complex systems: eXcited Constrained DFT (XCDFT). We present a thermally activated variation of XCDFT [2] that is capable of computing electronic excitations in systems with strong excited state multireference character. The method assumes that the smearing provided by the Fermi-Dirac distribution function is enough to account for the fractional occupation character of the excited state’s 1-RDM in multireference systems. We benchmark this method on well-established test sets and find that electronic temperatures as small as 500 K are sufficient to fully capture the multireference character delivering quantitative agreement of the computed excited-ground state density differences with benchmark calculations. In addition, exploiting population analyses, XCDFT can generate excitation-localized states [3]. With this new method for generating diabatic states for excitation energy transfer (EET), we compute the electronic coupling for EET on several dimer systems. XCDFT EET couplings compare well with reported values in the literature.<br/>

Multireference and diabatic valence excited states by constrained DFT

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.