Perturbative expansion of non-orthogonal product approach for charge-transfer states

19 April 2022, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


Modeling of the excited states of multichromophoric systems is crucial for the understanding of photosynthesis functioning. The excitonic Hamiltonian method is widely used for such calculations. Excited states of the combined system are constructed from the wave functions of individual chromophores while their interactions are described by excitonic couplings. In the current study we enhance earlier proposed non-orthogonal product approach to incorporate dynamic correlation effects accounted for by the multireference perturbation theory. We discuss the problems of constructing the excitonic Hamiltonian including charge-transfer states for the molecular systems where the overlap contribution to the excitonic couplings is non-negligible. The benchmark calculations were performed for a model system. It was shown that the overlap component of the excitonic coupling is of great importance. The enhanced method provides an accurate description of the excited states energies and other properties.


perturbation theory
charge transfer
excitonic Hamiltonian
excitonic coupling
wave functions' overlap
non-orthogonal CI

Supplementary materials

Supplementary Information
The Supplementary includes geometry of the complex and distance dependencies of wave function composition


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