An accurate and linear-scaling method for calculating charge-transfer excitation energies and diabatic couplings

M. Pavanello, T. van Voorhis, L. Visscher, J. Neugebauer

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Quantum-mechanical methods that are both computationally fast and accurate are not yet available for electronic excitations having charge transfer character. In this work, we present a significant step forward towards this goal for those charge transfer excitations that take place between non-covalently bound molecules. In particular, we present a method that scales linearly with the number of non-covalently bound molecules in the system and is based on a two-pronged approach: The molecular electronic structure of broken-symmetry charge-localized states is obtained with the frozen density embedding formulation of subsystem density-functional theory; subsequently, in a post-SCF calculation, the full-electron Hamiltonian and overlap matrix elements among the charge-localized states are evaluated with an algorithm which takes full advantage of the subsystem DFT density partitioning technique. The method is benchmarked against coupled-cluster calculations and achieves chemical accuracy for the systems considered for intermolecular separations ranging from hydrogen-bond distances to tens of Ångstroms. Numerical examples are provided for molecular clusters comprised of up to 56 non-covalently bound molecules. © 2013 American Institute of Physics.
Original languageEnglish
Article number054101
JournalJournal of Chemical Physics
Volume138
Issue number5
DOIs
Publication statusPublished - 2013

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