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Updated: Jun 4, 2025
Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids
Published on: May 27, 2020
Computing Excited States of Very Large Systems with Range-Separated Hybrid Functionals and the Exact Integral
1Theoretical Chemistry Group, Molecular Chemistry, Materials and Catalysis Division (MOST), Institute of Condensed Matter and Nanosciences, Université Catholique de Louvain, Place Louis Pasteur 1, B-1348 Louvain-la-Neuve, Belgium.
Abstract:
Simplified quantum chemistry (sQC) methods can routinely compute excited states for very large systems in an "all-atom" fashion. They are viable alternatives to regular multiscale schemes. sQC methods have the advantage of accounting explicitly for all of the environment at a quantum mechanical (QM) level. The treatment of charge-transfer states is now improved by the native implementation of range-separated hybrid (RSH) exchange-correlation functionals into the eXact integral simplified time-dependent density functional theory (XsTD-DFT). After the RSH XsTD-DFT/TDA scheme was benchmarked, XsTD-DFT(/TDA) ultraviolet/visible absorption, circular dichroism (CD), and/or two-photon absorption (2PA) spectra were directly compared to the results of experiments for four challenging and increasingly large systems: eYFP model system, Λ-shaped multimodular D-π-A-π-D'-π-A-π-D chromophore, mixed donor/acceptor ligand Pd(II) double cage [3BF4@Pd4DA8-], and the photoactive yellow protein (PYP). Among the results, this study shows that an "all-atom" approach is unavoidable for reproducing absorption and CD spectra of PYP because one of the main transitions involves a local excitation on a tryptophan.
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