We present a simple quasi-diabatization scheme applicable to spectroscopic studies that can be applied using any wavefunction for which one-electron properties and transition properties can be calculated. The method is based on rotation of a pair (or set) of adiabatic states to minimize the difference between the given transition property at a reference geometry of high symmetry (where the quasi-diabatic states and adiabatic states coincide) and points of lower symmetry where quasi-diabatic quantities are desired. Compared to other quasi-diabatization techniques, the method requires no special coding, facilitates direct comparison between quasi-diabatic quantities calculated using different types of wavefunctions, and is free of any selection of configurations in the definition of the quasi-diabatic states. On the other hand, the method appears to be sensitive to multi-state issues, unlike recent methods we have developed that use a configurational definition of quasi-diabatic states. Results are presented and compared with two other recently developed quasi-diabatization techniques.
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http://dx.doi.org/10.1063/1.4940426 | DOI Listing |
J Phys Chem A
January 2025
Department of Chemistry, University of Louisville, Louisville, Kentucky 40292, United States.
Triplet-triplet energy transfer (TEnT) is of particular interest in various photochemical, photobiological, and energy science processes. It involves the exchange of spin and energy of electrons between two molecular fragments. Here, quasi-diabatic self-consistent field solutions were used to obtain the diabatic states involved in TEnT.
View Article and Find Full Text PDFJ Chem Phys
October 2024
Institut für Physikalische und Theoretische Chemie, Julius-Maximilians-Universität Würzburg, Emil-Fischer-Strasse 42, 97074 Würzburg, Germany.
J Phys Chem Lett
October 2024
Zhejiang Key Laboratory of Excited-State Energy Conversion and Energy Storage, Department of Chemistry, Zhejiang University, Hangzhou 310058, China.
Due to the cuspidal ridges of adiabatic potential energy surfaces (PESs) and singularities of nonadiabatic couplings (NACs), obtaining an analytical expression for the adiabatic Hamiltonian is difficult. Thereby, nonadiabatic dynamics simulations are often carried out on-the-fly, which is time-consuming. This motivates us to construct quasi-diabatic representations, which have smooth PESs and diabatic couplings.
View Article and Find Full Text PDFJ Chem Theory Comput
August 2024
Institut für Physikalische und Theoretische Chemie, Julius-Maximilians-Universität, Würzburg 97074, Germany.
We introduce a novel methodology for simulating the excited-state dynamics of extensive molecular aggregates in the framework of the long-range corrected time-dependent density-functional tight-binding fragment molecular orbital method (FMO-LC-TDDFTB) combined with the mean-field Ehrenfest method. The electronic structure of the system is described in a quasi-diabatic basis composed of locally excited and charge-transfer states of all fragments. In order to carry out nonadiabatic molecular dynamics simulations, we derive and implement the excited-state gradients of the locally excited and charge-transfer states.
View Article and Find Full Text PDFJ Chem Phys
June 2024
National Research Council Canada, 100 Sussex Drive, Ottawa, Ontario K1A 0R6, Canada.
We describe a procedure for the calculation of quasi-diabatic states within the recently introduced DFT/MRCI(2) framework [S. P. Neville and M.
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