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Spin‐flip approach within time‐dependent density functional tight‐binding method: Theory and applications
Author(s) -
Inamori Mayu,
Yoshikawa Takeshi,
Ikabata Yasuhiro,
Nishimura Yoshifumi,
Nakai Hiromi
Publication year - 2020
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.26197
Subject(s) - density functional theory , time dependent density functional theory , conical intersection , tight binding , spin (aerodynamics) , chemistry , degenerate energy levels , molecular physics , atomic physics , physics , computational chemistry , potential energy , quantum mechanics , electronic structure , thermodynamics
A spin‐flip time‐dependent density functional tight‐binding (SF‐TDDFTB) method is developed that describes target states as spin‐flipping excitation from a high‐spin reference state obtained by the spin‐restricted open shell treatment. Furthermore, the SF‐TDDFTB formulation is extended to long‐range correction (LC), denoted as SF‐TDLCDFTB. The LC technique corrects the overdelocalization of electron density in systems such as charge‐transfer systems, which is typically found in conventional DFTB calculations as well as density functional theory calculations using pure functionals. The numerical assessment of the SF‐TDDFTB method shows smooth potential curves for the bond dissociation of hydrogen fluoride and the double‐bond rotation of ethylene and the double‐cone shape of H 3 as the simplest degenerate systems. In addition, numerical assessments of SF‐TDDFTB and SF‐TDLCDFTB for 39 S 0 / S 1 minimum energy conical intersection (MECI) structures are performed. The SF‐TDDFTB and SF‐TDLCDFTB methods drastically reduce the computational cost with accuracy for MECI structures compared with SF‐TDDFT.