Spin‐flip approach within time‐dependent density functional tight‐binding method: Theory and applications. Issue 16 (27th March 2020)

• Record Type: Journal Article
• Authors: Inamori, Mayu; Yoshikawa, Takeshi; Ikabata, Yasuhiro; Nishimura, Yoshifumi; Nakai, Hiromi
• Is Part Of: Journal of computational chemistry. Volume 41:Issue 16(2020)
• Page Start: 1538
• Page End: 1548
• Publication Date: 2020-03-27
• Subjects: conical intersection -- degenerate phenomena -- long‐range correction -- spin‐flip -- time‐dependent density functional tight‐binding method; Chemistry -- Data processing -- Periodicals; 542.85
• DOI: 10.1002/jcc.26197
• Languages: English
• ISSNs: 0192-8651

Abstract

Abstract: 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 H3 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. Abstract : A spin‐flip time‐dependent density functional tight‐binding (SF‐TDDFTB) method is developed. The numerical assessments of SF‐TDDFTB for 39 S0 /S1 conical intersection (CI) structures are performed. The figure shows the differences between SF‐TDDFT and SF‐TDDFTB in red for 1, 4‐diphenyl‐1, 3‐butadiene, 9‐methypurine, dibenzofuran, and ketene. The SF‐TDDFTB method drastically reduce the computational cost with accuracy for CI structures compared with SF‐TDDFT.