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Light‐induced excited spin‐state trapping in spin crossover model system
Author(s) -
Karmakar Shiladitya,
Ghosh Debashree,
SahaDasgupta Tanusri
Publication year - 2020
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.26122
Subject(s) - complete active space , time dependent density functional theory , excited state , chemistry , density functional theory , coupled cluster , atomic physics , perturbation theory (quantum mechanics) , degrees of freedom (physics and chemistry) , potential energy , spin states , relaxation (psychology) , multireference configuration interaction , physics , spin crossover , quantum mechanics , molecular physics , computational chemistry , configuration interaction , molecule , crystallography , basis set , psychology , social psychology
We computationally investigate the light‐induced excited spin‐state trapping (LIESST) in a spin crossover (SCO) model system, derived out of [Fe(abpt) 2 (NCS) 2 ] consisting of Fe(II) SCO center coordinated by bidenate as well as monodentate ligands. For this purpose, we use two complementary techniques: (a) time‐dependent density functional theory (TDDFT) with the choice of different exchange‐correlation functional and (b) multireference approach of complete active space self‐consistent field and complete active‐space second‐order perturbation (CASPT2) theory. We calculate the potential energy curves (PECs) of low‐energy states, as well as spin‐orbit couplings at crossing points of these PECs. Inputting these pieces of information, and the information related to nuclear degrees of freedom within the Franck‐Condon theory, we compute the relaxation rates of possible LIESST mechanisms, as suggested by the two approaches. Based on our findings, we conclude that TDDFT may not be an unreasonable approach to estimate the relaxation rates of real complexes, consisting of several tens to several hundreds of atoms, given its computationally inexpensive nature compared with that of the multireference approaches.