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Tayloring standard TDDFT approaches for computing UV/Vis transitions in thiocarbonyl chromophores
Author(s) -
Preat Julien,
Jacquemin Denis,
Perpète Eric A.
Publication year - 2007
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.21544
Subject(s) - zindo , time dependent density functional theory , excitation , basis set , chromophore , quantum chemical , chemistry , ground state , computational chemistry , quantum chemistry , basis (linear algebra) , set (abstract data type) , density functional theory , physics , atomic physics , mathematics , quantum mechanics , molecule , computer science , supramolecular chemistry , geometry , programming language
We report the development of an accurate computational procedure for the calculation of the n → π* (λ max− 1 ) and π → π* (λ max− 2 ) transitions of a set of thiocarbonyl derivatives. To ensure converged results, all calculations are carried out using the 6‐311+G(2df,p) basis set for time‐dependent calculations, and the 6‐311G(2df,p) for the ground‐state geometrical optimization. Starting with two hybrids, PBE0 and B3LYP, the Hartree–Fock exchange percentage (α) used is optimized in order to reach excitation energies that fit experimental data. It turns out that BLYP(α) is the more adequate functional for calibration. For the n → π* excitation, the optimal α value lies in the 0.10–0.20 interval, whereas for the π → π* process setting α equal to 0.10 provides the most accurate results. The corresponding mean absolute errors (MAE) are limited to 17 nm for λ max− 1 , and to 10 nm for λ max− 2 , allowing a consistent and accurate prediction of both transitions. We also assess the merits of the ZINDO//AM1 scheme and it turns out that the semi‐empirical method only provides a poor prediction of the λ max of thiocarbonyl derivatives, especially for the n → π* transition. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008