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Modeling emission features of salicylidene aniline molecular crystals: A QM / QM ’ approach
Author(s) -
Presti Davide,
Labat Frédéric,
Pedone Alfonso,
Frisch Michael J.,
Hratchian Hrant P.,
Ciofini Ilaria,
Cristina Menziani Maria,
Adamo Carlo
Publication year - 2016
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.24282
Subject(s) - oniom , density functional theory , aniline , chemistry , molecule , computational chemistry , singlet state , excited state , qm/mm , chemical physics , cluster (spacecraft) , molecular dynamics , atomic physics , physics , organic chemistry , computer science , programming language
A new computational protocol relying on the use of electrostatic embedding, derived from QM/QM’ ONIOM calculations, to simulate the effect of the crystalline environment on the emission spectra of molecular crystals is here applied to the β‐form of salicylidene aniline (SA). The first singlet excited states ( S 1 ) of the SA cis‐keto and trans‐keto conformers, surrounded by a cluster of other molecules representing the crystalline structure, were optimized by using a QM/QM’ ONIOM approach with and without electronic embedding. The model system consisting of the central salicylidene aniline molecule was treated at the DFT level by using either the B3LYP, PBE0, or the CAM‐B3LYP functional, whereas the real system was treated at the HF level. The CAM‐B3LYP/HF level of theory provides emission energies in good agreement with experiment with differences of −20/−32 nm ( cis‐keto form) and −8/−14 nm ( trans‐keto form), respectively, whereas notably larger differences are obtained using global hybrids. Though such differences on the optical properties arise from the density functional choice, the contribution of the electronic embedding is rather independent of the functional used. This plays in favor of a more general applicability of the present protocol to other crystalline molecular systems. © 2016 Wiley Periodicals, Inc.