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A Simple Effective Δ SCF Method for Computing Optical Gaps in Organic Chromophores
Author(s) -
Roy Raj,
Ghosal Abhisek,
Roy Amlan K.
Publication year - 2021
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.202100692
Subject(s) - excited state , time dependent density functional theory , chromophore , open shell , density functional theory , excitation , singlet state , simple (philosophy) , chemistry , computational chemistry , ground state , band gap , molecular physics , statistical physics , materials science , quantum mechanics , physics , philosophy , epistemology
Photoluminescence effects in organic chromophores are of significant importance and requires precise description of low lying excited states. In this communication, we put forward an alternative time‐independent DFT scheme for computing lowest single‐particle excitation energy, especially for singlet excited state. This adopts a recently developed “virial“‐theorem based model of singlet‐triplet splitting which requires a DFT calculation on closed shell ground state and a restricted open‐shell triplet excited state, followed by a simple 2 e -integral evaluation. This produces vertical excitation energies in small molecules, linear and non‐linear polycyclic aromatic hydrocarbon and organic dyes in comparable accuracy to the TDDFT. We also explore the functional dependency of present method with three different functionals (B3LYP, wB97X and CAM‐B3LYP) for polyenes and linear acenes. A systematic comparison with literature value illustrates the validity and usefulness of the present scheme in determining optical gap with fair computational cost.