Open AccessSolvent-Induced Shift of the Lowest Singlet π → π* Charge-Transfer Excited State ofp-Nitroaniline in Water: An Application of the TDDFT/EFP1 Method
Author(s) -
Sarom Sok,
Soohaeng Yoo Willow,
Federico Zahariev,
Mark S. Gordon
Publication year - 2011
Publication title -
the journal of physical chemistry a
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.756
H-Index - 235
eISSN - 1520-5215
pISSN - 1089-5639
DOI - 10.1021/jp2045564
Subject(s) - time dependent density functional theory , chemistry , solvation , excited state , singlet state , density functional theory , stokes shift , solvent effects , solvent , molecule , chemical physics , molecular physics , computational chemistry , atomic physics , materials science , physics , organic chemistry , luminescence , optoelectronics
The combined time-dependent density functional theory effective fragment potential method (TDDFT/EFP1) is applied to a study of the solvent-induced shift of the lowest singlet π → π* charge-transfer excited state of p-nitroaniline (pNA) from the gas to the condensed phase in water. Molecular dynamics simulations of pNA with 150 EFP1 water molecules are used to model the condensed-phase and generate a simulated spectrum of the lowest singlet charge-transfer excitation. The TDDFT/EFP1 method successfully reproduces the experimental condensed-phase π → π* vertical excitation energy and solvent-induced red shift of pNA in water. The largest contribution to the red shift comes from Coulomb interactions, between pNA and water, and solute relaxation. The solvent shift contributions reflect the increase in zwitterionic character of pNA upon solvation.
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