Torsional effects on excitation energies of thiophene derivatives induced by beta-substituents: comparison between time-dependent density functional theory and approximated coupled cluster approaches.
The influence of methyl or phenyl substitution in beta-position of dioxygenated terthiophene and diphenylthiophene on the optical properties is investigated by first-principles calculations. We compare the approximated singles and doubles coupled cluster (CC2) approach with time-dependent density functional theory methods. CC2 reproduces experimental excitation energies with an accuracy of 0.1 eV. We find that the different substituents modify the inter-ring torsional angle which in turn strongly influences the excitation energies. The steric contribution to the excitation energies have been separated from the total substituent effects.
Piacenza
M
M
National Nanotechnology Laboratory of INFM, Distretto Tecnologico ISUFI, Università degli Studi di Lecce, Via per Arnesano, I-73100 Lecce, Italy. mpiacenza@web.de
Della Sala
F
F
Fabiano
E
E
Maiolo
T
T
Gigli
G
G
D016000:Cluster Analysis; D004583:Electrons; D008958:Models, Molecular; D008968:Molecular Conformation; D013876:Thiophenes / Q000737:chemistry*; D013997:Time Factors
D013876:Thiophenes