TY - JOUR
T1 - Ab initio coupled Hartree-Fock investigation of the static first hyperpolarizability of model all-trans-polymethineimine oligomers of increasing size
AU - Champagne, Benoît
AU - Jacquemin, Denis
AU - André, Jean-Marie
AU - Kirtman, Bernard
PY - 1997/4/24
Y1 - 1997/4/24
N2 - The static first hyperpolarizability tensor of model all-trans-polymethineimine oligomers has been computed ab initio as a function of chain length using the coupled Hartree-Fock method with the 6-31G basis. Careful extrapolations were carried out to obtain reliable infinite polymer values per unit cell. For the most realistic structure the longitudinal component is about 4 times larger than any other and is of the same order of magnitude as in push-pull polyenes. A plot of this component vs chain length exhibits a characteristic "dromedary back" shape. The role of bond alternation and heteroatomicity in determining this shape through their effect on the electronic delocalization and two different types of asymmetry (backbone, chain end) is examined qualitatively as well as quantitatively. It is shown that the correct chain length dependence is not reproduced by the uncoupled Hartree-Fock approximation.
AB - The static first hyperpolarizability tensor of model all-trans-polymethineimine oligomers has been computed ab initio as a function of chain length using the coupled Hartree-Fock method with the 6-31G basis. Careful extrapolations were carried out to obtain reliable infinite polymer values per unit cell. For the most realistic structure the longitudinal component is about 4 times larger than any other and is of the same order of magnitude as in push-pull polyenes. A plot of this component vs chain length exhibits a characteristic "dromedary back" shape. The role of bond alternation and heteroatomicity in determining this shape through their effect on the electronic delocalization and two different types of asymmetry (backbone, chain end) is examined qualitatively as well as quantitatively. It is shown that the correct chain length dependence is not reproduced by the uncoupled Hartree-Fock approximation.
UR - http://www.scopus.com/inward/record.url?scp=0001712763&partnerID=8YFLogxK
M3 - Article
AN - SCOPUS:0001712763
SN - 1089-5639
VL - 101
SP - 3158
EP - 3165
JO - The Journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory
JF - The Journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory
IS - 17
ER -