Geometrical effect on the first hyperpolarizability of thiophene-substituted stilbene derivatives

This paper presents dipole moment (μ), static mean polarizability (α) and mean first hyperpolarizability (β) of thiophene-substituted stilbene derivatives calculated in the framework of density functional theory. The calculations were performed using a finite field approach implemented in the density functional program allchem. All-electron type basis sets optimized for the calculation of the polarizabilities and hyperpolarizabilities using a local exchange-correlation functional were employed. The molecular structures have been fully optimized using the semiempirical program MSINDO. The calculated mean first hyperpolarizability trends are in agreement with the experimental trends obtained from hyper-Rayleigh scattering technique. This work shows that the increased of hyperpolarizability of the studied thiophene-substituted stilbene derivatives is due to a geometrical effect of their trans and cis isomers.