Abstract: On the basis of ZINDOprogram, we have designed a program to calculate the nonlinear second-order polarizabilities β_ijk and β_μ according to the SOSequation. The second-order nonlinear optical properties of diazadistyrene derivatives were studied. The calculated results reveal that the introduction of pyrimidine does not influence the transparency but give a rise to large values of β. For the corresponding stilbene derivatives, the effect of the location of pyrimidine on the values of β is greater.

Key words: Diazadistyrene derivatives, Second-order polarizabilities, ZINDO SOS