Theoretical study on the device of molecules with third-order NLO susceptibility on a series of multi-substituent babituric acid and its derivatives

On the basis of ZINDO, the program for calculating the third order NLO susc eptibility gamma(ijkl) was devised according to the sum-over-state expressi on. The structure, electron spectra, gamma(-omega; -omega,omega,omega), and gamma(0;0, 0,0) of a series of multi-substituent babituric acid derivative molecules were studied. The influence of donor pi-conjugated bridge, accep tor, D-pi-A, D-B, D-A-D structure on the gamma was examined. The conclusion is that, 1. the gamma values of oxo-babituric acid higher than thio-babitu ric acid. 2. Thermal stability and the values of gamma of the aryl donor su bstituent enlarge as compared with the alkyl donor substituent. At last, we designed excellent NLO materials which have practical applications with bi gger gamma and good thermal stability.