含噻吩环的新推-拉型多环电光聚合物中间体的三阶非线性光学系数的理论研究

Theoretical Studies of Molecules with Nonlinear Optical Third-order Susceptibilities on Pull-push Multi-cycle Electro-optical Polymer Intermediates Including Thiophene Ring

以 ＩＮＤＯ／ＳＣＩ方法为基础，利用完全态求和（ＳＯＳ）公式，计算了一系列新推－拉型多环电光聚合物中间体的三阶非线性光学系数γ（一ω；ω，－ω，ω）和γ（０；０，０，０），研究了γ与分子骨架、给受取代基和噻吩环数目（共轭分子链长的关系）及其与外场频率的关系，表明在链不十分长时，γ与链长的２．６９次方成正比．

On the basis of INDO/SCI method, using sum-over-states(SOS) formula, the nonlinear thirdorder optical susceptibilities γ(-ω;ω,-ω,ω) and γ(0; 0, 0, 0) of a series of novel pull-push electro- optical polymer intermediates have been calculated. The effects of the molecular backbone, donor substituents, accepted substituents, the number of thiophene-rings (namely the conjugated molecular length dependence) and the frequency of external field on γ have been studied. When the molecular chain is not too long, γ(0; 0, 0, 0) varies as the 2. 69 power of length.