4-N-甲基苯乙烯砒啶盐衍生物振动超极化率的理论研究

在双谐振子近似下，利用耦合微扰Hartree-Fock方法计算了4-N-甲基苯乙烯砒啶盐衍生物分子的静态振动第一超极化率和红外与拉曼光谱，给出了对静态振动第一超极化率起主导贡献的两种简正振动模式. 研究发现，标题分子的静态振动第一超极化率都比较大，且与静态电子第一超极化率呈较好的线性关系. 首次提出了利用红外与拉曼光谱特征峰标识的振动模来估算振动第一超极化率大小的少模方法. 结果表明，少模方法用于估算振动第一超极化率的大小是可行的.

Theoretical study of molecular vibrational hyperpolarizability of 4-N-methylstilbazonium salt derivatives

Based on double harmonic oscillator (DHO) approximation, the static vibrational first hyperpolarizabilities,and the IR and Raman spectra of 4-N-methylstilbazonium salt derivatives are calculated using coupled perturbed Hartree-Fock (CPHF) approach. Two vibrational normal modes which dominate the contribution to the vibrational first hyperpolarizabilities are obtained. It is found that the static vibrational first hyperpolarizabilities of title molecules are large and show a good linear relationship with their electronic counterparts. For the first time we give an approach of estimating the vibrational first hyperpolarizabilities using a few normal modes identified from IR and Raman spectral peaks, which the name as the few mode approach. The results indicate that this approach is practical in the estimation of the vibrational first hyperpolarizability.