13顶点金属碳硼烷结构和非线性光学性质的DFT研究

Density Functional Theory Study on Structure and Nonlinear Optical Properties of 13-Vertex Metallacarborane

采用量子化学密度泛函理论(DFT)B3LYP/6-31G(d)方法,对4,1,6-MC2B10H1213顶点金属碳硼烷几何构型进行优化,结合有限场(FF)方法计算了它们的极化率和二阶非线性光学(NLO)系数.结果表明,十个13顶点金属碳硼烷分子中1a～6a的二阶NLO系数与其构型纵向扩张呈现相同的规律.分子的前线分子轨道能级差越小,其二阶NLO系数越大.对于不同自旋态的同种金属碳硼烷分子,其偶极矩值为高自旋态大于相应的低自旋态,极化率和二阶NLO系数与自旋多重度没有一致的对应规律,自旋多重度对NLO性质影响不大.

Density functional theory （DFT） B3LYP method based on the 6-31G（d） level were employed to optimize the structures of 13-vertex metallacarborane 4,1,6-MC2B10H12.The polarizability and second-order nonlinear optical （NLO） coefficients were calculated by means of finite-field （FF） method.The results show that the second-order NLO coefficients of 1a～6a molecules have identical change with their configurations.In all metallacarboranes,the smaller the frontier molecular orbital energy gap is,the larger the second-order NLO coefficient is.For the homogeneous metallacarborane of different spin states,the dipole moments of high-spin state are larger than that of low-spin state,however,the polarizability and second-order NLO coefficient have not direct relationships with spin multiplicity.Therefore,the spin state has a little influence on NLO properties.