【摘要】 在RHF/STO-3G和RHF/6-31G水平上优化聚乙炔链,计算了聚乙炔链的轴向线性极化率αzz和二阶超极化率γzzzz,最多计算到27个—C≡C—结构单元,利用不同电场下分子的E、μ、α、β获得了RHF水平的稳定可靠的γzzzz;用不同电场下的能量得到了MP2/6-31G水平的γ值,计算到19个结构单元.在此基础上根据选定的目标函数、拟合函数和拟合数据范围,外推出可信的超极化率的极限值,讨论了优化水平和基组对α和γ计算值的影响.更多还原

【Abstract】 Ab initio calculations are reported for the static longitudinal polarizability α_zz and the second hyperpolarizability γ_zzzz of the polyyne chain at different levels of approximation of including geometries,basis sets,and electron correlation.The geometries of all studed molecules are optimized at RHF/STO-3G or RHF/6-31G levels.The largest molecule calculated is H—（C≡C）₂₇—H for RHF and H—（C≡C）₁₉—H for MP2.The values per C≡C unit are accurately extrapolated to the infinite chain limit at RHF and MP2 levels.The influences of optimized levels,basis sets and electron correlation on α and γ are discussed.更多还原