【摘要】 有效核势(ECP)方法是计算含有过渡金属体系的电子结构及物理性质的有效方法.本文比较了一系列典型的ECP基组对计算含过渡金属体系非线性光学性质精度的影响.分别在HF,MP2和DFT理论水平上对过渡金属元素使用不同的ECP基组,计算了几个过渡金属有机化合物的静态一阶超极化率β0.研究结果表明使用有效核势计算含过渡金属体系时,核电子的选取是提高计算精度的前提,ns和np电子应该和nd电子一同作为价电子处理;对于重原子,必须考虑自旋-轨道耦合相对论效应.经过综合评估,认为使用Stuttgart/Dresden赝势的ECP基组,MHF,在计算含有过渡金属体系非线性光学性质方面是比较好的基组;StuttgartRSC1997和SBKJCVDZ相对而言是较好的基组;基组Lanl2dz,Hay-WadtMB(n+1)和Hay-WadtVDZ(n+1)由于没有考虑自旋-轨道耦合,计算精确度次之;而基组CRENBL和CRENBS计算的偏差要大一些,尤其是CRENBS基组由于价电子选择得太少而导致与实验值的偏差最大.更多还原

【Abstract】 The effective core potential (ECP) approach provides a successful way to calculate the electronic structures of transition metal systems. The performance of several typical ECP basis sets on calculating the nonlinear optical properties of transition metal systems has been evaluated. The static first hyperpolarizabili- ties β0 of some typical organometallic compounds have been studied at the HF, MP2 and DFT levels by us- ing different ECP basis sets for metallic atoms. To calculate properties of transition metal systems accurately, the electrons of ns and np orbitals should act as valence electrons as well as those of nd. Alternatively speaking, the effect of spin-orbit-coupling is uppermost in relativistic effects. By comparison, the ECP basis set, MHF, was good for computing the first hyperpolarizabilities of organometallic systems, and the Stuttgart RSC 1997 and the SBKJC VDZ were relatively good. The Lanl2dz, the Hay-Wadt MB (n+1) and the Hay-Wadt VDZ (n+1) did not apply the spin-orbit-coupling, so their calculating accuracy was a little poor- ish. Whereas the CRENBL and the CRENBS provided larger deviations between the computed and experi- mental values than other ECP basis sets.更多还原