Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada.
J Chem Phys. 2010 Feb 21;132(7):074102. doi: 10.1063/1.3297887.
Careful spin-orbit multireference studies were carried out for the late p-block elements Tl, Pb, Bi, Po, At, and Rn and their hydrides using the model core potentials developed in the present work. The model core potentials were designed to treat the scalar-relativistic and spin-orbit coupling effects at the Douglas-Kroll level. The variational stability of the spin-orbit coupling operator was discussed in terms of the relativistic kinematic operators and depicted graphically. A detailed analysis of the spin-orbit multireference dissociation curves of the 6p element hydrides as well as of their atomic spectra allowed to establish the accuracy of the model core potentials with respect to all-electron calculations to be within several mA for r(e), meV (ceV) for D(e) at the correlation level of configuration interaction (multireference perturbation theory), 30 cm(-1) for omega(e), and about 350 cm(-1) for the low-lying atomic and molecular term and level energies. These values are expected to be the maximum error limits for the model core potentials of all the np-block elements (n=2-6). Furthermore, a good agreement with experiment requires that many terms be coupled in the spin-orbit coupling calculations. A timing study of Tl and TlH computations indicates that the model core potentials lead to 20-fold (6-fold) speedup at the level of configuration interaction (multireference perturbation theory) calculations.
使用本工作中发展的模型芯势，对 p 区后元素 Tl、Pb、Bi、Po、At 和 Rn 及其氢化物进行了仔细的自旋-轨道多参考研究。模型芯势旨在在 Douglas-Kroll 水平上处理标量相对论和自旋-轨道耦合效应。自旋-轨道耦合算符的变分稳定性根据相对论运动算子进行了讨论，并以图形方式表示。详细分析了 6p 元素氢化物的自旋-轨道多参考离解曲线及其原子光谱，从而确定了模型芯势相对于全电子计算的准确性，在组态相互作用（多参考微扰理论）的相关水平上，对于 r(e)、meV（ceV）的 D(e) 约为几 mA，对于 ω(e) 约为 30 cm(-1)，对于低能原子和分子项和能级能量约为 350 cm(-1)。这些值预计是所有 np 区元素（n=2-6）的模型芯势的最大误差极限。此外，与实验的良好一致性要求在自旋-轨道耦合计算中耦合许多项。Tl 和 TlH 计算的时间研究表明，模型芯势在组态相互作用（多参考微扰理论）计算水平上可实现 20 倍（6 倍）的加速。
