Roos Björn O, Lindh Roland, Malmqvist Per-Ake, Veryazov Valera, Widmark Per-Olof, Borin Antonio Carlos
Department of Theoretical Chemistry, Chemical Center, PO Box 124, SE-221 00 Lund, Sweden.
J Phys Chem A. 2008 Nov 13;112(45):11431-5. doi: 10.1021/jp803213j. Epub 2008 Oct 18.
New basis sets of the atomic natural orbital (ANO) type have been developed for the lanthanide atoms La-Lu. The ANOs have been obtained from the average density matrix of the ground and lowest excited states of the atom, the positive ions, and the atom in an electric field. Scalar relativistic effects are included through the use of a Douglas-Kroll-Hess Hamiltonian. Multiconfigurational wave functions have been used with dynamic correlation included using second-order perturbation theory (CASSCF/CASPT2). The basis sets are applied in calculations of ionization energies and some excitation energies. Computed ionization energies have an accuracy better than 0.1 eV in most cases. Two molecular applications are included as illustration: the cerium diatom and the LuF3 molecule. In both cases it is shown that 4f orbitals are not involved in the chemical bond in contrast to an earlier claim for the latter molecule.
已为镧系元素原子La - Lu开发了新型原子自然轨道（ANO）类型的基组。这些ANO是从原子、正离子以及处于电场中的原子的基态和最低激发态的平均密度矩阵中获得的。通过使用道格拉斯 - 克罗尔 - 赫斯哈密顿量包含标量相对论效应。多组态波函数已与使用二阶微扰理论（CASSCF/CASPT2）包含的动态相关性一起使用。这些基组应用于电离能和一些激发能的计算。在大多数情况下，计算得到的电离能精度优于0.1 eV。作为示例包含两个分子应用：铈双原子分子和LuF3分子。在这两种情况下都表明，与之前对后一种分子的说法相反，4f轨道不参与化学键。
