MCDHF/DC+B-adjusted pseudopotentials for lanthanides and quantum chemical investigations of lanthanide compounds with unusual electronic structure

基于有限核Dirac-Hartree-Fock的自洽处理和Breit相互作用低频极限的微扰处理，从多组态Dirac-Hartree-Fock参考数据推导出镧系元素La（Z=57）至Lu（Z=71）的相对论能量一致的小核（28个核电子）从头算赝势。我们的目标是要达到一个精度优于0.01 eV的各种配置的总能量范围从中性原子到高度带电的离子与空穴在半核心轨道4s，4p，4d，5s和5 p。一般收缩的原子自然轨道基组，为一个和两个组件的计算，高达四重zeta质量将被导出。赝势将在原子以及分子中校准（例如，选择的一氧化物、一氧化物和一氟化物）与相应的全电子从头算参考数据以及实验数据（如果有的话）的相关计算。赝势将被应用于研究具有不寻常成键情况的镧系元素系统，例如，夹心化合物铈双（并环戊二烯）、铈双（酞菁）和铈三（环戊二烯基）阳离子和双原子一氧化镱。在第一种情况下，将研究Ce的氧化态。我们将检验该体系是否具有类似于铈双的Ce（3+）Kondo型开壳层单重态在第二种情况下，将检查4f壳层中具有13和14个电子的Yb子构型之间的构型混合是否导致0+基态的不寻常的光谱常数，表现出Yb（2+）4f 13 6s 1 O（2-）的典型键长和Yb（2+）4f 14 O（2-）的典型振动频率。

Relativistic energy-consistent small-core (28 core electrons) ab initio pseudopotentials will be derived for the lanthanide elements La (Z=57) to Lu (Z=71) from multi-configuration Dirac-Hartree-Fock reference data based on the self-consistent treatment of the finite nucleus Dirac-Coulomb Hamiltonian and a perturbative treatment of the low-frequency limit of the Breit interaction. The goal is to reach an accuracy of better than 0.01 eV for the total energies of various configurations ranging from the neutral atom to highly charged ions with holes in the semi-core orbitals 4s, 4p, 4d, 5s and 5p. Generally contracted atomic natural orbital basis sets, for one- and two-component calculations, with up to quadruple-zeta quality will be derived. The pseudopotentials will be calibrated in atomic as well as molecular (e.g., selected monohydrides, monoxides, and monofluorides) correlated calculations against corresponding all-electron ab initio reference data as well as against experimental data if available.The pseudopotentials will be applied to study lanthanide systems with unusual bonding situations, e.g., the sandwich compounds cerium bis(pentalene), cerium bis(phthalocyanine) and cerium tris(cyclopentadienly) cation and diatomic ytterbium monoxide. In the first case the oxidation state of Ce will be investigated. It will be checked if the system has a similar Ce(3+) Kondo-type open-shell singulet ground state as cerium bis(cyclooctatetraene), cerocene.In the second case it will be examinated if the configurational mixing between Yb subconfigurations with 13 and 14 electrons in the 4f shell leads to the unusual spectroscopic constants of the 0+ ground state, exhibiting a bond length typical for Yb(2+) 4f13 6s1 O(2-) and a vibrational frequency typical for Yb(2+) 4f14 O(2-).