论文标题
SOICI和ICISO：以两种方式将迭代构型相互作用与自旋轨道耦合相结合
SOiCI and iCISO: Combining iterative configuration interaction with spin-orbit coupling in two ways
论文作者
论文摘要
具有近相关性电子系统的近液体ICIPT2方法，源于迭代构型相互作用（ICI，完整CI的精确求解器）与用于静态相关性和二阶扰动理论（PT2）的配置选择的组合，用于动态相关性。 In the spirit of spin separation, relativistic effects are treated in two steps: scalar relativity is treated by the infinite-order, spin-free part of the exact two-component (X2C) relativistic Hamiltonian, whereas spin-orbit coupling (SOC) is treated by the first-order, Douglas-Kroll-Hess-like SOC operator derived from the same X2C Hamiltonian.考虑了ICIPT2与SOC的两种可能组合，即SOICI和ICISO。前者在平等的基础上对待SOC和电子相关性，而后者则以状态相互作用的精神来对待SOC，通过在少数相关的标量状态下构建和对角线对对角线构建和对角线。双组和时间反向对称性都合并为简化计算。试点应用显示，SOICI对于重原子的自旋轨道裂片（SOS）非常准确，而计算上非常便宜的ICISO可以安全地应用于光原子的SOS，甚至在SOC在很大程度上被配体田淬灭时含有重原子的系统。
The near-exact iCIPT2 approach for strongly correlated systems of electrons, which stems from the combination of iterative configuration interaction (iCI, an exact solver of full CI) with configuration selection for static correlation and second-order perturbation theory (PT2) for dynamic correlation, is extended to the relativistic domain. In the spirit of spin separation, relativistic effects are treated in two steps: scalar relativity is treated by the infinite-order, spin-free part of the exact two-component (X2C) relativistic Hamiltonian, whereas spin-orbit coupling (SOC) is treated by the first-order, Douglas-Kroll-Hess-like SOC operator derived from the same X2C Hamiltonian. Two possible combinations of iCIPT2 with SOC are considered, i.e., SOiCI and iCISO. The former treats SOC and electron correlation on an equal footing, whereas the latter treats SOC in the spirit of state interaction, by constructing and diagonalizing an effective spin-orbit Hamiltonian matrix in a small number of correlated scalar states. Both double group and time reversal symmetries are incorporated to simplify the computation. Pilot applications reveal that SOiCI is very accurate for the spin-orbit splitting (SOS) of heavy atoms, whereas the computationally very cheap iCISO can safely be applied to the SOS of light atoms and even of systems containing heavy atoms when SOC is largely quenched by ligand fields.
