用于NEXAFS和XPS的含近似三重激发的EOM-CC方法
EOM-CC Methods with Approximate Triple Excitations for NEXAFS and XPS
AI总结：
本研究评估多种近似EOM-CCSDT方法计算小分子K边芯激发/电离能的表现，发现EOM-CCSD*（结合CVS）精度高且成本仅为分子尺寸六次方级，可低成本实现第一周期原子分子的高精度NEXAFS、XPS谱计算。
摘要：
本文在计算若干小分子的K边芯激发和芯电离能的背景下，评估了对全激发态运动方程耦合簇单双三重激发方法（EOM-CCSDT）的多种迭代和微扰近似。研究发现其中几种方法能很好地精准复现完整EOM-CCSDT的能量，尤其是EOM-CCSD*方法，当采用芯价分离（CVS）近似方案时，其计算量严格随分子尺寸的六次方缩放。此前被用于以高性价比方式纳入三重激发效应的EOM-CCSDR(3)方法，表现却相当差，不过确切原因尚未确定。这些结果表明，对于含第一周期原子的分子，可在仅略高于EOM-CCSD的计算成本下得到非常精准的NEXAFS和XPS谱。
英文摘要：
A number of iterative and perturbative approximations to the full equation-of-motion coupled cluster method with single, double, and triple excitations (EOM-CCSDT) are evaluated in the context of calculating the K-edge core-excitation and core-ionization energies of several small molecules. Several of these methods are found to accurately reproduce the full EOM-CCSDT energies well, in particular the EOM-CCSD* method which, when using the core-valence separation (CVS) ansatz, scales rigorously with the sixth power of molecular size. The EOM-CCSDR(3) method, which has been used previously to include triples effects in a cost-effective manner was found to perform rather poorly, although the precise cause has not been determined. These results highlight that very accurate NEXAFS and XPS spectra for molecules with first-row atoms can be computed at a cost not much larger than that for EOM-CCSD.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
