Ünal Aslı, Bozkaya Uğur
Department of Chemistry, Hacettepe University, Ankara 06800, Turkey.
J Chem Phys. 2024 Sep 21;161(11). doi: 10.1063/5.0223132.
The density-fitted equation-of-motion (EOM) orbital-optimized second-order perturbation theory (DF-EOM-OMP2) method is presented for the first time. In addition, κ-DF-EOM-MP2 and κ-DF-EOM-OMP2 methods are implemented with the addition of κ-regularization. The accuracy of the DF-EOM-OMP2, κ-DF-EOM-MP2, and κ-DF-EOM-OMP2 methods are compared to the density-fitted EOM-MP2 (DF-EOM-MP2), EOM coupled-cluster (CC) singles and doubles (DF-EOM-CCSD), and EOM-CCSD with the triples excitation correction model [EOM-CCSD(fT)] for excitation energies of many closed- and open-shell chemical systems. The excitation energies computed using different test cases and methods were compared to the EOM-CCSD(fT) method and mean absolute errors (MAEs) are presented. The MAE values of closed- and open-shell cases (closed-shell organic chromophores set, open-shell set, peptide radicals set, and radical set) according to the EOM-CCSD(fT) method show that the κ-regularization technique yields highly accurate results for the first excited states. Our results indicate that the κ-DF-EOM-MP2 and κ-DF-EOM-OMP2 methods perform noticeably better than the DF-EOM-MP2 and DF-EOM-OMP2 methods. They approach the EOM-CCSD quality, at a significantly reduced cost, for the computation of excitation energies. Especially, the κ-DF-EOM-MP2 method provides outstanding results for most test cases considered. Overall, we conclude that the κ-versions of DF-EOM-MP2 and DF-EOM-OMP2 emerge as a useful computational tool for the study of excited-state molecular properties.
首次提出了密度拟合运动方程（EOM）轨道优化二阶微扰理论（DF-EOM-OMP2）方法。此外，通过添加κ正则化实现了κ-DF-EOM-MP2和κ-DF-EOM-OMP2方法。将DF-EOM-OMP2、κ-DF-EOM-MP2和κ-DF-EOM-OMP2方法的精度与密度拟合EOM-MP2（DF-EOM-MP2）、EOM耦合簇（CC）单双激发（DF-EOM-CCSD）以及具有三重激发校正模型的EOM-CCSD [EOM-CCSD(fT)]进行比较，用于许多闭壳层和开壳层化学体系的激发能计算。将使用不同测试案例和方法计算得到的激发能与EOM-CCSD(fT)方法进行比较，并给出了平均绝对误差（MAE）。根据EOM-CCSD(fT)方法，闭壳层和开壳层案例（闭壳层有机发色团组、开壳层组、肽自由基组和自由基组）的MAE值表明，κ正则化技术对第一激发态产生了高度准确的结果。我们的结果表明，κ-DF-EOM-MP2和κ-DF-EOM-OMP2方法的性能明显优于DF-EOM-MP2和DF-EOM-OMP2方法。在计算激发能时，它们以显著降低的成本接近EOM-CCSD的质量。特别是，κ-DF-EOM-MP2方法在大多数考虑的测试案例中都提供了出色的结果。总体而言，我们得出结论，DF-EOM-MP2和DF-EOM-OMP2的κ版本成为研究激发态分子性质的有用计算工具。
