Çaylak Onur, Baumeier Björn
Department of Mathematics and Computer Science, Eindhoven University of Technology, P.O. Box 513, 5600MB Eindhoven, The Netherlands.
Institute for Complex Molecular Systems, Eindhoven University of Technology, P.O. Box 513, 5600MB Eindhoven, The Netherlands.
J Chem Theory Comput. 2021 Feb 9;17(2):879-888. doi: 10.1021/acs.jctc.0c01099. Epub 2021 Jan 5.
We present a benchmark study of gas phase geometry optimizations in the excited states of carbon monoxide, acetone, acrolein, and methylenecyclopropene using many-body Green's functions theory within the approximation and the Bethe-Salpeter equation (BSE) employing numerical gradients. We scrutinize the influence of several typical approximations in the -BSE framework; we used one-shot or eigenvalue self-consistent ev, employing a fully analytic approach or plasmon-pole model for the frequency dependence of the electron self-energy, or performing the BSE step within the Tamm-Dancoff approximation. The obtained geometries are compared to reference results from multireference perturbation theory (CASPT2), variational Monte Carlo (VMC) method, second-order approximate coupled cluster (CC2) method, and time-dependent density-functional theory (TDDFT). We find overall a good agreement of the structural parameters optimized with the -BSE calculations with CASPT2, with an average relative error of around 1% for the and 1.5% for the ev variants based on a PBE0 ground state, respectively, while the other approximations have negligible influence. The relative errors are also smaller than those for CC2 and TDDFT with different functionals and only larger than VMC, indicating that the -BSE method does not only yield excitation energies but also geometries in good agreement with established higher-order wave function methods.
我们展示了一项基准研究，该研究使用近似条件下的多体格林函数理论以及采用数值梯度的贝叶斯 - 萨尔皮特方程（BSE），对一氧化碳、丙酮、丙烯醛和亚甲基环丙烯激发态的气相几何结构优化进行了研究。我们仔细研究了 -BSE 框架中几种典型近似的影响；我们使用单次或本征值自洽的 ev，采用全解析方法或等离子体极点模型来描述电子自能的频率依赖性，或者在塔姆 - 丹科夫近似内执行 BSE 步骤。将得到的几何结构与多参考微扰理论（CASPT2）、变分蒙特卡罗（VMC）方法、二阶近似耦合簇（CC2）方法以及含时密度泛函理论（TDDFT）的参考结果进行比较。我们总体发现，基于 PBE0 基态，用 -BSE 计算优化得到的结构参数与 CASPT2 有很好的一致性，对于 变体平均相对误差约为 1%，对于 ev 变体平均相对误差约为 1.5%，而其他近似的影响可忽略不计。相对误差也小于使用不同泛函的 CC2 和 TDDFT 的相对误差，仅大于 VMC 的相对误差，这表明 -BSE 方法不仅能给出激发能，还能给出与成熟的高阶波函数方法高度一致的几何结构。
