Theoretical Calculation of Core-Excited States along Dissociative Pathways beyond Second-Order Perturbation Theory
Theoretical Calculation of Core-Excited States along Dissociative Pathways beyond Second-Order Perturbation Theory
复制标题
超越二阶微扰理论的沿着解离路径的核心激发态的理论计算
DOI：
10.1021/acs.jctc.1c00884
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发表时间：
2022
影响因子：
5.5
通讯作者：
Evangelista, Francesco A.
中科院分区：
文献类型：
--
作者：
Huang, Meng;Li, Chenyang;Evangelista, Francesco A.
我们将多参考驱动相似性重正化 (MR-DSRG) 方法扩展到计算核激发态，将其与轨道弛豫和静态电子相关效应的 GASSCF 处理相结合。我们考虑在微扰理论水平上截断动态相关性的 MR-DSRG 处理 (DSRG-MRPT2/3) 和一体和二体算子的迭代线性化近似 [MR-LDSRG(2)] 与标量相对论效应的无自旋精确二分量 (X2C) 单电子处理相结合。该方法在包含第一行元素（C、N 和 O）的 5 个闭壳层和开壳层双原子分子的一系列 16 个核激发态上进行了校准和测试。所有 GASSCF-MR-DSRG 理论均与实验绝热跃迁能量高度一致，平均绝对误差范围在 0.17 至 0.35 eV 之间，即使对于具有挑战性的 N2+ 分子部分双激发态也是如此。通过使用全势能扫描获得的所有这些跃迁的振动结构显示，DSRG-MRPT2 的平均绝对误差低至 25 meV，DSRG-MRPT3 和 MR-LDSRG (2) 的平均绝对误差低至 12/13 meV。我们通常发现，微扰理论中超越二阶水平的动力学相关性处理可以提高势能面的准确性，特别是在键解离区域。
We extend the multireference driven similarity renormalization (MR-DSRG) method to compute core-excited states by combining it with a GASSCF treatment of orbital relaxation and static electron correlation effects. We consider MR-DSRG treatments of dynamical correlation truncated at the level of perturbation theory (DSRG-MRPT2/3) and iterative linearized approximations with one- and two-body operators [MR-LDSRG(2)] in combination with a spin-free exact-two-component (X2C) one-electron treatment of scalar relativistic effects. This approach is calibrated and tested on a series of 16 core-excited states of five closed- and open-shell diatomic molecules containing first-row elements (C, N, and O). All GASSCF-MR-DSRG theories show excellent agreement with experimental adiabatic transitions energies, with mean absolute errors ranging between 0.17 and 0.35 eV, even for the challenging partially doubly excited states of the N2+molecule. The vibrational structure of all these transitions, obtained from using a full potential energy scan, shows a mean absolute error as low as 25 meV for DSRG-MRPT2 and 12/13 meV for DSRG-MRPT3 and MR-LDSRG(2). We generally find that a treatment of dynamical correlation that goes beyond the second-order level in perturbation theory improves the accuracy of the potential energy surface, especially in the bond-dissociation region.