Analytic First-Order Derivatives of (X)MS, XDW, and RMS Variants of the CASPT2 and RASPT2 Methods
Analytic First-Order Derivatives of (X)MS, XDW, and RMS Variants of the CASPT2 and RASPT2 Methods
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CASPT2 和 RASPT2 方法的 (X)MS、XDW 和 RMS 变体的解析一阶导数
DOI：
10.1021/acs.jctc.2c00301
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发表时间：
2022
影响因子：
5.5
通讯作者：
and Roland Lindh
中科院分区：
文献类型：
--
作者：
Yoshio Nishimoto;Stefano Battaglia;and Roland Lindh
状态之间的交叉涉及复杂的电子结构，使得交叉点的准确表征变得困难。在这项研究中，三个完整的活性空间二阶微扰理论（CASPT 2）的变体，以及限制活性空间（RASPT 2）的扩展的解析导数的开发。这些变量适用于定位最小能量圆锥交点。我们的研究结果表明，这三个CASPT 2变体预测定性相似的结果，但最近开发的变体，旋转多态CASPT 2（RMS-CASPT 2），是最不敏感的计算中考虑的状态的数量。我们表明，CASPT 2和参考自洽场计算预测定性不同的能量和键长。
Crossings between states involve complex electronic structures, making the accurate characterization of the crossing point difficult. In this study, the analytic derivatives of three complete active space second-order perturbation theory (CASPT2) variants as well as an extension of the restricted active space (RASPT2) are developed. These variants are applied to locating minimum energy conical intersections. Our results demonstrate that the three CASPT2 variants predict qualitatively similar results, but a recently developed variant, the rotated multistate CASPT2 (RMS-CASPT2), is least sensitive to the number of states considered in the calculation. We demonstrate that CASPT2 and the reference self-consistent field calculations predict qualitatively different energetics and bond lengths.