Benchmarks of electronically excited states: basis set effects on CASPT2 results.
Benchmarks of electronically excited states: basis set effects on CASPT2 results.
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电子激发态的基准：基组对 CASPT2 结果的影响。
DOI：
10.1063/1.3499598
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
W. Thiel
中科院分区：
文献类型：
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作者：
Mario R Silva;M. Schreiber;S. Sauer;W. Thiel
使用多态多构型二阶微扰理论 (MS-CASPT2) 和增强相关一致 aug-cc-pVTZ 基组计算 28 种中等尺寸有机基准分子的价激发态的垂直激发能和单电子性质。它们与之前报道的使用较小 TZVP 基础获得的 MS-CASPT2 结果进行了比较。从 TZVP 到 aug-cc-pVTZ 的基组扩展导致垂直激发能发生相当小的和系统性的变化，这些变化通常会稍微减少（单重态平均减少 0.11 eV，三重态平均减少 0.09 eV），而计算的振荡器强度和偶极矩的变化在相对范围内更为明显。 MS-CASPT2 水平上的这些基组效应在定性和定量上与同一组基准分子的耦合簇水平上发现的效应相似。通过用 aug-cc-pVTZ 数据替换 TZVP，对基准分子的 104 个单重态和 63 个三重态激发态的垂直激发能先前提出的理论最佳估计 (TBE-1) 进行了升级，产生了新的参考集 (TBE-2)。密度泛函理论 (DFT) 和半经验方法的性能统计评估导致 TBE-1 和 TBE-2 具有相同的排名和非常相似的定量结果，而 TBE-2 的性能测量稍好一些。在所研究的基于 DFT 的方法中，DFT/MRCI 是最准确的，而具有正交化校正的 OMx 方法在半经验水平上表现最好。
Vertical excitation energies and one-electron properties are computed for the valence excited states of 28 medium-sized organic benchmark molecules using multistate multiconfigurational second-order perturbation theory (MS-CASPT2) and the augmented correlation-consistent aug-cc-pVTZ basis set. They are compared with previously reported MS-CASPT2 results obtained with the smaller TZVP basis. The basis set extension from TZVP to aug-cc-pVTZ causes rather minor and systematic shifts in the vertical excitation energies that are normally slightly reduced (on average by 0.11 eV for the singlets and by 0.09 eV for the triplets), whereas the changes in the calculated oscillator strengths and dipole moments are somewhat more pronounced on a relative scale. These basis set effects at the MS-CASPT2 level are qualitatively and quantitatively similar to those found at the coupled cluster level for the same set of benchmark molecules. The previously proposed theoretical best estimates (TBE-1) for the vertical excitation energies for 104 singlet and 63 triplet excited states of the benchmark molecules are upgraded by replacing TZVP with aug-cc-pVTZ data that yields a new reference set (TBE-2). Statistical evaluations of the performance of density functional theory (DFT) and semiempirical methods lead to the same ranking and very similar quantitative results for TBE-1 and TBE-2, with slightly better performance measures with respect to TBE-2. DFT/MRCI is most accurate among the investigated DFT-based approaches, while the OMx methods with orthogonalization corrections perform best at the semiempirical level.