Department of Chemistry and Cherry Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, USA.
J Chem Phys. 2017 Aug 21;147(7):074107. doi: 10.1063/1.4997480.
We propose an economical state-specific approach to evaluate electronic excitation energies based on the driven similarity renormalization group truncated to second order (DSRG-PT2). Starting from a closed-shell Hartree-Fock wave function, a model space is constructed that includes all single or single and double excitations within a given set of active orbitals. The resulting VCIS-DSRG-PT2 and VCISD-DSRG-PT2 methods are introduced and benchmarked on a set of 28 organic molecules [M. Schreiber et al., J. Chem. Phys. 128, 134110 (2008)]. Taking CC3 results as reference values, mean absolute deviations of 0.32 and 0.22 eV are observed for VCIS-DSRG-PT2 and VCISD-DSRG-PT2 excitation energies, respectively. Overall, VCIS-DSRG-PT2 yields results with accuracy comparable to those from time-dependent density functional theory using the B3LYP functional, while VCISD-DSRG-PT2 gives excitation energies comparable to those from equation-of-motion coupled cluster with singles and doubles.
我们提出了一种基于驱动相似重整化群截断到二阶（DSRG-PT2）的经济态特定方法来评估电子激发能。从闭壳层 Hartree-Fock 波函数出发，构建了一个模型空间，其中包括给定活性轨道内的所有单或单和双激发。引入了 VCIS-DSRG-PT2 和 VCISD-DSRG-PT2 方法，并在 28 个有机分子的数据集上进行了基准测试[M. Schreiber 等人，J. Chem. Phys. 128, 134110 (2008)]。以 CC3 结果作为参考值，VCIS-DSRG-PT2 和 VCISD-DSRG-PT2 激发能的平均绝对偏差分别为 0.32 和 0.22 eV。总的来说，VCIS-DSRG-PT2 的结果与使用 B3LYP 函数的含时密度泛函理论的结果具有相当的准确性，而 VCISD-DSRG-PT2 的激发能与单和双电子运动方程耦合簇的结果相当。
