Department of Chemistry, Yale University, 225 Prospect St., New Haven, Connecticut 06511, USA.
J Chem Phys. 2010 Feb 28;132(8):084102. doi: 10.1063/1.3314221.
We present a study of excitation energies in solution at the equation of motion coupled cluster singles and doubles (EOM-CCSD) level of theory. The solvent effect is introduced with a state specific polarizable continuum model (PCM), where the solute-solvent interaction is specific for the state of interest. Three definitions of the excited state one-particle density matrix (1PDM) are tested in order to gain information for the development of an integrated EOM-CCSD/PCM method. The calculations show the accuracy of this approach for the computation of such property in solution. Solvent shifts between nonpolar and polar solvents are in good agreement with experiment for the test cases. The completely unrelaxed 1PDM is shown to be a balanced choice between computational effort and accuracy for vertical excitation energies, whereas the response of the ground state CCSD amplitudes and of the molecular orbitals is important for other properties, as for instance the dipole moment.
我们在运动方程耦合簇单双（EOM-CCSD）理论水平上研究了溶液中的激发能。采用状态特异极化连续体模型（PCM）引入溶剂效应，其中溶质-溶剂相互作用是针对感兴趣的状态特定的。为了开发集成的 EOM-CCSD/PCM 方法，我们测试了三种激发态单粒子密度矩阵（1PDM）的定义，以获取有关该方法的信息。计算结果表明，该方法在计算溶液中的此类性质时具有较高的准确性。对于测试案例，非极性和极性溶剂之间的溶剂位移与实验结果吻合良好。对于垂直激发能，完全不弛豫的 1PDM 在计算工作量和准确性之间是一个平衡的选择，而对于其他性质，例如偶极矩，基态 CCSD 幅度和分子轨道的响应则很重要。
