Kállay Mihály, Gauss Jürgen
Institut für Physikalische Chemie, Universität Mainz, D-55099 Mainz, Germany.
J Chem Phys. 2004 Nov 15;121(19):9257-69. doi: 10.1063/1.1805494.
Using string-based algorithms excitation energies and analytic first derivatives for excited states have been implemented for general coupled-cluster (CC) models within CC linear-response (LR) theory which is equivalent to the equation-of-motion (EOM) CC approach for these quantities. Transition moments between the ground and excited states are also considered in the framework of linear-response theory. The presented procedures are applicable to both single-reference-type and multireference-type CC wave functions independently of the excitation manifold constituting the cluster operator and the space in which the effective Hamiltonian is diagonalized. The performance of different LR-CC/EOM-CC and configuration-interaction approaches for excited states is compared. The effect of higher excitations on excited-state properties is demonstrated in benchmark calculations for NH(2) and NH(3). As a first application, the stationary points of the S(1) surface of acetylene are characterized by high-accuracy calculations.
利用基于字符串的算法，在耦合簇（CC）线性响应（LR）理论框架内，针对一般耦合簇模型实现了激发态的激发能和解析一阶导数，该理论对于这些量等同于运动方程（EOM）耦合簇方法。基态与激发态之间的跃迁矩也在线性响应理论框架内进行了考虑。所提出的程序适用于单参考型和多参考型CC波函数，与构成簇算符的激发流形以及有效哈密顿量对角化所在的空间无关。比较了不同的LR-CC/EOM-CC和组态相互作用方法对激发态的性能。在NH(2)和NH(3)的基准计算中展示了高阶激发对激发态性质的影响。作为首次应用，通过高精度计算表征了乙炔S(1)表面的驻点。
