Physical Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008, India.
J Chem Phys. 2013 Aug 21;139(7):074108. doi: 10.1063/1.4817943.
In this paper, we present a formulation based on Lagrange multiplier approach for efficient evaluation of excited state energy derivatives in Fock space coupled cluster theory within the intermediate Hamiltonian framework. The formulation is applied to derive the explicit generic expressions up to second order energy derivatives for [1, 1] sector of Fock space with singles and doubles approximation. Its advantage, efficiency, and interconnection in comparison to the Lagrange multiplier approach in traditional formulation of Fock space, which is built on the concept of Bloch equation based effective Hamiltonian, has been discussed. Computational strategy for their implementation has also been discussed in some detail.
在本文中，我们提出了一种基于拉格朗日乘子方法的公式，用于在中间哈密顿量框架内有效地评估福克空间耦合簇理论中的激发态能量导数。该公式被应用于推导具有单重和双重近似的福克空间[1,1]扇区的二阶能量导数的显式通用表达式。与基于有效哈密顿量的布洛赫方程概念构建的传统福克空间表述中的拉格朗日乘子方法相比，我们讨论了这种方法的优势、效率和相互联系。我们还详细讨论了它们的实现的计算策略。
