Hapka Michał, Pernal Katarzyna, Jensen Hans Jørgen Aa
Faculty of Chemistry, University of Warsaw, ul. L. Pasteura 1, 02-093 Warsaw, Poland.
Institute of Physics, Lodz University of Technology, ul. Wolczanska 217/221, 93-005 Lodz, Poland.
J Chem Phys. 2022 May 7;156(17):174102. doi: 10.1063/5.0082155.
We present an implementation of time-dependent linear-response equations for strongly orthogonal geminal wave function models: the time-dependent generalized valence bond (TD-GVB) perfect-pairing theory and the antisymmetrized product of strongly orthogonal geminals. The geminal wave functions are optimized using a restricted-step second-order algorithm suitable for handling many geminals, and the linear-response equations are solved in an efficient way using a direct iterative approach. The wave function optimization algorithm features an original scheme to create initial orbitals for the geminal functions in a black-box fashion. The implementation is employed to examine the accuracy of the geminal linear response for singlet excitation energies of small and medium-sized molecules. In systems dominated by dynamic correlation, geminal models constitute only a minor improvement with respect to time-dependent Hartree-Fock. Compared to the linear-response complete active space self-consistent field, TD-GVB either misses or gives large errors for states dominated by double excitations.
含时广义价键（TD - GVB）完美配对理论以及强正交双电子的反对称积。使用适用于处理多个双电子的受限步二阶算法对双电子波函数进行优化，并采用直接迭代方法高效求解线性响应方程。波函数优化算法具有一种以黑箱方式为双电子函数创建初始轨道的原始方案。该实现用于检验双电子线性响应对中小分子单重激发能的准确性。在由动态关联主导的系统中，双电子模型相对于含时Hartree - Fock仅构成微小改进。与线性响应完全活性空间自洽场相比，对于由双激发主导的态，TD - GVB要么遗漏要么给出较大误差。
