Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, China.
The State Key Laboratory of Physical Chemistry of Solid Surfaces, iChem and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, China.
J Chem Phys. 2019 Nov 21;151(19):194107. doi: 10.1063/1.5123197.
Both the efficiency and capability of the seniority number truncated valence bond (VB) methods are highly improved by using our recently proposed extension of Malmqvist's algorithm for the reciprocal transformation of many-electron bases constructed by nonorthogonal orbitals [Zhou, Chen, and Wu, J. Chem. Phys. 149(4), 044111 (2018)] and by the adoption of the direct technique in solving the generalized eigenvalue problem. Due to the compactness of the wave function that benefited from seniority number restriction, the memory need and computational cost for energy evaluation and orbital optimization in valence bond self-consistent field calculation are largely reduced. The last obstacle in nonorthogonal orbital based ab initio VB calculation is thus removed. Consequently, we can accomplish seniority number truncated VB calculation at the same computational scaling as that of the most general configuration selected multiconfigurational self-consistent field with a memory cost much less than the corresponding complete active space self-consistent field (CASSCF). Test on H string molecules shows that the seniority number truncated VB calculation maintains the majority of static correlation by using a more compact wave function than CASSCF.
通过使用我们最近提出的扩展 Malmqvist 算法，用于由非正交轨道构造的多电子基的倒数变换[Zhou、Chen 和 Wu，J. Chem. Phys. 149(4)，044111 (2018)]，并采用直接技术解决广义特征值问题，提高了老资格截断价键（VB）方法的效率和能力。由于波函数的紧凑性得益于老资格数限制，价键自洽场计算中的能量评估和轨道优化的内存需求和计算成本大大降低。因此，非正交轨道基从头 VB 计算中的最后一个障碍被消除。结果，我们可以在与最一般的组态选择多组态自洽场相同的计算规模上完成老资格截断 VB 计算，而内存成本远低于相应的完全活性空间自洽场（CASSCF）。对 H 串分子的测试表明，通过使用比 CASSCF 更紧凑的波函数，老资格截断 VB 计算保持了大部分静态相关性。
