A dependable description of the frontier orbitals around the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) is essential for the theoretical elucidation of exciton and charge-transfer dynamics in molecular systems. In this study, an efficient scheme for constructing molecular orbitals (MOs) of large molecular systems is proposed within the framework of the fragment molecular orbital (FMO) method. In contrast to the previously proposed energy-based methodology, called the linear combination of molecular orbitals of FMO (FMO-LCMO), the present scheme employs the density matrices of monomer and dimer MOs of fragments to select the monomer MOs as the basis set for constructing the Hamiltonian matrix of the total system. The accuracy and computational cost of the proposed scheme are assessed in comparison with those of the conventional energy-based methods for three model systems of DNA stacked base pairs, pseudo-glycine pentamer, and water clusters, thus demonstrating its efficiency in terms of data compression.

中文翻译：

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基于密度矩阵的片段分子轨道线性组合的基础选择方案

对最高占据分子轨道（HOMO）和最低未占据分子轨道（LUMO）周围的前沿轨道的可靠描述对于分子系统中激子和电荷转移动力学的理论阐明是必不可少的。在这项研究中，在碎片分子轨道（FMO）方法的框架内，提出了一种构建大分子系统分子轨道（MOs）的有效方案。与先前提出的基于能量的方法（称为FMO分子轨道的线性组合（FMO-LCMO））不同，本方案采用单体的密度矩阵和片段的二聚体MOs选择单体MOs作为基础构造整个系统的哈密顿矩阵。