Energy-Based Molecular Orbital Localization in a Specific Spatial Region

We present a novel energy-based localization procedure able to localize molecular orbitals into predefined spatial regions. The method is defined in a multiscale framework based on the multilevel Hartree–Fock approach. In particular, the system is partitioned into active and inactive fragments. The localized molecular orbitals are obtained maximizing the repulsion between the two fragments. The method is applied to several cases including both conjugated and non-conjugated systems. Our multiscale approach is compared with reference values for both ground-state properties, such as dipole moments, and local excitation energies. The proposed approach is useful to extend the application range of high-level electron correlation methods. In fact, the reduced number of molecular orbitals can lead to a large reduction in the computational cost of correlated calculations.本报告提出了一种新颖的基于能量的定位程序，该程序能够将分子轨道定位到预定义的空间区域。此方法基于多尺度框架，采用多层次哈特里-福克方法进行定义。具体而言，系统被划分为活跃部分和非活跃部分。通过最大化两个部分之间的排斥力，获得局部化的分子轨道。该方法被应用于包括共轭和非共轭系统在内的多个案例。我们的多尺度方法与参考值进行了比较，包括基态性质，如偶极矩，以及局部激发能。所提出的方法有助于扩展高级电子关联方法的适用范围。实际上，分子轨道数量的减少可以显著降低关联计算的计算成本。