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.

Automated summary

A novel energy-based localization procedure for molecular orbitals is presented, utilizing a multiscale framework and partitioning the system into active and inactive fragments. The method maximizes repulsion between fragments to obtain localized molecular orbitals, and has been applied to both conjugated and non-conjugated systems. Comparisons with reference values show the method's potential for reducing computational cost while expanding the application range of high-level electron correlation methods.