Application of explicitly localized molecular orbitals to electronic structure calculations

Area of Science:

• Quantum Chemistry
• Computational Chemistry
• Theoretical Chemistry

Background:

• Orbital localization methods are crucial for analyzing electronic correlation.
• Regional localized molecular orbitals (RLMO) offer a fragment-based approach to localization.
• Exploiting electronic correlation locality is key for efficient post-Hartree-Fock calculations.

Purpose of the Study:

• To evaluate the performance of the RLMO representation within second-order local Møller-Plesset (LMP2) perturbation theory.
• To assess the accuracy of the RLMO/LMP2 method for calculating electronic correlation energy.
• To compare RLMO/LMP2 results with 'exact' MP2 and Pipek-Mezey LMP2 methods.

Main Methods:

• Generalization of a previously developed method for localizing molecular orbitals on predefined fragments.
• Application of the RLMO method in conjunction with second-order local Møller-Plesset perturbation theory (LMP2).
• Testing the RLMO/LMP2 approach on model systems: n-pentadecane and trans-retinal.

Main Results:

• The RLMO/MP2 method effectively reduces the correlation space.
• The RLMO/MP2 method successfully reproduces over 99% of the correlation energy.
• The study demonstrates the adequacy of RLMO representation in LMP2 calculations.

Conclusions:

• RLMOs are well-suited for exploiting electronic correlation locality in post-Hartree-Fock calculations.
• The RLMO/LMP2 method provides an accurate and efficient way to compute correlation energy.
• This approach holds promise for large-scale quantum chemistry applications.