Atomic charges for conformationally rich molecules obtained through a modified principal component regression

Area of Science:

• Computational Chemistry
• Molecular Modeling
• Quantum Chemistry

Background:

• Accurately modeling molecular dipole moments is crucial for understanding molecular behavior.
• Conformationally rich molecules present challenges due to their dynamic nature and multiple energy minima.
• Existing methods for atomic charge calculation may struggle with complex molecular systems.

Purpose of the Study:

• To develop a novel method for calculating fixed atomic charges.
• To optimize atomic charges for reproducing molecular dipole moments in conformationally rich molecules.
• To provide a reliable reference for modeling polarization effects.

Main Methods:

• A modified principal component regression model was employed.
• The method utilizes conformer geometries, dipole moments, and atomic polar tensor (APT) charges.
• No adjustable parameters are required, ensuring a robust and generalizable approach.

Main Results:

• The proposed dipole-derived charges accurately reproduce molecular dipole moments across conformers.
• Generated charges are numerically close to APT charges, preserving dipole moment variations from distortions.
• Dipole-derived charges outperformed averaged APT and RESP charges for DNA monomers.

Conclusions:

• The dipole-derived charge method offers a parameter-free approach for accurate charge calculation.
• This method is particularly effective for conformationally rich molecules and DNA monomers.
• Dipole-derived charges show significant potential as a reference for modeling polarization in complex molecular systems.