Charge distributions for molecular dynamics simulations from self-consistent polarization method.

Area of Science:

• Computational chemistry
• Molecular modeling
• Physical chemistry

Background:

• Partial atomic charges are essential parameters in molecular force fields.
• Current methods often rely on simplified population schemes in quantum chemical calculations.
• Accurate charge derivation is critical for predicting molecular behavior.

Purpose of the Study:

• To propose a novel polarization-consistent scheme for deriving molecular charge distributions.
• To investigate the impact of environmental effects on partial atomic charges.
• To establish reliable computational protocols for charge calculations.

Main Methods:

• Employed various computational schemes: Hartree-Fock (HF), Møller-Plesset perturbation theory (MP2), and density functional theory (DFT) including B3LYP and M026X.
• Utilized a range of basis sets from cc-pvdz to cc-pv6z.
• Applied electrostatic potential-derived charge methods such as KS, CHELP, CHELPG, and HLY.
• Explicitly modeled the solvent environment by including multiple solvation shells.

Main Results:

• Demonstrated the significant and indispensable role of environmental effects in charge distribution calculations.
• Showed that including the second solvation shell is necessary for achieving charge convergence.
• Identified induction and dispersion effects as major contributors to charge corrections.
• The B3LYP/cc-pvqz level of theory with a self-consistent polarization scheme is recommended.

Conclusions:

• Environmental effects, particularly solvation, are critical for accurate partial atomic charge calculations.
• A comprehensive approach including multiple solvation shells and specific computational methods is required.
• The proposed polarization-consistent scheme offers a robust method for deriving reliable force field parameters.