ADCHα-I population analysis and constrained dipole moment density functional theory in force fields for molecular...

Area of Science:

• Computational Chemistry
• Molecular Modeling
• Quantum Chemistry

Background:

• Accurate charge distributions are crucial for molecular simulations and force fields.
• Existing methods like Hirshfeld (H) and iterative Hirshfeld (H-I) have limitations in capturing charge response.
• Atomic dipole moment corrected Hirshfeld (ADCH) and constrained dipole moment density functional theory (CD-DFT) offer improvements but can be further refined.

Purpose of the Study:

• To introduce a new population analysis method, ADCHα-I, for determining molecular charge distributions.
• To integrate the effects of surrounding molecules in liquids into isolated molecule calculations via dielectric constant.
• To enhance the accuracy of force fields for molecular simulations.

Main Methods:

• Developed the ADCHα-I population analysis interpolating between H and H-I methods using parameter α.
• Combined ADCHα-I with constrained dipole moment density functional theory (CD-DFT).
• Determined electronic density for a dipole moment value that matches the experimental dielectric constant.

Main Results:

• The ADCHα-I method, particularly with α = 1/2, yields charge values intermediate to H and H-I methods.
• This approach incorporates local charge response information absent in ADCH.
• The combination of CD-DFT and ADCHα-I accurately describes charge distributions for force fields.

Conclusions:

• The proposed ADCHα-I population analysis, when coupled with CD-DFT, provides a robust method for generating accurate molecular charge distributions.
• This methodology effectively incorporates environmental effects, improving force field parameters for molecular simulations.
• The findings suggest a significant advancement in computational chemistry for predicting liquid properties.