Polarizable empirical force field for aromatic compounds based on the classical drude oscillator

Area of Science:

• Computational Chemistry
• Molecular Dynamics
• Physical Chemistry

Background:

• Accurate molecular simulations require reliable force fields.
• Existing force fields may not adequately represent aromatic compounds like benzene and toluene.
• Polarizable force fields, such as CHARMM based on the classical Drude oscillator, offer improved accuracy.

Purpose of the Study:

• To extend the polarizable CHARMM force field to aromatic compounds benzene and toluene.
• To optimize and validate new parameters against quantum mechanical and experimental data.
• To investigate the structural properties of liquid benzene, toluene, and their aqueous solutions.

Main Methods:

• Parameter optimization using ab initio quantum mechanical calculations.
• Validation against experimental data including heats of vaporization, diffusion constants, and heat capacities.
• Molecular dynamics simulations of pure liquids and solutions.

Main Results:

• Developed and optimized a new parameter set for benzene and toluene within the CHARMM force field.
• Achieved excellent agreement between computed and experimental data for various physical properties.
• Demonstrated accurate prediction of liquid structures and the total distribution function for benzene.

Conclusions:

• The extended CHARMM force field provides accurate descriptions of benzene and toluene.
• The new parameters enable reliable molecular simulations of these aromatic systems and their interactions with water.
• This work advances the capability of classical Drude oscillator-based force fields for aromatic compounds.