A Fast, Convenient, Polarizable Electrostatic Model for Molecular Dynamics.

Area of Science:

• Computational Chemistry
• Molecular Dynamics Simulations
• Physical Chemistry

Background:

• Accurate molecular modeling requires precise electrostatic interactions.
• Existing nonpolarizable force fields often struggle to capture the nuances of electrostatic potentials.
• Development of polarizable force fields is crucial for advancing simulation accuracy.

Purpose of the Study:

• To introduce an efficient polarizable electrostatic model for molecular dynamics (MD) simulations.
• To provide two novel methods, RESP-dPol and AM1-BCC-dPol, for assigning partial charges within a polarizable framework.
• To enable accurate replication of gas-phase quantum mechanical electrostatic potentials.

Main Methods:

• Utilized typed, atom-centered polarizabilities and the fast direct approximation for computational efficiency.
• Developed RESP-dPol as a generalization of the RESP charge model.
• Adapted the AM1-BCC method into AM1-BCC-dPol for polarizable simulations.
• Parametrized the model for molecules containing C, N, O, and H elements.

Main Results:

• Benchmarks showed good agreement with gas-phase dipole moments and molecular polarizabilities.
• The model achieved markedly more accurate static dielectric constants for organic liquids compared to nonpolarizable force fields.
• MD simulations ran efficiently, with only a 3.6-fold increase in speed compared to fixed-charge models.

Conclusions:

• RESP-dPol and AM1-BCC-dPol offer improved accuracy over fixed-charge force fields.
• These methods serve as excellent starting points for developing general, affordable, and transferable polarizable force fields.
• The implemented software integrates with the Open Force Field Initiative, facilitating further development and exploration.