Development of reactive force fields using ab initio molecular dynamics simulation minimally biased to experimental...

Area of Science:

• Computational Chemistry
• Chemical Physics
• Materials Science

Background:

• Quantum mechanical electronic structure data is essential for accurately simulating chemical processes like proton hopping in water.
• Standard ab initio molecular dynamics (AIMD) methods struggle to accurately predict water structure, limiting their use in developing accurate force fields.
• Proton hopping involves complex chemical and hydrogen bond rearrangements, necessitating advanced simulation techniques.

Purpose of the Study:

• To develop novel multiscale reactive molecular dynamics (MS-RMD) force fields for simulating proton hopping in water.
• To utilize a minimally biased AIMD approach, incorporating experimental data via relative entropy minimization for force field parameterization.
• To present and evaluate two new MS-RMD models: one with harmonic water and another with anharmonic water.

Main Methods:

• Employed a recently developed method that minimally biases AIMD simulations towards experimental data.
• Utilized relative entropy minimization to parameterize novel MS-RMD force fields.
• Developed two MS-RMD models: one with harmonic internal vibrations for water and another with anharmonic water.

Main Results:

• The newly developed MS-RMD models accurately reproduce the solvation structure of the hydrated excess proton, matching target AIMD data.
• The model employing anharmonic water demonstrated increased proton hopping compared to the harmonic model.
• The anharmonic water model resulted in a higher proton diffusion constant.

Conclusions:

• Novel MS-RMD force fields, parameterized with minimally biased AIMD and experimental data, can accurately capture the physics of proton hopping in water.
• The inclusion of anharmonicity in water models within MS-RMD simulations enhances proton mobility and diffusion.
• These findings offer improved computational tools for studying proton transport phenomena in aqueous systems.