TAMie Force Field for Alkanethiols: Multifidelity Gaussian Processes for Dealing with Scarce Experimental Data

Area of Science:

• Chemical Physics
• Materials Science
• Computational Chemistry

Background:

• Accurate molecular modeling of alkanethiols is crucial for understanding their physical properties.
• Existing models often lack transferability and accuracy across different alkanethiols and conditions.
• The transferable anisotropic Mie potential (TAMie) offers a promising framework for molecular simulations.

Purpose of the Study:

• To extend the transferable anisotropic Mie potential (TAMie) to accurately model alkanethiols.
• To optimize TAMie force field parameters using an analytic equation of state and Gaussian process approach.
• To validate the model's predictions for pure alkanethiols and their binary mixtures with alkanes.

Main Methods:

• Optimization of TAMie force field parameters using an analytic equation of state as a surrogate model.
• Supplementation with a linear multifidelity Gaussian process approach to bridge temperature gaps in experimental data.
• Minimization of deviations between calculated and experimental vapor pressures and liquid densities for C1-C5 thiols.
• Validation of transferability to higher alkanethiols (C6, C8) and prediction of shear viscosity.
• Study of phase behavior in binary mixtures of alkanethiols with alkanes.

Main Results:

• Achieved small mean absolute relative deviations in liquid densities and vapor pressures for 1-propanethiol, 1-butanethiol, and 1-pentanethiol.
• Demonstrated transferability of the force field to higher alkanethiols (1-hexanethiol, 1-octanethiol).
• Provided specific parameter sets for methanethiol and ethanethiol.
• Predicted shear viscosity with fair agreement to experimental data, despite it not being part of the parametrization.
• Observed excellent agreement between TAMie model predictions and experimental data for the phase behavior of binary alkanethiol-alkane mixtures.

Conclusions:

• The extended TAMie model provides accurate and transferable force field parameters for alkanethiols.
• The model successfully predicts thermophysical properties and phase behavior of pure alkanethiols and their mixtures.
• This work offers a valuable computational tool for the design and simulation of systems involving alkanethiols.