New Force-Field for Organosilicon Molecules in the Liquid Phase.

Miguel Jorge,Maria Cecilia Barrera,Andrew W Milne,José R B Gomes

doi:10.1021/acsphyschemau.1c00014

Miguel Jorge, Maria Cecilia Barrera + Show 2 more

Open Access

https://doi.org/10.1021/acsphyschemau.1c00014

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Abstract

In this paper, we present a new molecular model that can accurately predict thermodynamic liquid state and phase-change properties for organosilicon molecules including several functional groups (alkylsilane, alkoxysilane, siloxane, and silanol). These molecules are of great importance in geological processes, biological systems, and material science, yet no force field currently exists that is widely applicable to organosilicates. The model is parametrized according to the recent Polarization-Consistent Approach (PolCA), which allows for polarization effects to be incorporated into a nonpolarizable model through post facto correction terms and is therefore consistent with previous parametrizations of the PolCA force field. Alkyl groups are described by the United-Atom approach, bond and angle parameters were taken from previous literature studies, dihedral parameters were fitted to new quantum chemical energy profiles, point charges were calculated from quantum chemical optimizations in a continuum solvent, and Lennard-Jones dispersion/repulsion parameters were fitted to match the density and enthalpy of vaporization of a small number of selected compounds. Extensive validation efforts were carried out, after careful collection and curation of experimental data for organosilicates. Overall, the model performed quite well for the density, enthalpy of vaporization, dielectric constant, and self-diffusion coefficient, but it slightly overestimated the magnitude of self-solvation free energies. The modular and transferable nature of the PolCA force field allows for further extensions to other types of silicon-containing compounds.

Highlights

Silicon is the second most abundant element in the Earth’s crust, behind oxygen, accounting for 28.8% by mass.[1]
Because parametrizing a force field for all possible organosilicate molecules is a formidable task, in the present paper, which is meant as the first step toward this ultimate goal, we focus on a subset of this class of molecules
We reported the parametrization of a new model for organosilicate molecules in the liquid phase

Summary

Introduction

Silicon is the second most abundant element in the Earth’s crust, behind oxygen, accounting for 28.8% by mass.[1]. Some of that silicon is harvested by organisms like diatoms and sponges to yield intricately beautiful hierarchical structures in a process called biosilicification.[2,3] Silicon is at the heart of the computer revolution, as the core material in the manufacture of semiconductor chips.[4] Organosilicon molecules (e.g., dichlorodimethylsilane) are used as precursors in the synthesis of silicone rubbers and polymers, including the widely used polydimethylsiloxane.[5] As a final example, of more direct relevance to our research, organosilicon compounds like tetraethoxysilane are key precursor species in the synthesis of porous materials like zeolites,[6,7] periodic mesoporous silicas,[8,9] organosilicas,[10,11] and bioinspired silica.[3,12]

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