FFSiOH: a New Force Field for Silica Polymorphs and Their Hydroxylated Surfaces Based on Periodic B3LYP Calculations

Abstract

A partial charge shell-ion model potential for silica polymorphs and their hydroxylated surfaces(FFSiOH) was parametrized in a self-consistent way using periodic B3LYP results for bulk R-cristobaliteand the (100) and (001) hydroxylated surfaces. The reliability of the new potentials was checked bycomparing structures, vibrational frequencies and relative phase stabilities of dense bulk silica polymorphs,namely R-quartz, R-cristobalite, R-tridymite, and Stishovite with both experimental and B3LYP data.The FFSiOH was also checked for computing structural and vibrational features of representative all-silica microporous materials, namely edingtonite, chabazite, and faujasite. As a last step, FFSiOH wasadopted to predict OH stretching vibrational frequencies and relative thermodynamic stability of themost common fully hydroxylated surfaces of the dense silica polymorphs, the (100) and (001) facesof all-silica edingtonite, the features of the local Si-defect in chabazite and sodalite known as (SiOH)4hydrogarnet and the geometries of H-bonded silanol groups of an amorphous silica surface. In all casesexcellent agreement resulted between FFSiOH and B3LYP periodic data and experimental data, whenavailable. The new FFSiOH force field opens up the molecular simulation of materials in which thesurface hydroxyl groups play a key role, as is the case for amorphous silica surfaces, all-silica zeoliteexternal surfaces, and the internal walls of mesoporous materials

Prediction of Specific Biomolecule Adsorption on Silica Surfaces as a Function of pH and Particle Size

“…Prior force fields often required fixed atoms to avoid collapse of the models in the simulation, neglected the pH dependence of the surface chemistry, and involved other drastic approximations so that even approximate predictions of specific binding of biomolecules were essentially impossible. [43][44][45][46][47][48][49][50][51][52][53][54][55][56] The new, thermodynamically consistent silica parameters are compatible with comprehensive harmonic force fields for biopolymers, organic molecules, and inorganic compounds such as 7 CHARMM, AMBER, PCFF, COMPASS, CVFF, and INTERFACE. 26,37 The compatibility enables insight into a limitless number of silica hybrid materials by the possible combination of thousands of distinct silica surface structures with billions of distinct biopolymers, surfactants, and receptor molecules across a wide range of concentrations and solution conditions.…”

A reactive molecular dynamics simulation of the silica-water interface

“…9 Molecular dynamics ͑MD͒ techniques, due to their ability to probe nanoscale spatiotemporal processes, can provide valuable insights into this problem. Conventional classical MD has the ability to simulate bulk properties of a-SiO 2 .…”

A first principles based polarizable O(N) interatomic force field for bulk silica

“…We shall therefore restrict ourselves to modeling the dominant low temperature and low-pressure forms of bulk silica, ␣-quartz and amorphous silica, which are the most relevant to fracture calculations. While various attempts have been made to represent surface chemistry processes, 32,33 this is not our intention in this work. Where bond-breaking processes are important, we propose to use this potential within a QM/MM embedding scheme, relying on ab initio techniques to describe a small region with high accuracy, with the force field providing the correct elastic environment.…”