# Hydrogen bond analysis of confined water in mesoporous silica using the reactive force field

## TL;DR

This study uses molecular dynamics simulations with a reactive force field to analyze the structural and dynamical properties of water confined in mesoporous silica, focusing on hydrogen bonding behavior.

## Contribution

It provides detailed insights into hydrogen bond dynamics and structural properties of confined water, validated against experimental data, using large-scale reactive force field simulations.

## Key findings

- Hydrogen bonds involving silanol groups have longer lifetimes.
- The diffusion coefficient of confined water is reduced compared to bulk water.
- Hydrogen bond strength varies with radial position in the pore.

## Abstract

The structural and dynamical properties of water confined in nanoporous silica with a pore diameter of 2.7 nm were investigated by performing large-scale molecular dynamics simulations using the reactive force field. The radial distribution function and diffusion coefficient of water were calculated, and the values at the center of the pore agreed well with experimental values for real water. In addition, the pore was divided into thin coaxial layers, and the average number of hydrogen bonds, hydrogen bond lifetime, and hydrogen bond strength were calculated as a function of the radial distance from the pore central axis. The analysis showed that hydrogen bonds involving silanol (Si-OH) have a longer lifetime, although the average number of hydrogen bonds per atom does not change from that at the pore center. The longer lifetime, as well as smaller diffusion coefficient, of these hydrogen bonds is attributed to their greater strength.