Bayesian Estimation of the Hydroxyl Radical Diffusion Coefficient at Low Temperature and High Pressure from Atomistic Molecular Dynamics

TL;DR

This study employs a hierarchical Bayesian model to estimate the hydroxyl radical's diffusion coefficient in water under low temperature and high pressure conditions, relevant for understanding radiation effects in extreme environments.

Contribution

It introduces a novel Bayesian approach to accurately estimate radical diffusion coefficients from molecular dynamics data under extreme conditions.

Findings

Diffusion coefficient decreases with lower temperature and higher pressure.

Bayesian model provides credible intervals for diffusion estimates.

Results inform radiation damage models in extreme environments.

Abstract

The hydroxyl radical is the primary reactive oxygen species produced by the radiolysis of water, and is a significant source of radiation damage to living organisms. Mobility of the hydroxyl radical at low temperatures and/or high pressures is hence a potentially important factor in determining the challenges facing psychrophilic and/or barophilic organisms in high-radiation environments (e.g., ice-interface or undersea environments in which radiative heating is a potential heat and energy source). Here, we estimate the diffusion coefficient for the hydroxyl radical in aqueous solution, using a hierarchical Bayesian model based on atomistic molecular dynamics trajectories in TIP4P/2005 water over a range of temperatures and pressures.