  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.
