Assessing parameters for ring polymer molecular dynamics simulations at low temperatures: DH + H chemical reaction

Ring polymer molecular dynamics (RPMD) is an accurate method for calculating thermal chemical reaction rates. It has recently been discovered that low-temperature calculations are strongly affected by the simulation parameters. Here, thermally activated DH + H -> D H2, we calculate RPMD rate constants at T = 50, 100, and 300 K demonstrate >= 100 standard input parameters yield results, but low temperatures (e.g., 50 K) one must increase asymptotic distance force constant, decrease umbrella integration step.