Mixing and Matching Simulations at Different Resolutions

In multiscale molecular dynamics simulations the accuracy of detailed models is combined with the efficiency of a reduced representation.For several applications _ namely those of sampling enhancement _ it is desirable to combine fine-grain (FG) and coarse-grained approaches into a single hybrid approach with an adjustable mixing parameter.We present a benchmark of three such schemes _ multigraining, temperature-scaling, and mass-scaling. These algorithms use different approaches for distributing forces across subsystems, and to preserve the integrity of FG molecules when the system is simulated close to the CG limit.The benchmark was applied to liquid hexadecane. The temperature-scaling scheme achieved a threefold sampling speedup with little deviation of FG properties. The multigraining scheme kept FG properties the best but provided little sampling speedup. The mass-scaling scheme also yielded a threefold speedup but deviated the most from FG properties.