Butane dihedral angle dynamics in water is dominated by internal friction.

ABSTRACT: The dihedral dynamics of butane in water is known to be rather insensitive to the water viscosity; possible explanations for this involve inertial effects or Kramers' turnover, the finite memory time of friction, and the presence of so-called internal friction. To disentangle these factors, we introduce a method to directly extract the friction memory function from unconstrained simulations in the presence of an arbitrary free-energy landscape. By analysis of the dihedral friction in butane for varying water viscosity, we demonstrate the existence of an internal friction contribution that does not scale linearly with water viscosity. At normal water viscosity, the internal friction turns out to be eight times larger than the solvent friction and thus completely dominates the effective fric

SUBMITTER: Daldrop JO 

PROVIDER: S-EPMC5960313 | biostudies-literature | 2018 May

REPOSITORIES: biostudies-literature