  Solid-liquid friction plays a key role in nanofluidic systems. Yet, despite
decades of method development to quantify solid-liquid friction using molecular
dynamics (MD) simulations, an accurate and widely applicable method is still
missing. Here, we propose a method to quantify the solid-liquid friction
coefficient (FC) from equilibrium MD simulations of a liquid confined between
parallel solid walls. In this method, the FC is evaluated by fitting the
Green-Kubo (GK) integral of the S-L shear force autocorrelation for the range
of time scales where the GK integral slowly decays with time. The fitting
function was derived based on the analytical solution considering the
hydrodynamic equations in our previous work [H. Oga et al., Phys. Rev. Research
3, L032019 (2021)], assuming that the timescales related to the friction kernel
and to the bulk viscous dissipation can be separated. By comparing the results
with those of other equilibrium MD-based methods and those of non-equilibrium
MD for a Lennard-Jones liquid between flat crystalline walls with different
wettability, we show that the FC is extracted with excellent accuracy by the
present method, even in wettability regimes where other methods become
innacurate. We then show that the method is also applicable to grooved solid
walls, for which the GK integral displays a complex behavior at short times.
Overall, the present method extracts efficiently the FC for various systems,
with easy implementation and low computational cost.
