(723b) The Necessity of Large System Size in Interpreting Solvent Effects on Hydration and Kinetics in Atomistic Simulation
AIChE Annual Meeting
Friday, November 20, 2020 - 8:00am to 8:15am
The free energies to evacuate the first hydration shell around a solute and a cavity defined by the first hydration shell depend on the system size. This observation interpreted within the quasichemical theory shows that both the hydrophilic and the hydrophobic contributions to hydration depend on the system size, decreasing with increasing system size. The net hydration free energy benefits somewhat from the compensation of hydrophilic and hydrophobic contributions; nevertheless a large system appears necessary to describe correctly the balance of these contributions in the hydration of the solute. We illustrate this by discussing the hydration of a hard-sphere (a prototypical hydrophobe), imidazole (a small, polar solute), and a 56 residue protein GB (a polyampholyte).
We will also present results on the system size dependence of 1H NMR relaxation in water, illustrating one facet of system size dependence on system dynamics.