A model study of the conversion of energy from a chemical reaction into motion through a solvation motor

Molecular dynamics simulations with the explicit simple solvent model are examined to study the conversion of energy from chemical reactions into the motion of a motor molecule due to the solvation change around the reaction site on the motor molecule. Here, the appearance and disappearance of the attractive interaction between a reaction site and solvent molecules are introduced as a "chemical" reaction. Each of the events for the motion of a solvation motor resembles a random walk. However, on average, changes in the solvation structure due to the "chemical" reaction cause the forward motion, and the displacement of the motor becomes larger than the motor size. The motor is accelerated twice. The collision of solvent molecules with the reaction site caused by the appearance of attraction is dominant as the first driving force during the "chemical" reaction period. The second acceleration is driven by the scattering of solvent molecules near the "chemical" reaction site on the motor after the "chemical" reaction period. Although the driving force becomes larger as the packing fraction of the solvent increases, the displacement becomes smaller due to the friction.