Abstract
The present study simulates some material properties and phenomena of water in the minute nano scale by molecular dynamics simulation theory and high performance programming with MPI parallel method. We also further discuss those simulation results and offer some arguments with appropriate point of physical view. In a homogenous system, water molecules are simulated at two different thermodynamic states including liquid at various different temperature and supercritical water. According to radial distribution functions, a distance of hydrogen bond between two water molecules is about 1.86 angstrom. Self-diffusion coefficient increases with the temperature and decreases with pressure. Capability to diffuse at supercritical states is better than at liquid states. Moreover in a liquid water state, there are much higher percentage with three or four the average number of hydrogen bonds formed by each molecule and stronger hydrogen interaction than that in a supercritical state. Summing percentage of two parts is about between 59% and 86%. Simulating evaporation processes of a thin liquid water film demonstrates that there is a transition layer with density varying continuously on a thin liquid film and this interfacial thickness increases with increasing temperature. Based on the Schrage model, the evaporation coefficients of thin liquid film are between 0.3 from 0.6 and increase with interfacial pressure. It is very evident to observe that molecules take place processes of evaporation and condensation at the interface of liquid film and collisions in a vacuum by using image software celled PV-WIN. There are various different physical processes when a nano-water droplet is close to an isothermal platinum surface: contact, adsorption, surface diffusion, evaporation and platinum surface to dry off, nucleation of cluster and reformation of droplet. Besides, total energy of droplets changes during different states. Finally, according to measuring contact angle, the platinum surface is found to be hydrophilic to the nano-water droplet.