On the water-carbon interaction for use in MD simulations of graphite and carbon nanotubes


T. Werder, J. H. Walther, R. L. Jaffe, T. Halicioglu, P. Koumoutsakos, Journal of Physical Chemistry B., 107, 1345-1352, 2003



A systematic molecular dynamics study shows that the contact angle of a water droplet on graphite changes significantly as a function of the water-carbon interaction energy. Together with the observation that a linear relationship can be established between the contact angle and the water monomer binding energy on graphite, a new route to calibrate interaction potential parameters is presented. Through a variation of the droplet size in the range from 1000 to 17 500 water molecules, we determine the line tension to be positive and on the order of 2×10(-10) J/m. To recover a macroscopic contact angle of 86degrees, a water monomer binding energy of -6.33 kJ mol(-1) is required, which is obtained by applying a carbon-oxygen Lennard-Jones potential with the parameters epsilon(CO)=0.392 kJ mol(-1) and sigma(CO)=3.19 Angstrom. For this new water-carbon interaction potential, we present density profiles and hydrogen bond distributions for a water droplet on graphite.