Water-carbon interactions 2: calibration of potentials using contact angle data for different interaction models


R. L. Jaffe, P. Gonnet, T. Werder, J. H. Walther, P. Koumoutsakos, Molecular Simulation, 30(4), 205-216, 2004



Molecular dynamics simulations of water droplets on graphite are carried out to determine the contact angle for different water-carbon potential functions. Following the procedure of Werder et al. [ J. Phys. Chem. B , 107 (2003) 1345], the C-O Lennard-Jones well depth is varied to recover the experimental value for the contact angle (84-86degrees) using a 2000-molecule water droplet and compensating for the line tension effect that lowers the contact angle for increasing droplet size. For the discrete graphite surface model studied by Werder et al. , the effects of adding C-H Lennard-Jones interactions and changing the long-range cut-off distance are considered. In addition, a continuum graphite surface model is studied for which the water-graphite interaction energy depends only on the normal distance ( z ) from the water oxygen to the surface. This new model, with z(-10) repulsion and z(-4) attraction, is formulated in terms of the standard Lennard-Jones parameters, for which the recommended values are sigma(CO) =3.19 Angstrom and epsilon(CO) =0.3651 kJ/mol.


DOI: 10.1080/08927020310001659124