(287b) ­Development of Accurate Potentials to Explore the Structure of Water on 2-D Materials

Authors: 
Deshmukh, S. A. - Presenter, Virginia Polytechnic Institute and State University
Singh, S., Virginia Polytechnic Institute and State University
Bejagam, K. K., Virginia Polytechnic Institute and State University
Water plays an important role in many biological and non-biological process. Structure of water at various interfaces and under confinement has always been the topic of immense interest. 2-D materials have shown great potential in surface coating applications and nanofluidic devices. However, the accurate atomic level understanding of the wettability of single layer of these 2-D materials is still lacking mainly due to lack of experimental techniques and computational methodologies including accurate force-field potentials and algorithms to calculate the contact angle of water. Here, we propose a new algorithm to calculate the accurate contact angle of liquid on a surface. By assuming the axisymmetric water droplet, all molecules were transformed from a 3-D space to a 2-D axisymmetric plane. Further, least-square fitting method was used to fit a circle through the 2-D axisymmetric plane. We employ this method of contact angle measurements to develop the accurate non-bonded potentials between water and graphene that reproduce the experimentally observed contact angle. Particle Swarm Optimization (PSO) algorithm has been employed to develop the non-bonded potentials between water and graphene. Different water models including SPC, SPC/E, SPC/Fw, and TIP3P were used to study the structure of water at the interface of graphene.