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Capillary Waves at Liquid/Vapor Interfaces: A Molecular Dynamics Simulation

Journal Article · · Physical Review E

Evidence for capillary waves at a liquid/vapor interface are presented from extensive molecular dynamics simulations of a system containing up to 1.24 million Lennard-Jones particles. Careful measurements show that the total interfacial width depends logarithmically on L{sub {parallel}}, the length of the simulation cell parallel to the interface, as predicted theoretically. The strength of the divergence of the interfacial width on L{sub {parallel}} depends inversely on the surface tension {gamma}. This allows us to measure {gamma} two ways since {gamma} can also be obtained from the difference in the pressure parallel and perpendicular to the interface. These two independent measures of {gamma} agree provided that the interfacial order parameter profile is fit to an error function and not a hyperbolic tangent, as often assumed. We explore why these two common fitting functions give different results for {gamma}.

Research Organization:
Sandia National Labs., Albuquerque, NM (US); Sandia National Labs., Livermore, CA (US)
Sponsoring Organization:
US Department of Energy (US)
DOE Contract Number:
AC04-94AL85000
OSTI ID:
9474
Report Number(s):
SAND99-1912J
Journal Information:
Physical Review E, Journal Name: Physical Review E
Country of Publication:
United States
Language:
English