Transitioning Model Potentials to Real Systems
Abstract
The parameters of two pairs of potentials that describe argon over its entire liquid phase at a fixed pressure were optimized through a novel application of constant temperature and pressure molecular dynamics (NPT-MD) and Monte Carlo (NPT-MC) computer simulations. The forms of these potentials were those of a modified Lennard-Jones potential and a Lennard-Jones potential (Lennard-Jones, J. E. Physica, Vol. 4. p. 941, 1937). The optimized potential determined using NPT-MD simulations reproduced experimental densities, internal energies, and enthalpies with an error less than 1% over most of the liquid range and yielded self-diffusion coefficients that were in excellent agreement with the experiment. The results using the potential determined by NPT-MC simulations were in almost as good agreement with deviations from experiments of no more than 5.89% for temperatures up to vaporization. Additionally, molar volumes predicted using this potential at pressures in the 100-600 atm range and over temperatures in the 100-140 K range were within 0.83% of experimental values. These results show that when properly parameterized, Lennard-Jones-like potentials could describe a system well over a large temperature range. Further, the method introduced was easy to implement and was independent of the form of the interaction potential used.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 2001
- Accession Number
- ADA387245
Entities
People
- Betsy M. Rice
- Scott D. Bembenek
Organizations
- United States Army Research Laboratory