Variational limits on the Helmholtz free energy of simple fluids

Journal Article · Fri Dec 01 04:00:00 EST 1989 · Physical Review (Section) A: General Physics; (USA)

DOI:https://doi.org/10.1103/PhysRevA.40.6379· OSTI ID:7163608

Boercker, D B; Young, D A ^[1]

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1. Lawrence Livermore National Laboratory, University of California, Livermore, California 94550 (US)

Accurate radial-distribution functions obtained from a thermodynamically consistent integral equation are used to calculate upper and lower bounds to the Helmholtz free energies of several inverse-power potential fluids and the Lennard-Jones fluid. Comparisons with results from Monte Carlo simulations indicate that the true free energies are tightly bracketed by the variational bounds. In addition, the simulations agree with the arithmetic mean of the limits near melt to within about 0.03{ital Nk}{sub {ital B}}T for inverse power fluids and about 0.06{ital Nk}{sub {ital B}}T for Lennard-Jones fluids. These results indicate that it is possible to obtain accurate free energies very efficiently by the variational method.

• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 7163608
• Journal Information: Physical Review (Section) A: General Physics; (USA), Journal Name: Physical Review (Section) A: General Physics; (USA) Vol. 40:11; ISSN PLRAA; ISSN 0556-2791
• Country of Publication: United States
• Language: English

Related Subjects

640410* -- Fluid Physics-- General Fluid Dynamics
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
COMPARATIVE EVALUATIONS
ENERGY
EVALUATION
FLUIDS
FREE ENERGY
LENNARD-JONES POTENTIAL
LIMITING VALUES
MONTE CARLO METHOD
PHYSICAL PROPERTIES
POTENTIALS
THERMODYNAMIC PROPERTIES
VARIATIONAL METHODS