Use of the McQuarrie equation for the computation of shear viscosity via equilibrium molecular dynamics
- Department of Chemical Engineering, Princeton University, Princeton, New Jersey 08544-5263 (US)
To date, the calculation of shear viscosity for soft-core fluids via equilibrium molecular dynamics has been done almost exclusively using the Green-Kubo formalism. The alternative mean-squared displacement approach has not been used, except for hard-sphere fluids, in which case the expression proposed by Helfand (Phys. Rev. 119, 1 (1960)) has invariably been selected. When written in the form given by McQuarrie ({ital Statistical} {ital Mechanics} (Harper Row, New York, 1976), Chap. 21), however, the mean-squared displacement approach offers significant computational advantages over both its Green-Kubo and Helfand counterparts. In order to achieve comparable statistical significance, the number of experiments needed when using the Green-Kubo or Helfand formalisms is more than an order of magnitude higher than for the McQuarrie expression. For pairwise-additive systems with zero linear momentum, the McQuarrie method yields frame-independent shear viscosities. The hitherto unexplored McQuarrie implementation of the mean-squared displacement approach to shear-viscosity calculation thus appears superior to alternative methods currently in use.
- DOE Contract Number:
- FG02-87ER13714
- OSTI ID:
- 5837245
- Journal Information:
- Physical Review, A; (USA), Vol. 43:8; ISSN 1050-2947
- Country of Publication:
- United States
- Language:
- English
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