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Volume 133, Issue 16, 28 October 2010
We present a new method for introducing stable nonequilibrium velocity and temperature gradients in molecular dynamics simulations of heterogeneous systems. This method extends earlier reverse nonequilibrium molecular dynamics (RNEMD) methods which use momentum exchange swapping moves. The standard swapping moves can create nonthermal velocity distributions and are difficult to use for interfacial calculations. By using nonisotropic velocity scaling (NIVS) on the molecules in specific regions of a system, it is possible to impose momentum or thermal flux between regions of a simulation while conserving the linear momentum and total energy of the system. To test the method, we have computed the thermal conductivity of model liquid and solid systems as well as the interfacial thermal conductivity of a metal-water interface. We find that the NIVS-RNEMD improves the problematic velocity distributions that develop in other RNEMD methods.
Communication: Relationships between Intermolecular potential, thermodynamics, and dynamic scaling in viscous systems133(2010); http://dx.doi.org/10.1063/1.3496999View Description Hide Description
In this communication, we provide a recipe for a consistent relation between dynamic scaling and thermodynamic properties well-grounded by the same intermolecular generalized Lennard-Jones potential, which is derived by using an essentially modified Avramov model within the framework of the “thermodynamic scaling” idea. This relation is experimentally verified very well for supercooled van der Waals liquids, and consequently, it can be a good basis for a proper universal description of molecular dynamics and thermodynamics of viscoussystems.