Soft-spring wall based non-periodic boundary conditions for non-equilibrium molecular dynamics of dense fluids

Ghatage, Dhairyashil and Tomar, Gaurav and Shukla, Ratnesh K (2015) Soft-spring wall based non-periodic boundary conditions for non-equilibrium molecular dynamics of dense fluids. In: JOURNAL OF CHEMICAL PHYSICS, 142 (12).

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Abstract

Non-equilibrium molecular dynamics (MD) simulations require imposition of non-periodic boundary conditions (NPBCs) that seamlessly account for the effect of the truncated bulk region on the simulated MD region. Standard implementation of specular boundary conditions in such simulations results in spurious density and force fluctuations near the domain boundary and is therefore inappropriate for coupled atomistic-continuum calculations. In this work, we present a novel NPBC model that relies on boundary atoms attached to a simple cubic lattice with soft springs to account for interactions from particles which would have been present in an untruncated full domain treatment. We show that the proposed model suppresses the unphysical fluctuations in the density to less than 1% of the mean while simultaneously eliminating spurious oscillations in both mean and boundary forces. The model allows for an effective coupling of atomistic and continuum solvers as demonstrated through multiscale simulation of boundary driven singular flow in a cavity. The geometric flexibility of the model enables straightforward extension to nonplanar complex domains without any adverse effects on dynamic properties such as the diffusion coefficient. (c) 2015 AIP Publishing LLC.

Item Type:	Journal Article
Publication:	JOURNAL OF CHEMICAL PHYSICS
Publisher:	AMER INST PHYSICS
Additional Information:	Copy right for this article belongs to th AMER INST PHYSICS, 1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USA
Keywords:	SHEAR VISCOSITY; SIMULATIONS; CONTINUUM; MODEL; FLOW; COMPUTER; PRESSURE; SYSTEMS
Department/Centre:	Division of Mechanical Sciences > Mechanical Engineering
Date Deposited:	13 May 2015 07:18
Last Modified:	13 May 2015 07:18
URI:	http://eprints.iisc.ac.in/id/eprint/51522

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