(145d) Extending the Capabilities of Molecular-Based Equations of State: Simultaneous Calculations of Phase Equilibria and Transport Properties

Allowing for simulation studies at spatial-temporal scales that are inaccessible to molecular methods, the dissipative particle dynamics method (DPD) [1,2] has become a robust tool for studying soft matter, including polymers, surfactants and colloids.  Since its development over 20 years ago, the fundamentals of the DPD method are now fairly well-established [3,4], as are many technical subtleties [e.g., 5], with frequently-emerging improvements [e.g., 6].  Extensions of the DPD method that impose energy conservation have also been developed, allowing for internal energy exchange between particles [7,8].  These factors led to many DPD simulation studies that provided insight into a variety of soft matter phenomena.  However, DPD is now being applied in other areas such as biophysics [9] and detonation physics [10,11].  Furthermore, it is expected that DPD will play an ever-increasing role in multiscale modeling approaches via bridging of the atomistic and continuum scales.

In this talk, we will present the status of one such emerging DPD application, namely, the study of the thermo-mechanical response of nanocomposites.  A number of simulation challenges exist for these materials, including the development of coarse-grain models and DPD methods that can capture the following known thermo-mechanical responses: (i) phase transitions; (ii) structural rearrangements and mechanical deformation (e.g., elastic-plastic deformation); and (iii) chemical reactions.  We will present the status of our ongoing project, including progress on coarse-grain model development [11], implementation of improved integrator algorithms for various DPD methods [12], the development of a constant-pressure, constant-enthalpy DPD method [12], and the development of a DPD framework that can mimic chemical reactivity (DPD-RX).

This effort is supported by the Institute for Multi-Scale Reactive Modeling of Insensitive Munitions (MSRM), which is a multi-team effort led by the U.S. Army Research Laboratory and the U.S. Army Armament Research, Development and Engineering Center, involving various other national laboratories and academic groups totaling over 20 scientists.  ML acknowledges funding through a Cooperative Agreement with the U.S. Army Research Laboratory.

References:

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[11] Moore, J.D., S. Izvekov, M. Lísal and J.K. Brennan, Proceedings of the 17^th Shock Compression of Condensed Matter, Chicago, IL (2011).

[12] Lísal, M., J.K. Brennan and J. Bonet Avalos, J. Chem. Phys., 135, 204105 (2011).