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  • Katherine Hollingsworth

Materials Design, Inc.'s Philippe Ungerer at the Mod Mol Workshop

Philippe Ungerer will be attending the Mod Mol Workshop organized by DECHEMA, Frankfurt, March 9-10 , 2017. Philippe's talk is entitled 'Prediction of Properties in Metastable Conditions.' It would be our pleasure to see you in Frankfurt!

Here is the abstract:

Prediction of Properties in Metastable Conditions

Marianna Yiannourakou, Materials Design sarl, Montrouge, France; Philippe Ungerer, Materials Design sarl, Montrouge, France ; Jean-Marie Teuler, LCP-Université Paris Saclay-CNRS, Orsay, France ; Véronique Lachet, IFPEN, Rueil-Malmaison, France


It is well accepted that liquids may be metastable on significant time scales when the nucleation process is slow or when it is hindered by confinement (Debenedetti, Metastable liquids – Concepts and principles, 1997). Liquid metastability may lead to significant damage in some instances, such as cavitation-induced corrosion or explosive boiling of superheated liquids. Simulation can help in better understanding these phenomena, particularly in cases where experimenting is challenging.

In the present work, we discuss how classical tools of molecular simulation (MD, MC) can be used to investigate the properties of bulk molecular liquids, either nonpolar (methane) or hydrogen-bonded (water, isopropanol) in metastable conditions. We consider particularly the conditions where the liquid phase is in thermal equilibrium (Boltzmann distribution of energies), mechanically stable (positive compressibility coefficient) and thermodynamically unstable (no vapor phase).

In a first step we use the classical Monte Carlo techniques to investigate the pressure-volume relationship of metastable liquids in the NVT or NPT ensembles and classical forcefields. It is found that these techniques yield consistent phase properties, particularly negative pressures down to several hundreds of bars. Validation with experimental trends (liquid density, isothermal compressibility) is very encouraging.

In a second step, we discuss how other properties of metastable liquids could be derived and compared with stable liquids. Pressure-volume relationship for mixtures, heat capacity, speed of sound is considered from Monte Carlo simulations, and transport properties (diffusivity, viscosity, thermal conductivity) are considered from molecular dynamics.

It is concluded that molecular simulation can be applied reliably to the understanding of metastable liquid phases. Perspectives of applications in other types of metastability are outlined.

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