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arXiv · 2105.13736

Scaling properties of liquid dynamics predicted from a single configuration: Small rigid molecules

Zahraa Sheydaafar·Jeppe C. Dyre·Thomas B. Schrøder
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Abstract

Isomorphs are curves in the thermodynamic phase diagram along which structure and dynamics are invariant to a good approximation. There are two main ways to trace out isomorphs, the configurational-adiabat method and the direct-isomorph-check method. Recently a new method based on the scaling properties of forces was introduced and shown to work very well for atomic systems [T. B. Schroder, Phys. Rev. Lett. 129, 245501 (2022)]. A unique feature of this method is that it only requires a single equilibrium configuration for tracing out an isomorph. We here test generalizations of this method to molecular systems and compare to simulations of three simple molecular models: the asymmetric dumbbell model of two Lennard-Jones spheres, the symmetric inverse-power-law dumbbell model, and the Lewis-Wahnstr\"om o-terphenyl model. We introduce and test two force-based and one torque-based methods, all of which require just a single configuration for tracing out an isomorph. Overall, the method based on requiring invariant center-of-mass reduced forces works best.

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Zahraa Sheydaafar, Jeppe C. Dyre, Thomas B. Schrøder. 2021-05-28. Scaling properties of liquid dynamics predicted from a single configuration: Small rigid molecules. https://doi.org/10.1021/acs.jpcb.3c01574

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