Investigation of the quasi-universality of bridge functions in classical liquids
Title: Investigation of the quasi-universality of bridge functions in classical liquids
SNIC Project: SNIC 2019/7-45
Project Type: SNIC Small Compute
Principal Investigator: Panagiotis Tolias <>
Affiliation: Kungliga Tekniska högskolan
Duration: 2019-06-20 – 2020-07-01
Classification: 10304


It has been recently proposed that reduced-unit bridge functions are isomorph invariant for a broad class of model liquids coined as R-simple, which implies that bridge functions depend exclusively on the reduced excess entropy. This conjecture has been employed in order to formulate an integral equation theory approach for strongly coupled Yukawa and bi-Yukawa one component plasmas. In spite of not invoking adjustable parameters, the approach has managed to reproduce the thermodynamic and structural properties of such model systems with an unprecedented accuracy. This suggests that the underlying invariance ansatz must hold true at least in an approximate manner which has important implications for the well-documented quasi-universal behavior of classical liquids. The next step is to extract bridge functions from molecular dynamics (MD) simulations at various thermodynamic states of classical dense liquids that exhibit isomorph invariance (pair-interaction potentials of the Lennard-Jones, Yukawa and EXP type) in order to directly test the conjecture. This project constitutes the first step towards this goal. The aim is to optimize the basic numerical parameters, extraction techniques and postprocessing algorithms in MD simulations with a relatively small number of particles before proceeding to large scale simulations.