Modeling the structural and transport behavior of hard ellipsoidal colloids using event-driven Brownian dynamics

  • Aleena Laganapan Department of Physics, University of Konstanz

Abstract

The theory for hard spheres is well established and has provided notable contributions in the field of colloid science. However, real systems are usually composed of anisotropic particles and there is significantly less theoretical information available for such systems. Hard ellipsoids can serve as natural extensions of the hard-sphere model. While the deviation from the hard-sphere geometry is small, it can already exhibit a wide range of new properties, such as liquid crystalline order, that one can explore. In this work, we study the dynamics of a system of colloidal hard ellipsoids in the context of glass transition using an event-driven Brownian dynamics model. The main challenge is to ensure that the detection of collisions and the sampling of random displacements do not produce overlaps. To this end, we develop an algorithm following the models proposed by Donev (2005) and De Michele (2007), where an overlap-potential that depends on the relative translation and rotation of a pair of ellipsoids, can be defined and used to predict the next collision time. To benchmark the model, transport properties such as the mean squared displacements and mean squared angular displacements are calculated and compared with experimental hard ellipsoidal colloids. By benchmarking the single particle motion, the structural and transport properties can be used to gain insight into dense dispersions of anisotropic colloids.

About the Speaker

Aleena Laganapan is a post-doctoral researcher and instructor at the Department of Physics of the University of Konstanz. She develops computational models for colloidal systems and investigates their applications in fundamental and applied physics. In particular, she works on developing coarse-grained simulation techniques, such as Brownian dynamics and multi-particle collision dynamics, that can describe the thermal fluctuations and hydrodynamic interactions at the mesoscopic level. She is currently working on the simulation of hard ellipsoids in dense suspensions, which can single out the essential aspects of anisotropic hard-core interactions. This work is studied in the context of developing fundamental theories for the glass transition of non-spherical systems.
She obtained her MS degree in Physics from the National Institute of Physics of the University of the Philippines Diliman in 2011. Her PhD dissertation work on the rheology and structure of ceramic suspensions was jointly supervised and she received her PhD in Ceramic Materials and Surface Treatments from the University of Limoges and PhD in Physics from the University of Genova in 2015.

Published
2018-04-27
How to Cite
[1]
A. Laganapan. Modeling the structural and transport behavior of hard ellipsoidal colloids using event-driven Brownian dynamics, Proceedings of the Samahang Pisika ng Pilipinas 36, SPP-2018-INV-2C-01 (2018). URL: https://paperview.spp-online.org/proceedings/article/view/SPP-2018-INV-2C-01.