Nonequilibrium assembly of Lennard-Jones particles on a sphere

TL;DR

This paper models the nonequilibrium sequential assembly of Lennard-Jones particles on spherical shells, revealing diverse geometric structures and comparing them to equilibrium configurations, with implications for designing nanocontainers.

Contribution

It introduces a novel nonequilibrium assembly model for Lennard-Jones particles on spheres, generating diverse structures beyond known viral shells.

Findings

Generated shells exhibit square-triangular surface order.

Most structures resemble natural or synthetic protein complexes with specific symmetries.

Comparison shows differences between nonequilibrium and equilibrium assembled structures.

Abstract

Studying physical mechanisms and common geometric principles underlying known spherical packings is crucial for rational design of synthetic nanocontainers. Here we model the growth of small spherical shells containing n<72 identical particles that have their own curvature and interact with each other via the Lennard-Jones potential. The shell assembly is assumed to be nonequilibrium and sequential: at each step, a new particle is attached to the most energetically favorable position, after which the system relaxes. Along with well-known structures of the smallest icosahedral viral protein shells, the proposed mechanism generates a wide range of shells exhibiting square-triangular surface order. Most of such shells are the models of synthetic or natural protein complexes that have octahedral or tetrahedral symmetries and perform various functions. We compare the obtained structures with those resulting from the equilibrium assembly and corresponding to global energy minima. Also, we consider the temperature-dependent stochastic assembly and use the double-minimum Lennard-Jones-Gauss potential to mimic anisotropic particle interactions.