Questioning the existence of a unique ground state structure for Si clusters

TL;DR

This paper challenges the idea of a single ground state structure for silicon clusters, showing that multiple configurations are energetically similar and affected by entropy, complicating experimental identification.

Contribution

It demonstrates through computational methods that silicon clusters lack a unique ground state, highlighting the importance of entropic effects and isotope configurations.

Findings

Multiple isomers are close in energy for Si clusters with >12 atoms.

Entropic effects can alter the energetic ordering of configurations.

Isotope effects influence the stability of symmetric configurations.

Abstract

Density functional and quantum Monte Carlo calculations challenge the existence of a unique ground state structure for certain Si clusters. For Si clusters with more than a dozen atoms the lowest ten isomers are close in energy and for some clusters entropic effects can change the energetic ordering of the configurations. Isotope pure configurations with rotational symmetry and symmetric configurations containing one additional isotope are disfavored by these effects. Comparisons with experiment are thus difficult since a mixture of configurations is to be expected at thermal equilibrium.