Structural Metastability of Endohedral Silicon Fullerenes

TL;DR

This study systematically explores the structural stability of endohedral silicon fullerenes doped with various metals using density-functional theory, revealing that many proposed structures are metastable and more favorable configurations exist.

Contribution

It provides a comprehensive global optimization analysis showing that many existing structures are metastable and identifies more stable configurations for doped Si20 fullerenes.

Findings

Many proposed structures are metastable.

More stable configurations are found through global optimization.

Endohedral doping significantly affects stability.

Abstract

Endohedrally doped Si20 fullerenes appear as appealing building blocks for nanoscale materials. We investigate their structural stability with an unbiased and systematic global geometry optimization method within density-functional theory. For a wide range of metal doping atoms, it was sufficient to explore the Born Oppenheimer surface for only a moderate number of local minima to find structures that clearly differ from the initial endohedral cages, but are considerably more favorable in terms of energy. Previously proposed structures are thus all metastable.