Face-Centered-Cubic B$_{80}$ Metal: Density functional theory calculations

TL;DR

This study uses density functional theory to predict that B80 fullerenes can form stable face-centered-cubic metallic solids with specific structural distortions and bonding characteristics.

Contribution

It is the first to demonstrate the formation of stable B80 fullerene-based fcc solids and analyze their electronic and structural properties.

Findings

B80 fullerenes can condense into stable fcc solids

The fcc B80 solid is metallic

Structural distortion lowers symmetry from Ih to Th

Abstract

By means of ab initio calculations within the density functional theory, we have found that B80 fullerenes can condense to form stable face-centered-cubic fcc solids. It is shown that when forming a crystal, B80 cages are geometrically distorted, the Ih symmetry is lowered to Th, and four boron-boron chemical bonds are formed between every two nearest neighbor B80 cages. The cohesive energy of B80 fcc solid is 0.23 eV/atom with respect to the isolated B80 fullerene. The calculated electronic structure reveals that the fcc B80 solid is a metal. The predicted solid phase would constitute a form of pure boron and might have diverse implications. In addition, a simple electron counting rule is proposed, which could explain the stability of B80 fullerene and the recently predicted stable boron sheet.