New crystal structure prediction of fully hydrogenated borophene by first principles calculations

TL;DR

This study predicts new stable crystal structures of fully hydrogenated borophene (borophane) using first principles calculations, revealing a particularly stable washboard-like conformer with promising electronic and mechanical properties.

Contribution

The paper introduces four new borophane conformers with lower energy than previously reported structures, expanding the understanding of borophene's structural diversity.

Findings

W-borophane is 113.41 meV/atom more stable than C-borophane.

All four conformers are dynamically stable based on phonon dispersion analysis.

W-borophane exhibits a Dirac cone electronic structure and excellent mechanical properties.

Abstract

New crystal structures of fully hydrogenated borophene (borophane) have been predicted by first principles calculation. Comparing with the chair-like borophane (C-boropane) that has been reported in literature, we obtained four new borophane conformers with much lower total-energy. The most stable one, washboard-like borophane (W-borophane), has energy about 113.41 meV/atom lower than C-borophane. In order to explain the relative stability of different borophane conformers, the atom configuration, density of states, charge transfer, charge density distribution and defect formation energy of B-H dimer have been calculated. The results show that the charge transfer from B atoms to H atoms is crucial for the stability of borophane. In different borophane conformers, the bonding characteristics between B and H atoms are similar, but the B-B bonds in W-borophane are much stronger than that in C-borophane or other structures. In addition, we examined the dynamical stability of borophane conformers by phonon dispersions and found that the four new conformers are all dynamically stable. Finally the mechanical properties of borophane conformers along an arbitrary direction have been discussed. W-borophane possesses unique electronic structure (Dirac cone), good stability and superior mechanical properties. W-borophane has broad perspective for nano electronic device.