Piezoelectric molecular dynamics model for boron nitride nanotubes

A classical molecular dynamics model with an incorporated strain-dependent dipole potential energy term is introduced to represent the piezoelectric properties of boron nitride nanotubes (BNNTs). The model allows for an analytical expression of the piezoelectric tensor of hexagonal BN monolayers in terms of the properties of the interatomic potential and two fitting parameters. The deformation-induced polarization predicted by this model is verified against the results of previously published electronic structure (ab-initio and tight-binding) calculations. The model works well for BNNTs over the full range of chiral angles from φ = 0° (zig-zag tubes) to φ = 30° (armchair tubes) and under loading in both tensile and twist modes. The presented model can be a foundation for atomic-level modeling of the electroactive properties of large systems of BNNTs and BNNT composites, as well as a base for analytical studies.