Structure and Dynamics of Water Confined in a Boron Nitride Nanotube

Abstract

Recent molecular dynamics simulations have shown that a finite-length (5,5) boron nitride nanotube (BNNT) in contact with an aqueous reservoir has superior water permeation properties compared to a (5,5) carbon nanotube of similar diameter and length. In this work, by using density functional theory (DFT), we compute the electrostatic potential arising from the weak ionic and covalent bonding of B−N. Quantum partial charges of B and N atoms, determined by matching the electrostatic potential computed by the DFT, are then included in molecular dynamics simulations to investigate the structure and dynamics of water confined in BNNTs of sizes ranging from (5,5) to (10,10). When partial charges are included, we observe that the wetting behavior of the (5,5) BNNT has improved and the single-file water chain in both (5,5) and (6,6) BNNTs has an L-defect. Further, with partial charges, except for a (9,9) BNNT which exhibits anomalous behavior, the diffusion coefficient of confined water molecules in (5,5), (6,6)...