A Playground for Heavy Atom Tunnelling: Neutral Substitutional Defect Rearrangement from Diamondoids to Diamonds

Many diamond properties are defined by substitutional defects (i. e., a carbon atom replaced by another element), which may involve the formation of structural isomers that can interconvert. Herein, we analysed by computational means the structure, thermodynamics, and kinetics of substitutional nitrogen, boron, and oxygen from small diamondoids up to the diamond bulk, focusing on the possibility of heavy atom quantum tunnelling rearrangement between the isomers. The large range of threshold energies and bond lengths lead to a variety of intriguing behaviours, including cage size dependent thermally activated tunnelling of nitrogen, and quantum delocalization of boron. In addition, we predict that applying an external electric field makes it possible to control the rearrangement thermodynamics and kinetics through tunnelling, which lets us hypothesize that these systems can potentially be used as atomic memory devices.