Dynamical properties of carbon nanotube welding into X junctions

We model the thermal, irradiation-induced fusion of single-wall carbon nanotubes into X junctions utilizing a Metropolis Monte Carlo algorithm enacting the most commonly observed transformations in sp2 carbon. We introduce the concept of the sp2 to sp3 parallel defect to model early stages of welding. Quantum mechanical tight-binding calculations are used in conjunction with the Landauer transport formalism to yield transport spectra and density of states at every step of the fusion process in metal/metal, semiconductor/metal, and semiconductor/semiconductor junctions. Insight into the coalescence transformation pathway is gained, and numerical simulations reveal the process as a series of five distinct phases based on the evolving Euler characteristic of the structure. We also highlight the use of the studied X junctions in device applications such as current/voltage dividers, voltage monitors, and logic gates.