Pressure Effects on the Atomic and Electronic Structure of Aligned Small Diameter Carbon Nanotubes

Density functional methods have been used to calculate the electronic properties of aligned smalldiameter single-walled carbon nanotubes under hydrostatic pressures. Abrupt pressure induced semiconductor-metal and metal-semiconductor transitions concomitant with changes in structure are observed. Novel and unexpected unit cell nanotube cross-sections are found. These tubes are observed to form interlinking structures at very high pressures. The large changes in electronic structure and the ability of different small diameter nanotubes to respond in different pressure regimes suggest their use in high pressure multiple switching devices.