On the thermal stability of pentagraphene

In the framework of the nonorthogonal tight-binding model, the thermal stability of pentagraphene is studied by numerical simulation using the molecular dynamics technique. Pentagraphene is the recently predicted two-dimensional allotropic modification of carbon, in which the C-C bonds form only pentagons, whereas the hexagons characteristic of carbon nanostructures are absent. It is found that the thermally activated rotation of one C-C bond by an angle of 45$^\circ$ initiates the formation of a defect region, which does not remain localized and rapidly propagates over the whole sample, leading eventually to the total destruction of the sample structure. Nevertheless, the probability of such rotation turns out to be so small that, even at room temperature, pentagraphene can preserve its structure for a fairly long time. This time decreases with the growth of the sample size.