Thermal stability and decomposition mechanisms of hexatetracarbon: Tight-binding molecular dynamics and density functional theory study

Abstract

In this work, we carry out molecular dynamics and ab initio modeling to determine the thermal decomposition channels and thermal stability of the recently proposed 2D carbon allotrope, hexatetracarbon (HTC). To take into account the role of edges in the initialization of decay, we considered finite size cluster models of HTC passivated by hydrogen. Four models were selected for the study: [Formula: see text], [Formula: see text] [Formula: see text] and [Formula: see text]. Molecular dynamics and hyperdynamics was carried out using the NTBM non-orthogonal tight-binding model. For ab initio calculations, we used the electron density functional theory with the B3LYP three-parameter hybrid functional and the 6-311G[Formula: see text] electronic basis set. Prismane [Formula: see text] demonstrated the highest stability due to the high energy barrier of 1.5 eV preserving its decomposition. Larger clusters possessed lower barriers in the 0.65–0.9 eV range. We concluded that the HTC edges are unstable at room temperatures. However, the destruction of some interlayer bonds can result in strain relaxation and increase of stability. We believe that HTC could exist at room temperatures in the form of nanosized quantum dots that appeared from bilayer graphene under high pressure.