title: The R3-carbon allotrope: a pathway towards glassy carbon under high pressure.
abstract: Pressure-induced bond type switching and phase transformation in glassy carbon (GC) has been simulated by means of Density Functional Theory (DFT) calculations and the Stochastic Quenching method (SQ) in a wide range of pressures (0-79 GPa). Under pressure, the GC experiences a hardening transition from sp- and sp(2)-type to sp(3)-type bonding, in agreement with previous experimental results. Moreover, a new crystalline carbon allotrope possessing R3 symmetry (R3-carbon) is predicted using the stochastic SQ method. The results indicate that R3-carbon can be regarded as an allotrope similar to that of amorphous GC. A very small difference in the heat of formation and the coherence of the radial and angular distribution functions of GC and the R3-carbon structure imply that small perturbations to this crystalline carbon allotrope may provide another possible amorphization pathway of carbon besides that of quenching the liquid melt or gas by ultra-fast cooling.
authors.affiliation: Department of Materials and Engineering, Royal Institute of Technology, 10044 Stockholm, Sweden.
authors.forename: Xue
authors.initials: X
authors.lastname: Jiang
authors.forename: Cecilia
authors.initials: C
authors.lastname: Århammar
authors.forename: Peng
authors.initials: P
authors.lastname: Liu
authors.forename: Jijun
authors.initials: J
authors.lastname: Zhao
authors.forename: Rajeev
authors.initials: R
authors.lastname: Ahuja