We report a new carbon allotrope belonging to a class of topological nodal line semimetals, based on global optimization and first-principles density functional calculations. The new carbon phase in monoclinic C2/m space group, termed m-C8, consists of five-membered rings with sp3 hybridized bonds and sp2-bonded carbon networks. The band structure exhibits linear dispersions around the Fermi level where the valence and conduction bands touch each other. Based on the analysis of X-ray diffraction spectra and enthalpy-pressure curves, we propose that m-C8 can be present in detonation soot and a phase transition from graphite to m-C8 can occur under pressure.
- Ha-Jun Sung
- Sunghyun Kim
- Kee Joo Chang
