title: Low-temperature phase transformation from graphite to sp3 orthorhombic carbon.
abstract: We identify by ab initio calculations an orthorhombic carbon polymorph in Pnma symmetry that has the lowest enthalpy among proposed cold-compressed graphite phases. This new phase contains alternating zigzag and armchair buckled carbon sheets transformed via a one-layer by three-layer slip mechanism. It has a wide indirect band gap and a large bulk modulus that are comparable to those of diamond. Its simulated x-ray diffraction pattern best matches the experimental data. Pressure plays a key role in lowering the kinetic barrier during the phase conversion process. These results provide a comprehensive understanding and an excellent account for experimental findings.
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, China.
authors.forename: Jian-Tao
authors.initials: JT
authors.lastname: Wang
authors.forename: Changfeng
authors.initials: C
authors.lastname: Chen
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Kawazoe