Novel sp3 forms of carbon predicted by evolutionary metadynamics and analysis of their synthesizability using transition path sampling

S. E. Boulfelfel, Q. Zhu, A. R. Oganov

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)

Abstract

Experiments on cold compression of graphite have indicated the existence of a new superhard and transparent allotrope of carbon. Numerous metastable candidate structures featuring different topologies have been proposed for "superhard graphite", showing a good agreement with experimental X-ray data. In order to determine the nature of this new allotrope, we use evolutionary metadynamics to systematically search for low-enthalpy sp 3 carbon structures easily accessible from graphite and we employ molecular-dynamics transition path sampling to investigate the corresponding kinetic pathways starting from graphite at 15-20 GPa. Real transformation kinetics are computed and physically meaningful transition mechanisms are produced at the atomistic level of detail in order to demonstrate how nucleation mechanism and transformation kinetics lead to M-carbon as final product of cold compression of graphite. This establishes M-carbon as an experimentally synthesized carbon allotrope.

Original languageEnglish
Pages (from-to)350-359
Number of pages10
JournalJournal of Superhard Materials
Volume34
Issue number6
DOIs
Publication statusPublished - Nov 2012
Externally publishedYes

Keywords

  • carbon
  • high pressure
  • metadynamics
  • molecular dynamics
  • polymorphism
  • superhard material

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