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Systematic search for low-enthalpy sp3 carbon allotropes using evolutionary metadynamics

Qiang Zhu, Qingfeng Zeng, and Artem R. Oganov
Phys. Rev. B 85, 201407(R) – Published 17 May 2012
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Abstract

We present a systematic search for low-energy metastable superhard carbon allotropes by using the recently developed evolutionary metadynamics technique. It is known that cold compression of graphite produces an allotrope at 15–20 GPa. Here we look for all low-enthalpy structures accessible from graphite. Starting from 2H- or 3R-graphite and applying a pressure of 20 GPa, a large variety of intermediate sp3 carbon allotropes were observed in evolutionary metadynamics simulation. Our calculation not only found all the previous proposed candidates for “superhard graphite,” but also predicted two allotropes (X-carbon and Y-carbon) showing unusual types of 5+7 and 4+8 topologies. These superhard carbon allotropes can be classified into five families based on 6 (diamond/lonsdaleite), 5+7 (M- and W-carbon), 5+7 (X-carbon), 4+8 (bct-C4), and 4+8 (Y-carbon) topologies. This study shows that evolutionary metadynamics is a powerful approach both to find the global minima and systematically search for low-energy metastable phases reachable from given starting materials.

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  • Received 3 March 2012

DOI:https://doi.org/10.1103/PhysRevB.85.201407

©2012 American Physical Society

Authors & Affiliations

Qiang Zhu1,*, Qingfeng Zeng1,2, and Artem R. Oganov1,3

  • 1Department of Geosciences, Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794, USA
  • 2National Key Laboratory of Thermostructure Composite Materials, Northwestern Polytechnical University, Xi'an 710072, People's Republic of China
  • 3Geology Department, Moscow State University, Moscow 119992, Russia

  • *qiang.zhu@stonybrook.edu

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Issue

Vol. 85, Iss. 20 — 15 May 2012

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