title: Predicting experimentally stable allotropes: Instability of penta-graphene.
abstract: In recent years, a plethora of theoretical carbon allotropes have been proposed, none of which has been experimentally isolated. We discuss here criteria that should be met for a new phase to be potentially experimentally viable. We take as examples Haeckelites, 2D networks of sp(2)-carbon-containing pentagons and heptagons, and "penta-graphene," consisting of a layer of pentagons constructed from a mixture of sp(2)- and sp(3)-coordinated carbon atoms. In 2D projection appearing as the "Cairo pattern," penta-graphene is elegant and aesthetically pleasing. However, we dispute the author's claims of its potential stability and experimental relevance.
authors.affiliation: Institut des Matériaux Jean Rouxel, CNRS UMR 6502, Université de Nantes, 44322 Nantes, France; chris.ewels@cnrs-imn.fr kroto@chem.fsu.edu.
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Ewels
authors.affiliation: Institut des Sciences Chimiques de Rennes, UMR 6226 CNRS, Université de Rennes 1, 35042 Rennes, France;
authors.forename: Xavier
authors.initials: X
authors.lastname: Rocquefelte
authors.affiliation: Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306; chris.ewels@cnrs-imn.fr kroto@chem.fsu.edu.
authors.forename: Harold W
authors.initials: HW
authors.lastname: Kroto
authors.affiliation: Department of Chemistry, University of Surrey, Guildford, Surrey GU2 7XH, United Kingdom; School of Electrical and Electronic Engineering, University of Newcastle, Newcastle upon Tyne NE1 7RU, United Kingdom.
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Rayson
authors.affiliation: School of Electrical and Electronic Engineering, University of Newcastle, Newcastle upon Tyne NE1 7RU, United Kingdom.
authors.forename: Patrick R
authors.initials: PR
authors.lastname: Briddon
authors.affiliation: Department of Chemistry, University of Surrey, Guildford, Surrey GU2 7XH, United Kingdom;
authors.forename: Malcolm I
authors.initials: MI
authors.lastname: Heggie
keywords: Haeckelite; allotropes; modeling; nanocarbon; penta-graphene