Al₂C monolayer: the planar tetracoordinate carbon global minimum.

Inspired by our theoretical finding that C₂Al₆(2-) has a planar D₂h minimum with two planar tetracoordinate carbons (ptCs), we computationally designed a new two-dimensional (2D) inorganic material, an Al₂C monolayer. All carbons in this monolayer are ptC's, stabilized inductively by binding to four electropositive Al atoms in the same plane. The Al₂C monolayer is semiconducting with an indirect minimum band gap and a slightly larger direct band gap. Good persistence of the Al₂C monolayer is indicated by its moderate cohesive energy, the absence of imaginary modes in its phonon spectrum, and the high melting point predicted by molecular dynamics (MD) simulations. Moreover, a particle-swarm optimization (PSO) global minimum search found the Al₂C monolayer to be the lowest-energy 2D structure compared to other Al₂C alternatives. Dividing the Al₂C monolayer results in one-dimensional (1D) Al₂C nanoribbons, which are computed to have quite rich characteristics such as direct or indirect band gaps with various values, depending on the direction of the division and the resulting edge configuration.

[1]  J. B. Collins,et al.  Molecular orbital study of tetrahedral, planar, and pyramidal structures of the isoelectronic series BH4-, CH4, NH4+, AlH4-, SiH4, and PH4+ , 1980 .

[2]  Patrick Vogt,et al.  Silicene: compelling experimental evidence for graphenelike two-dimensional silicon. , 2012, Physical review letters.

[3]  M. Klein,et al.  Nosé-Hoover chains : the canonical ensemble via continuous dynamics , 1992 .

[4]  X. Zeng,et al.  Planar tetracoordinate carbon strips in edge decorated graphene nanoribbon. , 2010, Journal of the American Chemical Society.

[5]  P. Schleyer,et al.  A new, general strategy for achieving planar tetracoordinate geometries for carbon and other second row periodic elements , 1991 .

[6]  Shih‐Yuan Liu,et al.  A single-component liquid-phase hydrogen storage material. , 2011, Journal of the American Chemical Society.

[7]  C. Corminboeuf,et al.  Theoretical analysis of the smallest carbon cluster containing a planar tetracoordinate carbon. , 2004, Journal of the American Chemical Society.

[8]  R. Keese,et al.  Carbon flatland: planar tetracoordinate carbon and fenestranes. , 2006, Chemical reviews.

[9]  Zhi‐Xiang Wang,et al.  Construction Principles of "Hyparenes": Families of Molecules with Planar Pentacoordinate Carbons , 2001, Science.

[10]  P. Schleyer,et al.  Myriad planar hexacoordinate carbon molecules inviting synthesis. , 2007, Journal of the American Chemical Society.

[11]  Chengchun Tang,et al.  Prediction of Two-Dimensional Boron Sheets by Particle Swarm Optimization Algorithm , 2012 .

[12]  G. Kresse,et al.  Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set , 1996 .

[13]  Yan-Bo Wu,et al.  Computationally designed families of flat, tubular, and cage molecules assembled with "starbenzene" building blocks through hydrogen-bridge bonds. , 2010, Chemistry.

[14]  Hai‐feng Zhang,et al.  Pentaatomic Tetracoordinate Planar Carbon, [CAl4]2−: A New Structural Unit and Its Salt Complexes , 2000 .

[15]  G. Scuseria,et al.  Hybrid functionals based on a screened Coulomb potential , 2003 .

[16]  Andre K. Geim,et al.  Electric Field Effect in Atomically Thin Carbon Films , 2004, Science.

[17]  K. Novoselov,et al.  A roadmap for graphene , 2012, Nature.

[18]  Stabilization of planar tetracoordinate carbon , 1976 .

[19]  J. Rocca,et al.  Experimental and theoretical study of neutral AlmCn and AlmCnHx clusters. , 2010, Physical chemistry chemical physics : PCCP.

[20]  Xiaojun Wu,et al.  AlxC Monolayer Sheets: Two-Dimensional Networks with Planar Tetracoordinate Carbon and Potential Applications as Donor Materials in Solar Cell. , 2014, Journal of Physical Chemistry Letters.

[21]  Zhongfang Chen,et al.  A bifunctional strategy towards experimentally (synthetically) attainable molecules with planar tetracoordinate carbons. , 2010, Physical chemistry chemical physics : PCCP.

[22]  Yi‐hong Ding,et al.  Design of sandwichlike complexes based on the planar tetracoordinate carbon unit CAl4(2-). , 2007, Journal of the American Chemical Society.

[23]  Isaiah Shavitt,et al.  Is the stereomutation of methane possible? , 1995, J. Comput. Chem..

[24]  J. Simons,et al.  Tetracoordinated Planar Carbon in the Al4C- Anion. A Combined Photoelectron Spectroscopy and ab Initio Study , 1999 .

[25]  Hui Wang,et al.  Substitutional alloy of Bi and Te at high pressure. , 2011, Physical review letters.

[26]  Xiaojun Wu,et al.  Exploration of Structures of Two-Dimensional Boron-Silicon Compounds with sp(2) Silicon. , 2013, The journal of physical chemistry letters.

[27]  Xiaojun Wu,et al.  Predicting two-dimensional boron-carbon compounds by the global optimization method. , 2011, Journal of the American Chemical Society.

[28]  Kresse,et al.  Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. , 1996, Physical review. B, Condensed matter.

[29]  Thomas Heine,et al.  Recent advances in planar tetracoordinate carbon chemistry , 2007, J. Comput. Chem..

[30]  Hui Wang,et al.  Predicted lithium-boron compounds under high pressure. , 2012, Journal of the American Chemical Society.

[31]  S. Iijima.  Helical microtubules of graphitic carbon , 1991, Nature.

[32]  Roald Hoffmann,et al.  Planar tetracoordinate carbon , 1970 .

[33]  Zhi‐Xiang Wang,et al.  Planar hypercoordinate carbons joined: wheel-shaped molecules with C-C axles. , 2002, Angewandte Chemie.

[34]  P. Schleyer,et al.  Planar pentacoordinate carbon in CAl5(+): a global minimum. , 2008, Journal of the American Chemical Society.

[35]  B. Delley.  From molecules to solids with the DMol3 approach , 2000 .

[36]  J. Simons,et al.  Experimental Observation of Pentaatomic Tetracoordinate Planar Carbon-Containing Molecules , 2000 .

[37]  P. Schleyer,et al.  Planar and inherently non-tetrahedral tetracoordinate carbon: a status report * , 1995 .

[38]  Daoben Zhu,et al.  Architecture of graphdiyne nanoscale films. , 2010, Chemical communications.

[39]  Z. Cao,et al.  Zigzag boron-carbon nanotubes with quasi-planar tetracoordinate carbons. , 2008, Journal of the American Chemical Society.

[40]  L. Radom,et al.  The planar carbon story , 1998 .

[41]  Xiaojun Wu,et al.  Two-dimensional boron monolayer sheets. , 2012, ACS nano.

[42]  Hiroyuki Kawai,et al.  Experimental evidence for epitaxial silicene on diboride thin films. , 2012, Physical review letters.

[43]  Qing Tang,et al.  Graphene-related nanomaterials: tuning properties by functionalization. , 2013, Nanoscale.

[44]  Warren J. Hehre,et al.  AB INITIO Molecular Orbital Theory , 1986 .

[45]  Yanming Ma,et al.  Global structural optimization of tungsten borides. , 2013, Physical review letters.

[46]  Xiaojun Wu,et al.  B2C graphene, nanotubes, and nanoribbons. , 2009, Nano letters.

[47]  R. Hoffmann,et al.  Planar tetracoordinate carbon in extended systems. , 2004, Journal of the American Chemical Society.

[48]  P. Schleyer,et al.  Planar tetracoordinate carbon atoms centered in bare four-membered rings of late transition metals. , 2006, Inorganic chemistry.

[49]  Yanming Ma,et al.  Spiral chain O4 form of dense oxygen , 2011, Proceedings of the National Academy of Sciences.

[50]  T. Ichihashi,et al.  Single-shell carbon nanotubes of 1-nm diameter , 1993, Nature.

[51]  S. C. O'brien,et al.  C60: Buckminsterfullerene , 1985, Nature.

[52]  Zhongfang Chen,et al.  SiC2 silagraphene and its one-dimensional derivatives: where planar tetracoordinate silicon happens. , 2011, Journal of the American Chemical Society.

[53]  K. Exner,et al.  Planar hexacoordinate carbon: a viable possibility. , 2000, Science.

[54]  B. Delley.  An all‐electron numerical method for solving the local density functional for polyatomic molecules , 1990 .

[55]  Jannik C. Meyer,et al.  Imaging and dynamics of light atoms and molecules on graphene , 2008, Nature.

[56]  Zhongfang Chen,et al.  Planar tetracoordinate carbon species involving beryllium substituents. , 2008, Inorganic chemistry.

[57]  J. Simons,et al.  TETRACOORDINATED PLANAR CARBON IN PENTAATOMIC MOLECULES , 1998 .

[58]  F. Weinhold,et al.  Natural population analysis , 1985 .

[59]  Zhongfang Chen,et al.  Be(2)C monolayer with quasi-planar hexacoordinate carbons: a global minimum structure. , 2014, Angewandte Chemie.

[60]  Gustavo E. Scuseria,et al.  Erratum: “Hybrid functionals based on a screened Coulomb potential” [J. Chem. Phys. 118, 8207 (2003)] , 2006 .

[61]  C. Jin,et al.  Deriving carbon atomic chains from graphene. , 2009, Physical review letters.

[62]  X. Zeng,et al.  Polymorphic phases of sp3-hybridized carbon under cold compression. , 2012, Journal of the American Chemical Society.

[63]  Yanming Ma,et al.  An effective structure prediction method for layered materials based on 2D particle swarm optimization algorithm. , 2012, The Journal of chemical physics.

[64]  Yan-Bo Wu,et al.  Simplest neutral singlet C2E4 (E = Al, Ga, In, and Tl) global minima with double planar tetracoordinate carbons: equivalence of C2 moieties in C2E4 to carbon centers in CAl4(2-) and CAl5(+). , 2009, The journal of physical chemistry. A.

[65]  Yanchao Wang,et al.  Crystal structure prediction via particle-swarm optimization , 2010 .

[66]  X. Zeng,et al.  Probing the planar tetra-, penta-, and hexacoordinate carbon in carbon-boron mixed clusters. , 2008, Journal of the American Chemical Society.

[67]  Burke,et al.  Generalized Gradient Approximation Made Simple. , 1996, Physical review letters.

[68]  M. S. Singh,et al.  All-electron local-density and generalized-gradient calculations of the structural properties of semiconductors. , 1994, Physical review. B, Condensed matter.

[69]  F. Cotton,et al.  The probable existence of a triple bond between two vanadium atoms , 1977 .

[70]  Lai‐Sheng Wang,et al.  Beyond Classical Stoichiometry: Experiment and Theory , 2001 .