hi, in graphene the C atoms are in one plane...therefore it is sometimes called 2D material....z=0 for both C atoms... try to plot your crystal structure and you will see that you do not get the graphene honeycombe.... s.auluck
> Many thanks for the reply. It seems that the coordinates of Marcos is > true. > The coordinates are given in fractional cordinates and distance between > the two C atoms is ~1.42 Angstrom which is C-C distance in graphene. In > the > prevous post, the bandstructure of Charlier has been wrongly attached. > Again I am attaching the input and bandstructures. Sorry for the mistake > > On Mon, Sep 17, 2012 at 4:30 PM, Roland Gillen > <[email protected]>wrote: > >> Hi, >> >> you might want to check the coordinates of the second carbon atom. >> (0.3333, >> 0.3333, 0.3333) means that the z-coordinate of the second atom is ~8 >> Angstrom, while that of the first is 0 Ang. Marcos probably made a typo >> in that post you areusing as a reference and meant (0.3333, 0.3333, 0.0) >> instead of (0.3333, 0.3333, 0.3333). >> >> Roland >> >> >> >> On 17 September 2012 09:08, bedamani singh <[email protected]> wrote: >> >>> I am a new user of siesta and have been trying to find the >>> bandstructure >>> of graphene. >>> >>> As the correct selection of K-points in the first brilluion zone is a >>> prequisite for calculating the bandstructure. I am at loss as how to >>> find >>> the coordintes of K points in the reciprocal space. I have done >>> calculations from the reference ( >>> http://www.mail-archive.com/[email protected]/msg00935.html) with the >>> atomic positions at (0,0,0); (0.3333, 0.3333, 0.3333) in fractional >>> cordinates for C atoms and the lattice cell is used as >>> >>> LatticeConstant 2.44 Ang >>> >>> %block LatticeParameters >>> >>> 1.00 1.00 10.0 90.0 90.0 60.0 >>> >>> %endblock LatticeParameters >>> >>> Relaxation was done MD.VariableCell (.true.) and kgrid _Monkhorst_Pack >>> is used as >>> >>> %block kgrid_Monkhorst_Pack >>> >>> 6 0 0 0.0 >>> >>> 0 6 0 0.0 >>> >>> 0 0 1 0.0 >>> >>> %endblock kgrid_Monkhorst_Pack >>> >>> The coordinates of the Kpoints are calculated using a =1.42 angstrom in >>> the relations >>> >>> Gamma= (0,0,0) ; K= (2pi/a)(1/3,0,0) ; and M=(2pi/a)(1/3,1.732/9,0) and >>> used >>> >>> BandLinesScale pi/a >>> >>> %block bandlines >>> >>> 1 1.476 0.000 0.000 K >>> >>> 51 0.000 0.000 0.000 /Gamma >>> >>> 101 1.476 0.852 0.000 M >>> >>> %endblock bandlines >>> >>> I am tring to compare the observed bandstructure with those reported >>> by >>> J. C. Charlier et al. (See the attached pdf file)(" Electron and phonon >>> properties of graphene: their relationship with carbon nanotubes" >>> DOI:10.1007/978-3-540-72865-8_21). But the two results are not >>> matching. >>> The input fdf, my observed bandstructure and bandstructure of J. C. >>> Charlier et al. are attached. Anyone please help in finding the true >>> K-points. >>> >>> >> > ....................................................................... Prof. Sushil Auluck Phone:+91-512-6797092/6148 Department of Physics +91-512-6798177(Home) Indian Institute of Technology Cell :+91-9305548667 Kanpur 208016 (UP) Fax :+91-512-6790914 India E-mail:[email protected] ...............................................:[email protected] http://www.iitk.ac.in/phy/People/phy_facvis.html http://www.iitk.ac.in/phy/New01/profile_SA.html ....................................................................... ~
