vvitale / graphene

Graphene model screening + tight-binding

Graphene model screening + tight-binding

Author

Fabiano Corsetti, Imperial College London, UK

• Email: fabiano.corsetti08 {at} imperial.ac.uk
• Homepage: http://www.cmth.ph.ic.ac.uk/people/f.corsetti/

Description

This code compiles three separate executables, screening.x, TB.x, and adatom_post.x. screening.x is a serial program which calculates the model screened potential for Coulomb charges on graphene and the symmetries of the supercell. TB.x is a parallel program for performing a tight-binding simulation of the system. adatom_post.x is a serial program for post- processing the output of the tight-binding simulation for the case of a single adatom at the origin of an n x n supercell.

Installation

1. Copy make.inc.example to make.inc and modify it to suit your needs. In particular, you will need to provide a Fortran compiler (MPI-enabled for TB.x) and the following libraries:

   • Spglib for crystal symmetries (only needed for screening.x)
   • FFTW3 for FFTs (only needed for screening.x)
   • BLAS+LAPACK+ScaLAPACK for linear algebra (only needed for TB.x)

   The example provided will work on the cmth cluster after loading the following modules:

   • intel-suite/2015.3.187
   • openmpi/1.10.2
   • mkl/2015.3.187
   • fftw/3.3.4
   • spglib/1.9.8-20-gb63ea50

2. Type make to compile both codes. Alternatively use make screening to only compile screening.x, make TB to only compile TB.x, or make adatom_post to only compile adatom_post.x.

Usage

• screening.x:

  • Run as: ./screening.x
  • Input: The program reads a single text file called screening.in. An example is provided in the example directory. All variables must be present in the given order. An explanation for each variable is given in the example. The input file specifies the dimensions of the supercell, the impurity Coulomb charges providing the bare external potential, the specifications of the screening model to use, and the k-point mesh to calculate.
  • Output: The screened potential is written to potential.dat. Additional info for the tight-binding code is written to weights* (atomic site info), kweights* (k-point info), and sym_ops* (symmetry operations info, only present if k-point symmetry is calculated).

• TB.x:

  • Run as: mpirun -np * ./TB.x
  • Input: The program requires all the output files produced by screening.x, and reads a text file called TB.in. An example is provided in the example directory. All variables must be present in the given order; note however that the sym_ops* filename line is only present if the file is present. An explanation for each variable is given in the example. The input file specifies the dimensions of the supercell, physical parameters used in the simulation, the names of the additional input files produced by screening.x, and some information necessary for the parallel linear algebra routines.
  • Output: The total DOS is written to dos.dat, and the LDOS of each site to ldos.*.dat. The electronic density is written to density.dat. Note that both the LDOS and density are only written for symmetrically non-equivalent sites (as specified in the weights* file).

• adatom_post.x:

  • Run as: ./adatom_post.x
  • Input: The program reads both the TB.in input file used by TB.x and the ldos.*.dat and density.dat output files it has produced. It also reads the weights* file from screening.x. No further input is needed.
  • Output: The radially-averaged DOS is written to rdos.*.dat, and the radially-averaged electronic density is written to rdensity.dat.

License

Copyright © 2016, Fabiano Corsetti

All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.