structures.m

Go to the documentation of this file.

%%    Eotvos Quantum Transport Utilities - structures
%    Copyright (C) 2009-2015 Peter Rakyta, Ph.D.
%
%    This program is free software: you can redistribute it and/or modify
%    it under the terms of the GNU General Public License as published by
%    the Free Software Foundation, either version 3 of the License, or
%    (at your option) any later version.
%
%    This program is distributed in the hope that it will be useful,
%    but WITHOUT ANY WARRANTY; without even the implied warranty of
%    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
%    GNU General Public License for more details.
%
%    You should have received a copy of the GNU General Public License
%    along with this program.  If not, see http://www.gnu.org/licenses/.
%
%    This function creates a data structure used by EQuUs. (since EQuUs v4.5)
%%
function ret = structures( name )

if strcmp( name, 'hole')
     %> Structure hole contains the data about the antidot used in class antidot
     ret = struct( ... name: hole
     ... %> An instance of structure @coordinates containing the coordinates of the center. 
     'center', [], ... type: coordinates
     ... %> The radius of the hole in the units of the lattice constant. 
     'radius',[] ...
     );   

     ret.center = structures('coordinates');
    
elseif strcmp( name, 'circle')
     %> Structure circle contains data describing a circle shaped area positioned in a two-dimensional space
     ret = struct( ... name: circle
     ... %> An instance of structure @coordinates containing the coordinates of the center. 
     'center', [], ... type: coordinates
     ... %> The radius of the circle . 
     'radius',[] ...
     );   

     ret.center = structures('coordinates');    

elseif strcmp( name, 'param')
     %> Structure param contains data structures describing the physical parameters of the scattering center and the leads.
     ret = struct( ... name: param
     ... %> An instance of the structure @scatter_param containing the physical parameters for the scattering region. 
     'scatter',[], ...type: scatter_param
     ... %> A list of structures @lead_param containing the physical parameters for the scattering region. 
     'Leads',[] ... type: lead_param
     );

elseif strcmp( name, 'scatter_param') %NEW vargamma2
     ret = struct();

elseif strcmp( name, 'lead_param') 
     ret = struct();

elseif strcmp( name, 'Opt')
     %> Structure Opt contains the basic computational parameters used in EQuUs
     ret = struct( ... name: Opt
     ... %> Set 1 in order to supress output messages. 
     'Silent', true,... 
     ... %> Set 1 to use the Bogoliubov de Gennes model, 0 (default) for normal systems.
     'BdG',[],...
     ... %> Obsolete parameter
     'Just_Create_Hamiltonians',[],...
     ... %> Set true if a magnetic field is involved in the calculations, false (default) otherwise. 
     'magnetic_field',[],...
     ... %> Set true (default) if a magnetic field is translational invariant along the scattering center, or false otherwise. 
     'magnetic_field_trans_invariant',[],...    
    ... %> String containining a bult-in vector potential. Possible values are: 'LandauX', 'LandauY'
     'gauge',[],...  
    ... %> Scalar value representing the strength of the bult-in vector potential: \f$ \eta = ea^2B/\hbar \f$ with \f$a\f$ standing for the atom-atom distance.
     'eta',[],...      
     ... %> Set 1 to use linear interpolation for the vector potential between the atomic sites to calculate the Peierls phases. Useful when dealing with a homogeneous magnetic field. 
     'Linear_Regression_in_B',[],...
     ... %> Set 1 if a simple analytical surface greens function computational method is about to be used, 0 otherwise (Only for square lattice without magnetic field). 
     'Simple_Green_Function',[],...
     ... %> String describing the preprogrammed lattice type. See the documentation of lattice types for details
     'Lattice_Type',[], ...
     ... %> Number of leads attached to the scattering region. 
     'NofLeads',[],...
     ... %> Obsolete parameter
     'Decimate_only_Dyson',[],...
     ... %> The maximal number of the sites to be decimated at once. 
     'Decimation_block',[],...
     ... %> Option for using decimation algorith. (see more details at the documenatation of class Decimation) 
     'Decimation',[],...
     ... %> Set 1 to use dual modes in the calculations, or 0 to use the left and right sided eigenvectors instead. 
     'usingDualModes',[], ... 
     ... %> Set 1 to export debug informations into the debug.txt file, or 0 otherwise. 
     'debug', [],...
     ... %> Number of workers in the parallel pool. 
     'workers', [], ...
     ... %> Set 'siesta' to import Hamiltonians from Siesta, 'custom' to use custom defined Hamiltonians. 
     'custom_Hamiltonians', [],...
     ... %> Set 1 to use 1/2 spin degree of freedom in the Hamiltonians, or 0 otherwise. 
     'Spin', []...
     ); 

elseif strcmp( name, 'coordinates')
     ret = Coordinates();

elseif strcmp( name, 'shape')
     %> Structure shape contains data about the geometry of the scattering region.
     ret = struct( ... name: shape
     ... %> The number of sites in the cross section. 
     'width',[],...
     ... %> Number of unit cells along the logitudinal direction in the scattering region. 
     'height',[] ...
     );

elseif strcmp( name, 'scatterers')
     %> Structure scatterers contains data on the scattering impurities used in class antidot
     ret = struct( ... name: scatterers
     ... %>  A vector of slab indexes in the ribbon. 
     'z',[],...
     ... %>  A vector of site indexes in the slabs. 
     'zpoints',[],...
     ... %>  A vector of the on-site potentials. 
     'potentials',[],...
     ... %>  A vector of the site indexes
     'siteindexes',[],...
     ... %>  Set true if the given sites are about to remove from the lattice. 
     'aremissing',[]...
     );

elseif strcmp( name, 'BandWidth')
     %> Structure BandWidth describes the bandwidth in the lead and in the scattering center.
     ret = struct( ... name: BandWidth
     ... %> An instance of the structure @BandWidthLimits for the lead. 
     'Lead',[],...
     ... %>  An instance of the structure @BandWidthLimits for the scattering region. 
     'Scatter',[]...
     );

elseif strcmp( name, 'BandWidthLimits')
     %> Structure BandWidthLimits contains the bandwidth limits.
     ret = struct( ... name: BandWidthLimits
     ... %>  The minimal value of the energy band. 
     'Emin',[],...
     ... %>  The maximal value of the energy band. 
     'Emax',[]...
     );
    
elseif strcmp( name, 'Atom') 
     %> Structure Atom contains the atomic identifiers of the sites.
     ret = struct( ... name: Atom
     ... %>  Identification number of the principal layer containing the atom. 
     'PL', [],... 
     ... %>  Identification number of the atom. 
     'Id', []...
     );  
     ret.PL = cell(0);
     ret.Id = cell(0);  
    
elseif strcmp( name, 'open_channels')
     %> Structure open_channels describes the open channel in the individual leads.
     ret = struct( ... name: open_channels
     ... %>  Number of open channels. 
     'num', [],...
     ... %>  Logical indexes of incoming electron-like channels. 
     'BdG_u_incoming', [],...
     ... %>  Logical indexes of outgoing electron-like channels. 
     'BdG_u_outgoing', [],...
     ... %>  true of the system is superconducting, false otherwise. 
     'isSuperconducting', [],...
     ... %>  Logical indexes of ingoing channels. 
     'open_channels_p', [],...
     ... %>  Logical indexes of outgoing channels. 
     'open_channels_m', []...
     );  
    
elseif strcmp( name, 'junction_sites')
     %> Structure junction_sites contains data to identify the individual sites of the leads, the interface regions and the scattering region in a matrix.
     ret = struct( ... name: junction_sites
     ... %>  Structure @sites describing the geometry of the leads. 
     'Leads', [],... type: sites
     ... %>  Structure @sites describing the geometry of the scattering region. 
     'Scatter', [],... type: sites
     ... %>  Structure @sites describing the geometry of the interface regions. 
     'Interface', []... type: sites
     );   
    
elseif strcmp( name, 'sites')
     %> Structure sites contains data to identify the individual sites in a matrix.
     ret = struct( ... name: sites
     ... %>  An instance of structure @coordinates describing the geometry. 
     'coordinates', [],...
     ... %> An array containing the site indexes of the given system part. 
     'site_indexes', []...
     );    
    
elseif strcmp( name, 'DOS')
     %> Structure containg the energy resolved density of states
     ret = struct( ... name: DOS
     ... %> Array of the density of states values
     'DOSvec', [],...
     ... %> Array of the enrgy points
     'Evec', [] ...
     );        

elseif strcmp( name, 'LocalDOS')
     %> Structure containg the local density of states at a given energy point
     ret = struct( ... name: LocalDOS
     ... %> Array of the density of states values
     'DOSvec', [],...
    ... %> A structure containing the coordinates of the sites
     'coordinates', structures('coordinates'),...
     ... %> The energy point
     'Energy', [] ...
     );        

elseif strcmp( name, 'WaveFnc') 
     %> Structure containg datat on the calculated eigenstate in a translational invariant lead.
     ret = struct( ... name: WaveFnc
    ... %> Cell array containing the individual wave functions.
          'WaveFnc', [], ...
    ... %> Cell array containing the individual k-pints.
          'ka', cell(length(ka_vec),1), ...
    ... %> Cell array containing the individual energies.
            'E', cell(length(ka_vec),1) ...
            );
    
else
    err = MException('structure:name', 'Unrecognized structure name');
    save('structure.mat');
    throw(err); 
end



end