% This program computes the Reciprocal lattice vectors Gvec that is needed in the

% epm model. According to Dragica Vasileska (Arizona Satae University), the reciprocal

% lattice vector up to and includingthe 10th-nearest neighbours are sufficient and correspond

% to 137 plane waves

% https://nanohub.org/resources/1524/download/empiricalpseudopotentialmethod_word.pdf

close all

clear all

clc

NN_neighbours=10;

ig2_mag=[0, 3, 4, 8, 11, 12, 16, 19, 20, 24];

ig2_mag=ig2_mag(1:NN_neighbours);

icount=0;

for i=1:NN_neighbours

ig2=ig2_mag(i);

ia=floor(sqrt(double(ig2)));

ic=0;

for i=-ia:ia

for j=-ia:ia

for k=-ia:ia

idx = i^2 + j^2 + k^2;

if (idx==ig2)

ic=ic+1;

gx(ic+icount)=i;

gy(ic+icount)=j;

gz(ic+icount)=k;

end

end

end

end

icount=icount+ic;

end

Gvec=[gx' gy' gz'];

size(Gvec)

save('Gvec.txt','Gvec')