Drawing Band Structure of Silicene Under Strain Using Tight Binding Methods

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In summary: And in summary, the code provided is a corrected MATLAB code for drawing a band structure of silicene under strain using tight binding methods. It includes calculations for changing K points under strain and also incorporates corrections for plotting.
  • #1
anahita
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I have been drawing band structure silicene under strain using tight binding methods.
How to change K points under strain?
Matlab code is corrected?[
MATLAB code for the intended purpose as follows:
Code:
close all
clear all
clc
Na=2; % Number of atoms
Nbnd=8; % number of bands
q=0.1;
w=0.30;
aa=2.25*(1+q);
a=3.82*(1+q);
Csoc=0.3500;
EL=0;
POSx(1)=aa*cosd(30);
POSy(1)=aa*sind(30);
POSz(1)=-0.22;
POSx(2)=2*aa*cosd(30);
POSy(2)=2*aa*sind(30);
POSz(2)=0.22;
a1x=a;
a1y=0;
a2x=a*cosd(60);
a2y=a*sind(60);

sho=0;
for is=[0,-1,1]
  for js=[0,-1,1]
  for ks=1:Na
  sho=sho+1;
  X(sho)=POSx(ks)+is*a1x+js*a2x;
  Y(sho)=POSy(ks)+is*a1y+js*a2y;
  Z(sho)=POSz(ks);
  Ax(sho)=is*a1x+js*a2x;  % Vector for uint cell
  Ay(sho)=is*a1y+js*a2y;
  No(sho)=ks;
  L0=sqrt(((POSx(2)-POSx(1))^2+(POSy(2)-POSy(1))^2+(POSz(2)-POSz(1))^2));
  end
  end
end
figure(1)
plot(X,Y,'*')
Ax=Ax/a;
Ay=Ay/a;
fid = fopen('k.txt', 'r');
KP = fscanf(fid, '%g %g', [3 inf]);
KP = KP';
fclose(fid);

kx=(2*pi/2)*KP(:,1);
ky=(2*pi/2)*KP(:,2);

for ik=1:48
H=H0(Nbnd);
for ie=1:4
  H(ie,ie)=H(ie,ie)+POSz(1)*EL;
end
for ie=5:8
  H(ie,ie)=H(ie,ie)+POSz(2)*EL;
end

HSOC=zeros(2*Nbnd);

for is=1:Na
  for js=1:sho
  dis=sqrt(((X(is)-X(js))^2)+((Y(is)-Y(js))^2)+((Z(is)-Z(js))^2));
  if abs(dis-L0)<0.1 & abs(No(is)-No(js))>0
  l=(X(is)-X(js))/dis;
  m=(Y(is)-Y(js))/dis;
  n=(Z(is)-Z(js))/dis;
  if No(is)==1 & No(js)==2
  h1=hamiltonian1(l,m,n);
  h2=hamiltonian2(l,m,n);
  H(1:4,5:8)=H(1:4,5:8)+h1*exp(2i*((kx(ik)*Ax(js)+ky(ik)*Ay(js))))+h2*exp(2i*((kx(ik)*Ax(js)+ky(ik)*Ay(js))));
  end
  if No(is)==2 & No(js)==1
  h1=hamiltonian1(-l,-m,-n);
  h2=hamiltonian2(-l,-m,-n);
  H(5:8,1:4)=H(5:8,1:4)+h1'*exp(2i*((ky(ik)*Ay(js)+kx(ik)*Ax(js))))+h2'*exp(2i*((kx(ik)*Ax(js)+ky(ik)*Ay(js))));
  end
 
  end
  end
  h=pSOC(Nbnd);
  HSOC((is-1)*8+1:is*8,(is-1)*8+1:is*8)=Csoc*h; 
 
end

for ii=1:Nbnd
  for jj=1:Nbnd
  H2(2*ii-1:2*ii,2*jj-1:2*jj)=H(ii,jj)*eye(2);
  end
endE(ik,1:Nbnd)=sort(real(eig(H)));
Ep(ik,1:2*Nbnd)=sort(real(eig(H2+HSOC)));
pl(ik)=(ik-1)/34.4615;
endfor ip=1:8
  plot(pl,(E(:,ip)),'.b')
  hold all
end
hold all
for ik=1:48
for ib=1:Nbnd
  a=Ep(ik,2*ib-1);
  b=Ep(ik,2*ib);
  E1(ik,ib)=max(a,b);
  E2(ik,ib)=min(a,b);
end
end
E1(:,1:Nbnd)=Ep(:,1:2:2*Nbnd);
E2(:,1:Nbnd)=Ep(:,2:2:2*Nbnd);
figure
for ip=1:8
  plot(pl,real(E1(:,ip)),'.b')
  plot(pl,real(E1(:,ip)),'.b')
  hold all
  plot(pl,real(E2(:,ip)),'.b')
  plot(pl,real(E2(:,ip)),'.b')
end
 
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  • #2
hold allxlabel('K-Points')ylabel('Band Structure')title('Silicene Under strain')function h1=hamiltonian1(l,m,n)h1=[0.5*(1+l^2+m^2+n^2), 0.5*(-l^2+m^2+n^2), 0.5*(-l^2-m^2+n^2), -l*m*(1-n^2); 0.5*(-l^2+m^2+n^2), 0.5*(1+l^2-m^2-n^2), -l*m*(1-n^2), 0.5*(-l^2-m^2+n^2); 0.5*(-l^2-m^2+n^2), -l*m*(1-n^2), 0.5*(1+l^2+m^2-n^2), 0.5*(-l^2+m^2+n^2);-l*m*(1-n^2), 0.5*(-l^2-m^2+n^2), 0.5*(-l^2+m^2+n^2), 0.5*(1+l^2-m^2-n^2)];endfunction h2=hamiltonian2(l,m,n)h2=[0.5*(-l^2+m^2-n^2), -l*m*(1+n^2), 0.5*(-l^2-m^2-n^2), 0.5*(1-l^2+m^2+n^2); -l*m*(1+n^2), 0.5*(1-l^2-m^2+n^2), 0.5*(-l^2+m^2-n^2), 0.5*(-l^2-m^2-n^2); 0.5*(-l^2-m^2-n^2), 0.5*(-l^2+m^2
 

1. What is Silicene?

Silicene is a single-atom-thick layer of silicon atoms arranged in a honeycomb lattice, similar to graphene. It is a two-dimensional material that has gained attention for its potential use in electronics and other applications due to its unique properties.

2. What is the band structure of Silicene?

The band structure of Silicene refers to the distribution of energy levels for electrons in the material. It is a key property that determines the material's electronic and optical properties.

3. How does strain affect the band structure of Silicene?

Strain, or the deformation of a material, can significantly alter the band structure of Silicene. It can cause changes in the energy levels and band gaps, which can impact the material's properties and potential applications.

4. What is the tight binding method used for drawing the band structure of Silicene under strain?

The tight binding method is a mathematical approach used to calculate the electronic structure of a material. It involves constructing a simplified model of the material's atomic structure and solving for the energy levels of the electrons using quantum mechanics principles.

5. What are the potential applications of understanding the band structure of Silicene under strain?

Understanding the band structure of Silicene under strain can provide insight into how the material may behave in different environments or under different conditions. This knowledge can inform the design and development of new electronic devices, sensors, and other technologies that utilize Silicene's unique properties.

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