def plot_band(alpha,Vz,Delta,t=1.,mu=0.,nsite=100):
'''
show the meanfield band.
'''
model=RashbaModel(U=0.,alpha=alpha,Vz=Vz,Delta=Delta,t=t,mu=mu,nsite=nsite,periodic=True,kspace=True)
hgen=model.hgen
kl=hgen.kspace.kmesh-pi
hkmesh=hgen.gethkmesh(kl)
hmesh=Hmesh(hkmesh)
print hmesh.check_hermicity()
ekmesh=hmesh.getemesh()
LABELSIZE=14
ion()
fig=figure(figsize=(7,5))
plot(kl[:,0],ekmesh)
if True:#hgen.spaceconfig.nnambu==1:
axhline(y=0,ls='--',color='k')
text(1.8,-0.1,'$\mu=0$',ha='center',va='center',fontsize=14)
if Vz==0 and alpha!=0:
dy=alpha**2/2
annotate('',xy=(-alpha,-2*dy),xycoords='data',xytext=(alpha,-2*dy),\
arrowprops=dict(arrowstyle='<->',shrinkA=0,shrinkB=0))
plot([-alpha,-alpha],[-dy-0.1,-dy+0.1],color='k',ls='-')
plot([alpha,alpha],[-dy-0.1,-dy+0.1],color='k',ls='-')
text(0,-2*dy-0.1,r'$2\alpha$',va='center',ha='center',fontsize=14)
xlabel(r'$k$',fontsize=LABELSIZE)
ylabel('Energy($t$)')
xlim(-pi,pi)
xticks([-pi,0,pi],[r'$-\pi/a$','0',r'$-\pi/a$'],fontsize=14)
tight_layout()
pdb.set_trace()
savefig('data/band_%s.png'%model.get_str())
def plot_band(delta=0.1,t=1.,mu=0.,nsite=100):
'''
show the meanfield band.
'''
model=SSHModel(t=t,mu=mu,delta=delta,nsite=nsite,periodic=True,kspace=True)
hgen=model.hgen
kl=hgen.kspace.kmesh-pi
hkmesh=hgen.gethkmesh(kl)
hmesh=Hmesh(hkmesh)
print hmesh.check_hermicity()
ekmesh=hmesh.getemesh()
ion()
plot(kl[:,0],ekmesh)
pdb.set_trace()
