def rgop_c3(i,spinindex):
r'''
get NRG operator $c_{i\sigma}c_{i\bar{\sigma}}^\dag c_{i\bar{\sigma}}$
'''
spaceconfig=SuperSpaceConfig([1,2,1,1])
f1=op_c(spaceconfig=spaceconfig,index=spinindex)()
f2=op_cdag(spaceconfig=spaceconfig,index=1-spinindex)()
fff=op_c(spaceconfig=spaceconfig,index=1-spinindex)()
FFF=f1.dot(f2.dot(fff)).view(OpArray)
FFF.label='fff%s%s'%(i,'up' if spinindex==0 else 'dn')
return op2expand(FFF,expansion_method='expand',starting_level=i+1)
def rgop_c(i,spinindex=0):
'''
get the c^dag operator for specific site.
i:
the site index.
spinindex:
the spin index.
'''
spaceconfig=SuperSpaceConfig([1,2,1,1])
fd=op_c(spaceconfig=spaceconfig,index=spinindex)().view(OpArray)
fd.label='f%s%s'%(i,'up' if spinindex==0 else 'dn')
return op2expand(fd,expansion_method='expand',starting_level=i+1)
def rgop_n(i,spinconfig='up'):
'''
number of i-th site.
i:
site index.
spinconfig:
the spin configuration, refer spindict for more detail.
'''
spaceconfig=SuperSpaceConfig([1,2,1,1])
n=0
for s1,s2,sfactor in spin_dict[spinconfig]:
opcd=op_cdag(spaceconfig=spaceconfig,index=s1)().view(OpArray)
opc=op_c(spaceconfig=spaceconfig,index=s2)().view(OpArray)
n=n+dot(opcd,opc)
n.label='n%s%s'%(i,spinconfig)
return op2expand(n,expansion_method='expand',starting_level=i+1)
