confusing example in README.md

[oroszl]

Let me just start by saying that I RALLY like the package, nice interface to DMRG!

I think the example "Spin and charge correlator of the 1D Hubbard model " in the README.md has some typos. specifically, I think it should be I noted corrections with NOTE

from dmrgpy import fermionchain
n = 20 # number of sites
fc = fermionchain.Spinful_Fermionic_Chain(n)
# first neighbor hopping
h = 0
for i in range(n-1):
  h = h+fc.Cdagup[i]*fc.Cup[i+1]            # NOTE  h = h+... instead just h = ...
  h = h+fc.Cdagdn[i]*fc.Cdn[i+1]
h = h.get_dagger() # Make Hermitian
# Hubbard term
for i in range(n):  # NOTE  range should go for all sites
  h = 2.*(fc.Nup[i]-.5)*(fc.Ndn[i]-.5)    # NOTE Ndn instead of Cup[i+1]
fc.set_hamiltonian(h) # initialize the Hamiltonian
pairs = [(0,i) for i in range(n)]
# compute the two correlators
zz = [fc,vev(fc.Sz[0]*fc.Sz[i]).real for i in range(n)]
cc = [fc,vev(fc.Cdagup[0]*fc.Cup[i]).real for i in range(n)]
print("Spin correlators",zz)
print("Site correlators",cc)

Am I correct? I was not sure if this warranted a pull request.. :)

[joselado]

Fixed, thanks!

[oroszl]

I forgot this one h = h.get_dagger() # Make Hermitian this should be h = h + h.get_dagger() # Make Hermitian

[joselado]

Thanks a lot! I also fixed that one.