Dear Paolo Giannozzi, Thanks for your reply. I just looked at bands.f90. The purpose of bands.f90 is to check the band correspondence by taking inner product of (n,k) and (n',k') states in one structure. But what I would like to do is to taking inner product of (n,k) from one structure and (n',k') from another perturbed structure. Thus I need to read two set of wavefunction at the same time. Do you have suggestions to deal with this situation? Thank you!
>it depends upon what exactly you need. You may try to take >inspiration from code PP/bands.f90, which does something similar Xuhui Luo University of Illinois at Chicago and NIST
