[Pw_forum] calculating U

[Naol Regassa]

Dear all

I was calculating Hubbard U for strongly correlated perovskite like
SrMnO3. I can run scf and scf+u, perturbed for different
Hubbard_alpha. My question is

1- Do we check the convergence of alpha? If yes with what parameter?

 2- How do we find the value of U? What are the important parameter
there(in the perturbed outputs)?

3 - Is it needed to construct super cells so that we can check the
convergence with them?

great thanks for your response
Thesis student