[Wien] Band gap using HF potential

[tran at theochem.tuwien.ac.at]

>1. When I run the command init_hf_lapw, Should I put same number of k-points in fbz which I used during init_lapw?

This is not required. However, if a GGA calculation is done before
init_hf_lapw (during which the chosen k-mesh may be another one),
then you have to execute clean_lapw in order to delete the vector
file (otherwise the HF calculation will crash).

>2. Can I calculate band gap of semiconducting compounds using reduced k-mesh in hf potential?

Yes

>3. What precautions should I use during running hf potential?

Do the very first calculation with low parameters (number of k-points,
basis set size, etc.) in order to have an idea of the computational
time.

>4. Is there any need to converge the values of alpha, Lambda, gmax, lmaxe & lmaxv in case.inhf file? If yes, then what will be the procedure?

alpha and lambda are not convergence parameters, but they define the
functional (see literature).

gmax, lmaxe and lmaxv are convergence parameters.
gmax=8, lmaxe=4, and lmaxv=4 should be converged values in most cases,
but they may lead to calculations that are too expensive.