Hello all,

I am trying to calculate the positron annihilation momentum distribution spectrum produced by a vacancy. The input file in the tutorial uses `istwfk *1`

. After trying this, I found that this parameter severely affects the convergence of the SCF cycle. With all other parameters exactly the same, using the default value of `istwfk`

can complete the GS calculation within no more than 100 SCF cycles, but using `istwfk *1`

causes the total energy obtained from each SCF cycle to fluctuate dramatically, with no sign of convergence at all.

Is this normal? Do I need to use a higher `ecut`

and `nkpt`

to compensate for this?

And, what is the purpose of using `istwfk *1`

to deactivate time-reversal symmetry in the above tutorial? If it is to get a uniform k-point grid in the momentum space, is that parameter still important if I only use the gamma point?

Thanks!