Dear Peter,
I would suggest for checking pw.x the option
diagonalization='cg', in this way a conjugate-gradient
algorithm is used for finding the ground-state of the
KS-Hamiltonian, instead of the 'davidson' algorithm.
It will be slower but maybe more stable.
The main difference between the cp.x
Dear Peter,
If you have to deal with large systems in a supercell
sampled only at the gamma point, you could perform
ionic relaxation using the CPV code cp.x.
For this task you should peform a damped molecular dynamics,
using either a Car-Parrinello or a Born-Oppenheimer
scheme, (the latter should
