[Pw_forum] Access to 2nd order derivatives

[Marcel Mohr]

Dear all,

I wonder if it is possible to obtain the 2nd derivative of the total 
energy for a user defined set of atomic coordinates (not a real but 
infinetively small displacement from the ground state).
This is what must be done in ph.x but for the phonon modes, or 
displacements.

Thanks in advance
Marcel