[Pw_forum] 3rd Order Properties and GGA's

[John Kendrick]

Dear All,

I have recently been looking at calculating Raman scattering intensities
at q=0 for organic crystals.  I was aware that ultra soft potentials are
not supported for the calculation of 3rd order properties.  I recently
tried out the CVS version of Quantum Espresso and discovered that there
is a check in phq_setup.f90 that aborts the calculation if the density
functional is a GGA.  No such check exists in 4.0.1.

I had a look at the manual and wiki, but I can't find this restriction
described anywhere.  Could someone let me know what the current
restrictions are on the calculation of Raman scattering intensities at q=0?

Thanks for your help.

John Kendrick