SCF convergence issue with GAPW and all electron basis

[Hengyuan Shen]

Dear CP2K community,

I tried to calculate the XPS binding energy of some O atoms on a Pt surface. I used a big all electron basis for the interested O atoms, a smaller all electron basis for other O atoms, and GTH-MOLOPT basis for Pt with pseudopotential. However, the SCF calculation could not converge. I then tried the ground state calculation with a similar GPAW method and GPW method. For GPAW method, the SCF convergence also failed, and gave me an absurd energy. The GPW method converged after about 100 steps. Strangely, both calculations showed warnings about Fermi-Dirac smearing, although I used METHFESSEL_PAXTON smearing and 1000 ADDED_MO. Any idea on this issue? Any suggestions would be appreciated. Thank you.

Best regards,

Hengyuan

[Marcella Iannuzzi]

Dear Hengyuan,

The smearing method that you are using is obviously not working properly, also in the case of GPW.

It is not normal that the occupation is smeared down to the first MO.  You can add as many added MOs as you want, this does not change.

 *** WARNING in qs_mo_occupation.F:121 :: Fermi-Dirac smearing includes ***

 *** the first MO

Indications of a wrong behaviour are also the oscillating convergence  and the non-zero total charge density 

  Total charge density on r-space grids:       -0.0006221769

  Total charge density g-space grids:          -0.0006221769

My suggestion is to run the GPW calculation with the Fermi-Dirac smearing to confirm that one problem is the choice of the smearing method. 

Regards

Marcella