Problems with Energy Convergence

[cdt9f]

Hi,

I am running a "simple" single-point calculation on a 7 layer 1x1 Pt(111) slab with an approximately equal amount of vacuum. I am using 11x11x1 kpoints, PW91 and ultrasoft pseuodpotls.

The problem I am having is that the energy is not converging. For the first 11 cycles or so everything is fine (i.e. the energy quickly approaches the right order of magnitude, a few tens of eV's), but then the energies jump up to the MeV scale and fluctuate by keV. After 800 scf iterations the energy is still jumping by keV!!

I have tried playing with mixing (default settings versus imix=0), and the algorithm (ialgo=48, versus algo=fast, algo=All). I didn't have this problem using an older version of vasp (4.4.5) but I do on the newer version 4.6.27.

Any help on this problem would be appreciated.

Thanks,
Christopher Taylor
Grad Research Assistant
Univ of Virginia

[cdt9f]

Just for the record, setting ISYM=0 seems to have solved the problem.

Chris