Dear All,
I obtained a positive total energy when using the Ag-sv-GW POTCAR for Ag system; however, this was not the case with the Ag-PBE and Ag-GW POTCARs.
Could you please check why this happened?
Many thanks in advance,
Ibrahim
I can confirm that the positive total energy exists. It is a bit larger than I would expect to see for these systems. However, absolute energies are meaningless with a pseudopotential method. The only important quantity are relative energies. To get these, I computed the bare atom by just removing the last three atoms from your structure. It turns out that this energy is also positive for the problematic POTCAR.
Code: Select all
POTCAR energy-atom energy-cluster 4*atom-cluster
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PAW_PBE Ag -0.03877022 -5.43378560 5.27870471
PAW_PBE Ag_GW -0.03846161 -5.44581400 5.29196758
PAW_PBE Ag_sv_GW 2.02465203 2.80553583 5.29307220
So the energy differences are fine. The softer PAW has a bit larger difference but the two GW potentials yield more or less the same energy.
Btw, if you set all MAGMOM to 0 it is better to calculate with ISPIN=1. This leads to faster calculations and faster convergence.