increasing ENCUT and wrong results

[asiyeh_shokri2]

Hello,

I am new in VASP, I want to do relaxation calculations for Ga2O3. As much as I know for relaxation calcs we need to optimize encut and kpoint. I have done these parts and using encut=750 I get a wrong lattice parameter and band gap comparing with literature. and when I do not set the encut (as I see the default is equal to ENMAX in POTCAR) I get the correct bandgap!
I am sending my INCAR file and appreciate any help.
###################INCAR FILE
PREC=Accurate
EDIFF=1e-6
EDIFFG=1e-2
NSW=200
ISIF=3
ENCUT = 400
IBRION=2
POTIM=0.5
ISMEAR=1
SIGMA=0.1

[ferenc_karsai]

Compared to which literature? Theory or experiment? Theoretical results using the same functional, potentials and parameters should be very well reproducible with high enough ENCUT (at least for the major codes).
Your result with ENCUT=400 is most likely not the converged result and only by arbitrarily agrees with your target.
If for converged ENCUT and k-mesh you don't agree with previous calculations then some of the other parameters must disagree:
Bravais lattice, Wycoff positions, exc functional, etc.

There are many parameters and you need to compare all.

Experiment depends on your functional, so experimental reproducability by theory is very often not possible.

[asiyeh_shokri2]

Thanks to your answer. There are articles reported with VASP. And they used ENCUT=400 and the same Bravais lattice and their result is completly different from mine and are so close to the experimental results. Sure, I will examin every parameters.

Regards