Screened Exchange LDA for GaN bulk

[diallois2]

Hello. I am trying to compute simple lattice constants for bulk GaN using sX-LDA but I keep having this error tag before my first ionic relaxation step:

"Stress not implemented
Stress not implemented
Stress not implemented
Stress not implemented
Stress not implemented
Stress not implemented
Stress not implemented"

I am a lot more experienced using HSE06 and it appears that this error is probably related to Pulay stresses. I have increased my cutoff energy and the precision -tag but nothing seems to work so far. Here are some of my INCAR parameters for the sx-LDA calculation:

LHFCALC = .TRUE. !Hybrid functionals
LTHOMAS = .TRUE. ; HFSCREEN = 1.8 ! standard Thomas-Fermi(TF) wavevector length for semiconductors
AEXX = 1.0 ! amount of exact exchange different than 0.25 in regular HSE03 HSE06
ALDAC = 1.0 ! the fraction of LDA correlation in a Hartree-Fock/DFT hybrid functional
NBANDS = 16 !number of occupied bands, I may need more bands than that

PREC = High
ISPIN = 1
ALGO = All ; TIME = 0.4
LREAL= .FALSE. !Auto for supercells and false for small cells
ISMEAR = 0 ! 0=Gaussian, -1=Fermi,-4,-5=tetra, 1-5=M-P order
SIGMA = 0.05
ISIF = 4 ! keep volume constant for primitive unit cell

I am pretty sure my mistake is coming from either my AEXX and ALDAC tags. Here I am not quite sure if
1. for 100% HF exchange screened with the TF vector, is VASP automatically using the LDA correlation or one has to enter the ALDAC tag?
2. is it physically acceptable to add a PBE correlation (with PBE potentials of course) to the sX although the TF wave vector was derived from the uniform electron gas theory?

[support_vasp]

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