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Hello,

I am doing shearing calculations for Aluminum with 12 layers. The shear is implemented by tilting the lattice vector normal to the layers. For most shears, I can use a kpoint mesh such as 16x16x4. However for a couple of shears I get the following error:

VERY BAD NEWS! internal error in subroutine IBZKPT:
Reciprocal lattice and k-lattice belong to different class of lattices.

The number of times this appears is equal to the number of CPUs that I am running. This is odd since the shears that have no errors have the same symmetry as the ones that do have the errors. I have tried this calculation with ISYM=0 and I still receive this error. So can the error be ignored?
I have also tried odd meshes and the error still appears. A kmesh that works is NxNxN mesh, such as 16x16x16. This however is a much larger mesh than needed. Is there any way to get around this?


INCAR:
SYSTEM = C
restart settings
ISTART = 0
ICHARG = 2
output settings
LCHARG = T
LWAVE = .FALSE.
LORBIT=10
settings for parallel version (ignored in serial run)
NPAR = 1 how many bands in parallel
LPLANE = .TRUE. distribute each wave over processors

Electronic Relaxation 1
ENCUT = 350
PREC = High
EDIFF = 1E-06
IALGO = 48

Ionic Relaxation
IBRION = -1
ISIF = 2
NSW = 0
EDIFFG = -1E-02

Symmetry settings
ISYM = 0
SYMPREC = 0.0001

DOS related values:
ISMEAR = 1 -4-tet -1-fermi 1=Methfessel/Paxton 1.order
SIGMA = 0.1 broadening in eV

I contacted VASP support directly and they said to do the following:

1) Decrease SYMPREC to 1e-8. This will get rid of the errors but not always.

2) Turning off the symmetry, one does not need to be bothered about the message