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vasp.5.2.2 15Apr09 complex
POSCAR found : 2 types and 96 ions
REAL_OPT: internal ERROR: -32 -32 -32 64
REAL_OPT: internal ERROR: -32 -32 -32 64
REAL_OPT: internal ERROR: -32 -32 -32 64
REAL_OPT: internal ERROR: -32 -32 -32 64
REAL_OPT: internal ERROR: -32 -32 -32 64
Hello,
I'm running ENCUT tests with a set k-point file for uranium dioxide. Two questions:

1) The total energy at 350eV is lower by about 3eV than at higher ENCUTs. I did see the previous post where it suggests to read the accurate.pdf from the VASP tutuorial. But this is not fully addressing the situation.

2) When I go above ENCUT = 600eV, I consistently get the following error:

REAL_OPT: internal ERROR: -32 -32 -32 64
REAL_OPT: internal ERROR: -32 -32 -32 64
REAL_OPT: internal ERROR: -32 -32 -32 64
REAL_OPT: internal ERROR: -32 -32 -32 64
REAL_OPT: internal ERROR: -32 -32 -32 64
REAL_OPT: internal ERROR: -32 -32 -32 64
REAL_OPT: internal ERROR: -32 -32 -32 64
REAL_OPT: internal ERROR: -32 -32 -32 64
REAL_OPT: internal ERROR: -32 -32 -32 64
REAL_OPT: internal ERROR: -32 -32 -32 64
WARNING: PSMAXN for non-local potential too small

I tried changing the O potential to O_h as suggested in a previous post, but to no avail.

Any ideas?
Thank you,
torey

the reason most probably is that you join 2 potentials with very different cutoff, with the POTCAR with the SMALL cutoff (U) being the first in the list. This potentials is used to determine PSMAXN.
please
1) switch the 2 atoms in POSCAR and POTCAR (ie give the atoms such that those with the hardest potentials are first
2) OR use O_s (soft O, low cutoff)