Dear vasp users:
I have encountered a rather unusual behavior when using the vasp code. When running fixed volume runs with the paw-pbe pseudopotential, I have found that in the expanded pressure region as the volume increases, the pressure increases as well! (In the compressed pressure region, the pressure-volume relationship was correct -- as volume increased, pressure decreased. This non-physical behavior shows up only in the expanded pressure region) Clearly, this isn't physical, and I am wondering if there is a bug in the paw-pbe pseudopotentials at expanded pressures?
I have searched the forum, but have not seen any other reports of this behavior. We are using vasp.4.6.28 on Opteron 64-bit dual processor machines, compiled with the Intel Fortran 9.0 code.
I am using these pseudopotentials:
PAW_PBE O_s 07Sep2000, PAW_PBE Fe_pv 06Sep2000 and PAW_PBE Si 05Jan2001
Any advice would be greatly appreciated. Thanks!
Amy
paw-pbe at expanded pressures. As volume inceases, pressure increases as well!
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paw-pbe at expanded pressures. As volume inceases, pressure increases as well!
Last edited by akberta on Tue Oct 04, 2005 8:34 pm, edited 1 time in total.
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paw-pbe at expanded pressures. As volume inceases, pressure increases as well!
first of all, please carefully check if your basis set size is converged:
all data calculated on the basis of the stress tensors require very
high precision (set ENCUT to at least 1.3 * max(ENMAX) in INCAR)
as a hint for insufficient basis set size: the total drift in the forces should be smaller than the forces acting on the ions themselves (OUTCAR).
all data calculated on the basis of the stress tensors require very
high precision (set ENCUT to at least 1.3 * max(ENMAX) in INCAR)
as a hint for insufficient basis set size: the total drift in the forces should be smaller than the forces acting on the ions themselves (OUTCAR).
Last edited by admin on Wed Nov 16, 2005 1:33 pm, edited 1 time in total.