17O NMR calculation

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farahnaz.mlk
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17O NMR calculation

#1 Post by farahnaz.mlk » Tue Jul 02, 2019 9:28 am

Hi everybody!

I'm using VASP for calculation of 17O chemical shift in oxides. My problem is that in some cases the chemical shielding of all oxygen anions in the slab (bulk and surface) shifted more than 100 ppm. I repeat the calculations on different machines with different compilers, smaller EDIFFs, higher cutoffs and KPOINTS, different ISMEAR and SIGMA, adsorbed molecule in both sides of the slab, but the problem doesn't solve.
I also consider the EFG in the calculations that the QUAD_EFG value is correct.

these are the flags that I'm using:

EDIFF = 1E-7
ALGO = Normal
PREC = A
LREAL = .FALSE.
IBRION = 2
IVDW = 12
ISMEAR = 0
SIGMA = 0.05

Chemical Shift :
LCHIMAG = .TRUE.
DQ = 0.001
ICHIBARE = 1
LNMR_SYM_RED = .TRUE.
NLSPLINE = .FALSE.
LEFG = .TRUE.
QUAD_EFG = -25.58 0 0

All the best

Farahnaz

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