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Hello,

I want to calculate the zero point energy for my system in order to compare my theoretical results with experimental data.Firstly, I have performed the geometry optimization calculations for my system. And secondly, I want to calculate the normal mode of my system. I wonder if my INCAR listed below is right, and if this kind of calculation will change my geometry again.

Thanks a lot!

Start parameter for this Run:
ISTART = 0
ICHARG = 2
INIWAV = 1
Electronic Relaxation:
ENCUT = 350
ENAUG = 550
PREC = Accurate
IALGO = 38
NELM = 60
NELMIN = 4
NELMDL = -5
EDIFF = 1E-05
NBANDS = 256
GGA = 91
VOSKOWN = 1
Ionic Relaxation:
EDIFFG = 1E-04
NSW = 1 -------------------> Do NSW=1 and ISIF =2 make me optimize the geometry again?
IBRION = 5
ISIF = 2
NFREE = 2
DOS related values:
SIGMA = 0.1
ISMEAR = 1
Spin polarized:
ISPIN = 2

no, if IBRION=5, no further geometry optimisation step is taken, the displacements of the atoms are just to determine the Hessian matrix.
Please do not forget to set POTIM to a small value which ensures that the displacements are in the harmonic regime

Thank you for your reply! As for a Ni surface with a CH4 above it, what should I set POTIM to? Thanks!