H2O vibration

• INCAR

SYSTEM = H2O vibration
ISMEAR = 0    # Gaussian smearing
IBRION = 6    # finite differences with symmetry
NFREE = 2     # central differences (default)
POTIM = 0.015 # default as well
EDIFF = 1E-6 
NSW = 1       # ionic steps > 0

• KPOINTS

Gamma-point only
 1        ! one k-point
rec       ! in units of the reciprocal lattice vector
 0 0 0 1  ! 3 coordinates and weight

• POSCAR

H2O _2                                                                          
 0.5291800
  15.0000000   0.0000000   0.0000000
   0.0000000  15.0000000   0.0000000
   0.0000000   0.0000000  15.0000000
    1    2
cart
   0.0000000   0.0000000   0.0000000
   1.1269567  13.5477107   0.0000000
   1.1269567   1.4522893   0.0000000

How many zero frequency modes are observed and why? Are the results sensitive to the step width POTIM Also try to use the linear response code (IBRION=8).

Download

1_8_H2Ovib.tgz

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