O atom spinpolarized low symmetry
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Task
Performing a spin-polarized low symmetry calculation of a single oxygen atom in a non cubic box to get the right energy minimum.
Input
POSCAR
O atom in a box 1.0 ! universal scaling parameters 7.0 0.0 0.0 ! lattice vector a(1) 0.0 7.5 0.0 ! lattice vector a(2) 0.0 0.0 8.0 ! lattice vector a(3) 1 ! number of atoms cart ! positions in cartesian coordinates 0 0 0
INCAR
SYSTEM = O atom in a box ISMEAR = 0 ! Gaussian smearing SIGMA = 0.01 ISPIN = 2 ! spin polarized calculation
KPOINTS
Gamma-point only 0 Monkhorst Pack 1 1 1 0 0 0
Calculation
- In the GGA most atoms are characterized by a symmetry broken solution. VASP, however, symmetriyes the charge density according to the determined symmetry of the cell. Check the OUTCAR file, to see what symmetry VASP is using.
- To lower the symmetry, simply change the lattice parameters to 7.0, 7.5 and 8.0 in the POSCAR file (see the example file above) and reduce SIGMA to SIGMA=0.01 in the INCAR file.
- By rerunning VASP one finds a much lower energy:
vasp.5.4.1 05Feb16 (build Aug 22 2016 16:46:23) complex ... ... . .. DAV: 15 -0.189071145737E+01 -0.29321E-03 -0.39183E-05 48 0.478E-02 0.995E-03 DAV: 16 -0.189071145737E+01 -0.27775E-03 -0.39294E-05 40 0.290E-02 0.541E-03 DAV: 17 -0.189104076616E+01 -0.51555E-04 -0.34087E-06 48 0.132E-02 1 F= -.18910408E+01 E0= -.18910408E+01 d E =-.309633E-20 mag= 1.9998