O atom spinpolarized low symmetry: Difference between revisions

From VASP Wiki
 
(21 intermediate revisions by 2 users not shown)
Line 1: Line 1:
*{{TAG|INCAR}}
{{Template:At_and_mol - Tutorial}}
SYSTEM = O atom in a box
ISMEAR = 0  ! Gaussian smearing
SIGMA  = 0.01
ISPIN =  2  ! spin polarized calculation


*{{TAG|KPOINTS}}
== Task ==
Gamma-point only
 
  0
Performing a spin-polarized low symmetry calculation of a single oxygen atom in a non cubic box to get the right energy minimum.
Monkhorst Pack
 
  1 1 1
== Input ==
  0 0 0


*{{TAG|POSCAR}}
=== {{FILE|POSCAR}} ===
  O atom in a box
  O atom in a box
   1.0          ! universal scaling parameters
   1.0          ! universal scaling parameters
Line 22: Line 17:
   0 0 0
   0 0 0


== Used INCAR Tags ==
 
{{TAG|ISMEAR}}, {{TAG|ISPIN}}, {{TAG|SIGMA}}, {{TAG|SYSTEM}}
 
=== {{FILE|INCAR}} ===
{{TAGBL|SYSTEM}} = O atom in a box
{{TAGBL|ISMEAR}} = 0  ! Gaussian smearing
{{TAGBL|SIGMA}}  = 0.01
{{TAGBL|ISPIN}} =  2  ! spin polarized calculation
 
=== {{FILE|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, symmetrizes the charge density according to the determined symmetry of the cell. Check the {{TAG|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 {{TAG|POSCAR}} file (see the example file above) and reduce {{TAG|SIGMA}} to {{TAG|SIGMA}}=0.01 in the {{TAG|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
 
== Further things to try ==
 
*How does the energy change when one decreases {{TAG|SIGMA}} to {{TAG|SIGMA}}=0.01 in the {{TAG|INCAR}} file? Why?


== Download ==
== Download ==
[http://www.vasp.at/vasp-workshop/examples/Oatomspinlowsym.tgz Oatomspinlowsym.tgz]
[[Media:Oatomspinlowsym.tgz|Oatomspinlowsym.tgz]]
----
[[VASP_example_calculations|To the list of examples]] or to the [[The_VASP_Manual|main page]]
{{Template:At_and_mol}}


[[Category:Examples]]
[[Category:Examples]]

Latest revision as of 14:16, 14 November 2019

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, symmetrizes 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

Further things to try

  • How does the energy change when one decreases SIGMA to SIGMA=0.01 in the INCAR file? Why?

Download

Oatomspinlowsym.tgz