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Difference between revisions of "ISMEAR"

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:'''Mind''': Partial occupancies are also written to the {{FILE|OUTCAR}} file, but in this case they are multiplied by 2, i.e. they are between 0 and 2.
 
:'''Mind''': Partial occupancies are also written to the {{FILE|OUTCAR}} file, but in this case they are multiplied by 2, i.e. they are between 0 and 2.
  
*{{TAG|ISMEAR}}=−3:
+
*{{TAG|ISMEAR}}=−3: perform a loop over smearing-parameters supplied in the {{FILE|INCAR}} file.
 +
:In this case a tag
 +
  {{TAG|SMEARINGS}}= ismear<sub>1</sub> sigma<sub>1</sub>  ismear<sub>2</sub> sigma<sub>2</sub>  ...
 +
:must be present in the {{FILE|INCAR}} file, supplying different smearing parameters. {{TAG|IBRION}} has to be set to -1 and {{TAG|NSW}} to the number of supplied pairs ismear<sub>i</sub>/sigma<sub>i</sub>. The first loop is done using the tetrahedron method with Blöchl corrections.
 +
 
 
*{{TAG|ISMEAR}}=&minus;4:
 
*{{TAG|ISMEAR}}=&minus;4:
 
*{{TAG|ISMEAR}}=&minus;5:
 
*{{TAG|ISMEAR}}=&minus;5:

Revision as of 16:29, 23 May 2011

ISMEAR = -5 | -4 | -3 | -2 | -1 | 0 | [integer]>0
Default: ISMEAR = 1 

Description: ISMEAR determines how the partial occupancies fnk are set for each orbital. SIGMA determines the width of the smearing in eV.


  • ISMEAR=N (N>0): method of Methfessel-Paxton order N.
Mind: For the Methfessel-Paxton scheme the partial occupancies can be negative.
  • ISMEAR=0: Gaussian smearing.
  • ISMEAR=−1: Fermi smearing.
  • ISMEAR=−2: partial occupancies are read in from the WAVECAR or INCAR file, and kept fixed throughout run.
To set the occupancies specify
 FERWE = f1 f2 f3 ... f(NBANDS)
and for spin-polarized calculations, additionally
 FERDO = f1 f2 f3 ... f(NBANDS)
in the INCAR file. The (partial) occupancies must be specified for all bands and k-points. The band-index runs fastest. The occupancies must be between 0 and 1 (for spin-polarized and non-spin-polarized calculations).
Mind: Partial occupancies are also written to the OUTCAR file, but in this case they are multiplied by 2, i.e. they are between 0 and 2.
  • ISMEAR=−3: perform a loop over smearing-parameters supplied in the INCAR file.
In this case a tag
 SMEARINGS= ismear1 sigma1  ismear2 sigma2  ...
must be present in the INCAR file, supplying different smearing parameters. IBRION has to be set to -1 and NSW to the number of supplied pairs ismeari/sigmai. The first loop is done using the tetrahedron method with Blöchl corrections.

Related Tags and Sections

SIGMA


Contents