ISMEAR: Difference between revisions
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{{TAGDEF|ISMEAR|-5 {{!}} -4 {{!}} -3 {{!}} -2 {{!}} -1 {{!}} 0 {{!}} [integer]>0 |1}} | {{TAGDEF|ISMEAR|-15 {{!}} -14 {{!}} -5 {{!}} -4 {{!}} -3 {{!}} -2 {{!}} -1 {{!}} 0 {{!}} [integer]>0 |1}} | ||
Description: {{TAG|ISMEAR}} determines how the partial occupancies ''f''<sub>n'''k'''</sub> are set for each orbital. {{TAG|SIGMA}} determines the width of the smearing in eV. | Description: {{TAG|ISMEAR}} determines how the partial occupancies ''f''<sub>n'''k'''</sub> are set for each orbital. {{TAG|SIGMA}} determines the width of the smearing in eV. | ||
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== Tag options == | == Tag options == | ||
*{{ | *{{TAG|ISMEAR|0|op=>}}: method of Methfessel-Paxton order {{TAG|ISMEAR}} with width {{TAG|SIGMA}}. | ||
{{NB|mind|Methfessel-Paxton can yield erroneous results for insulators because the partial occupancies can be unphysical.|:}} | {{NB|mind|Methfessel-Paxton can yield erroneous results for insulators because the partial occupancies can be unphysical.|:}} | ||
*{{ | *{{TAG|ISMEAR|0}}: Gaussian smearing with width {{TAG|SIGMA}}. | ||
*{{ | *{{TAG|ISMEAR|-1}}: Fermi smearing with width {{TAG|SIGMA}}. | ||
*{{ | *{{TAG|ISMEAR|-2}}: Partial occupancies are read in from the {{FILE|WAVECAR}} and kept fixed throughout run. Alternatively, you can also choose occupancies in the {{FILE|INCAR}} file with the tag {{TAG|FERWE}} (and {{TAG|FERDO}} for {{TAG|ISPIN|2}} calculations). | ||
*{{ | *{{TAG|ISMEAR|-3}}: perform a loop over {{TAG|SMEARINGS}} parameters supplied in the {{FILE|INCAR}} file. | ||
*{{ | *{{TAG|ISMEAR|-4}}: Tetrahedron method without smearing. | ||
*{{ | *{{TAG|ISMEAR|-5}}: Tetrahedron method with Blöchl corrections{{cite|bloechl:prb:1994}} without smearing. | ||
*{{TAG|ISMEAR|-14}}: Tetrahedron method with Fermi-Dirac smearing {{TAG|SIGMA}}. | |||
*{{TAG|ISMEAR|-15}}: Tetrahedron method with Blöchl corrections{{cite|bloechl:prb:1994}} with Fermi-Dirac smearing {{TAG|SIGMA}}. | |||
{{NB|mind|Use a [[KPOINTS|Γ-centered '''k'''-mesh]] for the tetrahedron methods.|:}} | {{NB|mind|Use a [[KPOINTS|Γ-centered '''k'''-mesh]] for the tetrahedron methods.|:}} | ||
== Related tags and articles == | == Related tags and articles == | ||
{{TAG|SIGMA}}, | {{TAG|SIGMA}}, | ||
{{TAG|EFERMI}}, | |||
{{TAG|FERWE}}, | {{TAG|FERWE}}, | ||
{{TAG|FERDO}}, | {{TAG|FERDO}}, | ||
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{{sc|ISMEAR|Examples|Examples that use this tag}} | {{sc|ISMEAR|Examples|Examples that use this tag}} | ||
== References == | |||
[[Category:INCAR tag]][[Category:Electronic occupancy]][[Category:Electronic minimization]][[Category:Density of states]] | [[Category:INCAR tag]][[Category:Electronic occupancy]][[Category:Electronic minimization]][[Category:Density of states]] | ||
Latest revision as of 09:27, 7 July 2026
ISMEAR = -15 | -14 | -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.
Please consider how-to guide to choose the optimal smearing technique.
Tag options
Mind: Methfessel-Paxton can yield erroneous results for insulators because the partial occupancies can be unphysical.
ISMEAR = -2: Partial occupancies are read in from the WAVECAR and kept fixed throughout run. Alternatively, you can also choose occupancies in the INCAR file with the tag FERWE (and FERDO forISPIN = 2calculations).
ISMEAR = -4: Tetrahedron method without smearing.
Mind: Use a Γ-centered k-mesh for the tetrahedron methods.
Related tags and articles
SIGMA, EFERMI, FERWE, FERDO, SMEARINGS, Smearing technique, K-point integration