ISMEAR: Difference between revisions

Latest revision as of 10:34, 27 February 2025

ISMEAR = -15 | -14 | -5 | -4 | -3 | -2 | -1 | 0 | [integer]>0
Default: ISMEAR = 1

Description: ISMEAR determines how the partial occupancies f_nk 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

ISMEAR > 0: method of Methfessel-Paxton order ISMEAR with width SIGMA.

Mind: Methfessel-Paxton can yield erroneous results for insulators because the partial occupancies can be unphysical.

ISMEAR = 0: Gaussian smearing with width SIGMA.

ISMEAR = -1: Fermi smearing with width SIGMA.

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 for ISPIN = 2 calculations).

ISMEAR = -3: perform a loop over SMEARINGS parameters supplied in the INCAR file.

ISMEAR = -4: Tetrahedron method without smearing.

ISMEAR = -5: Tetrahedron method with Blöchl corrections without smearing.

ISMEAR = -14: Tetrahedron method with Fermi-Dirac smearing SIGMA.

ISMEAR = -15: Tetrahedron method with Blöchl corrections with Fermi-Dirac smearing SIGMA.

Mind: Use a Γ-centered k-mesh for the tetrahedron methods.

@@ Line 1: / Line 1: @@
-{{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.
 ----
-*{{TAG|ISMEAR}}=''N'' (''N''>0): method of Methfessel-Paxton order ''N''.
-:'''Mind''': For the Methfessel-Paxton scheme the partial occupancies can be negative.
-*{{TAG|ISMEAR}}=0: Gaussian smearing.
-*{{TAG|ISMEAR}}=&minus;1: Fermi smearing.
-*{{TAG|ISMEAR}}=&minus;2:partial occupancies are read in from the {{FILE|WAVECAR}} or {{FILE|INCAR}} file, and kept fixed throughout run.
-:To set the occupancies specify
-  {{TAG|FERWE}} = f1 f2 f3 ... f({{TAG|NBANDS}})
-:and for spin-polarized calculations, additionally
-  {{TAG|FERDO}} = f1 f2 f3 ... f({{TAG|NBANDS}})
-:in the {{TAG|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 {{FILE|OUTCAR}} file, but in this case they are multiplied by 2, i.e. they are between 0 and 2.
+Please consider how-to guide to choose the optimal [[smearing technique]].
-*{{TAG|ISMEAR}}=&minus;3:
+== Tag options ==
-*{{TAG|ISMEAR}}=&minus;4:
-*{{TAG|ISMEAR}}=&minus;5:
+*{{TAGO|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.|:}}
+*{{TAGO|ISMEAR|0}}: Gaussian smearing with width {{TAG|SIGMA}}.
+*{{TAGO|ISMEAR|-1}}: Fermi smearing with width {{TAG|SIGMA}}.
+*{{TAGO|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 {{TAGO|ISPIN|2}} calculations).
+*{{TAGO|ISMEAR|-3}}: perform a loop over {{TAG|SMEARINGS}} parameters supplied in the {{FILE|INCAR}} file.
+*{{TAGO|ISMEAR|-4}}: Tetrahedron method without smearing.
+*{{TAGO|ISMEAR|-5}}: Tetrahedron method with Blöchl corrections without smearing.
+*{{TAGO|ISMEAR|-14}}: Tetrahedron method with Fermi-Dirac smearing {{TAG|SIGMA}}.
+*{{TAGO|ISMEAR|-15}}: Tetrahedron method with Blöchl corrections with Fermi-Dirac smearing {{TAG|SIGMA}}.
+{{NB|mind|Use a [[KPOINTS|&Gamma;-centered '''k'''-mesh]] for the tetrahedron methods.|:}}
+== Related tags and articles ==
+{{TAG|SIGMA}},
+{{TAG|EFERMI}},
+{{TAG|FERWE}},
+{{TAG|FERDO}},
+{{TAG|SMEARINGS}},
+[[Smearing technique]],
+[[K-point integration]]
+{{sc|ISMEAR|Examples|Examples that use this tag}}
-== Related Tags and Sections ==
-{{TAG|SIGMA}}
-----
-[[The_VASP_Manual|Contents]]
-[[Category:INCAR]]
+[[Category:INCAR tag]][[Category:Electronic occupancy]][[Category:Electronic minimization]][[Category:Density of states]]