CUTOFF MU: Difference between revisions

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{{TAGDEF|CUTOFF_MU| [real]}}
{{DISPLAYTITLE:CUTOFF_MU}}
{{TAGDEF|CUTOFF_MU| [real] ( [real] )}}
{{DEF|CUTOFF_MU| 0.8 * Fermi level of a system with {{TAG|NUM_WANN}} orbitals occupied|}}
{{DEF|CUTOFF_MU| 0.8 * Fermi level of a system with {{TAG|NUM_WANN}} orbitals occupied|}}


Description: {{TAG|CUTOFF_MU}} Specifies a cutoff energy <math>\mu</math> in units of eV for the cutoff function specified by {{TAG|CUTOFF_MU}}.
Description: {{TAG|CUTOFF_MU}} specifies the energy cutoff <math>\mu</math> in eV for the function specified by {{TAG|CUTOFF_MU}}.
 
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Corresponds to the cutoff energy of the cutoff function to be used to obtain Wannier functions with the
The value <math>\mu</math> of {{TAG|CUTOFF_MU}} corresponds to the energy cutoff of the cutoff function used to obtain Wannier functions with the
[[Wannier_functions#One-shot_single_value_decomposition (SVD)| one-shot method]].
[[Wannier_functions#One-shot_single_value_decomposition (SVD)| one-shot method]].
The meaning depends on the {{TAG|CUTOFF_TYPE}} tag.
The meaning of <math>\mu</math> depends on the {{TAG|CUTOFF_TYPE}} tag.
 
For spin-polarized calculations ({{TAGO|ISPIN|2}}), two values can be specified for {{TAG|CUTOFF_MU}}, one for each spin channel.
If only a single value is specified, it will be used for both spin channels.


The default value is computed by first determining the Fermi level  
The default value is computed by first determining the Fermi level  
of the system if it had {{TAG|NUM_WANN}} orbitals occupied and multiplying by 0.8. This gives reasonable freedom to determine the unitary matrix <math>U_{mn\mathbf{k}}</math> from Bloch states to Wannier functions.
of the system if it had {{TAG|NUM_WANN}} orbitals occupied and multiplying by 0.8. This gives reasonable freedom to determine the unitary transformation <math>U_{mn\mathbf{k}}</math> from Bloch states to Wannier functions.
 
{{NB|tip|Careful tuning of this parameter is required to obtain a good Wannierization.}}
Careful tuning of this parameter is required to obtain a good Wannierization.


== Related tags and articles==
== Related tags and articles==
{{TAG|CUTOFF_TYPE}},
{{TAG|CUTOFF_TYPE}},
{{TAG|CUTOFF_MU}},
{{TAG|CUTOFF_SIGMA}},
{{TAG|CUTOFF_SIGMA}},
{{TAG|LSCDM}},
{{TAG|LSCDM}},

Latest revision as of 14:00, 27 June 2024

CUTOFF_MU = [real] ( [real] ) 

Default: CUTOFF_MU = 0.8 * Fermi level of a system with NUM_WANN orbitals occupied

Description: CUTOFF_MU specifies the energy cutoff in eV for the function specified by CUTOFF_MU.


The value of CUTOFF_MU corresponds to the energy cutoff of the cutoff function used to obtain Wannier functions with the one-shot method. The meaning of depends on the CUTOFF_TYPE tag.

For spin-polarized calculations (ISPIN = 2), two values can be specified for CUTOFF_MU, one for each spin channel. If only a single value is specified, it will be used for both spin channels.

The default value is computed by first determining the Fermi level of the system if it had NUM_WANN orbitals occupied and multiplying by 0.8. This gives reasonable freedom to determine the unitary transformation from Bloch states to Wannier functions.

Tip: Careful tuning of this parameter is required to obtain a good Wannierization.

Related tags and articles

CUTOFF_TYPE, CUTOFF_SIGMA, LSCDM, LOCPROJ

Examples that use this tag