NBMOD: Difference between revisions

Latest revision as of 14:50, 22 February 2024

NBMOD = -3 | -2 | -1 | 0 | [positive integer]

Default: NBMOD	= n	if IBAND is set and contains n values
	= -2	if EINT is set and IBAND is not set
	= -1	if neither EINT nor IBAND are set

Description: NBMOD controls how bands are selected when computing partial charge densities.

NBMOD is used with other tags to define mode of band selection for partial charge densities in PARCHG or CHGCAR files. There are several ways to set this tag.

NBMOD = n: Use n bands

If a positive integer is passed, NBMOD represents the number of values in the array IBAND. If IBAND is specified, NBMOD is set automatically to the number of values passed in IBAND.

Tip: There is no good reason to set NBMOD to a positive integer since it will be overwritten regardless if IBAND is set or not. Use the IBAND tag alone to enter this mode.

NBMOD = 0: Use all bands

All bands, even unoccupied ones, are contributing to calculating the partial charge density. E.g. the resulting partial charge density in the PARCHG file will sum up to twice the value of the number of total bands NBANDS.

NBMOD = -1: Use all occupied bands

This mode writes the charge density of all occupied states to the CHGCAR file, and no PARCHG file is produced. In contrast to producing a CHGCAR file from the WAVECAR input without the partial charges methodology (e.g. by setting LPARD = .FALSE., ALGO = None, and NELM = 1), the augmentation occupancies is not included in the produced CHGCAR file for NBMOD = -1. THowever, the fine FFT grid's valence charge density is equivalent.

NBMOD = -2: Use an absolute energy interval to select contributing bands

The partial charge density is calculated for electrons in the energy interval specified by EINT.

NBMOD = -3: Use an energy interval to select contributing bands and add the Fermi energy $\epsilon _{f}$ to the passed values

The partial charge density is calculated for electrons in the energy interval specified by EINT. In this mode, the values in EINT are interpreted as relative to the Fermi energy

\epsilon _{f}

. E.g. if EINT = -0.1 0.5 and

\epsilon _{f}

= 2.43, the chosen energy interval will range from 2.33 to 2.93 eV.

@@ Line 2: / Line 2: @@
 {{DEF|NBMOD|n| if {{TAG|IBAND}} is set and contains n values |-2| if {{TAG|EINT}} is set and {{TAG|IBAND}} is not set |-1| if neither {{TAG|EINT}} nor {{TAG|IBAND}} are set}}
-Description: {{TAG|NBMOD}} controls how bands are selected when computing partial charge densities.
+Description: {{TAG|NBMOD}} controls how bands are selected when computing [[Band-decomposed charge densities|partial charge densities]].
 ----
-{{TAG|NBMOD}} is used in conjunction with other tags to define the mode of band selection for partial charge densities saved to {{FILE|PARCHG}} or {{FILE|CHGCAR}} files. There are several possibilities for how this tag can be set, but the use of a positive value for {{TAG|NBMOD}} in the {{FILE|INCAR}} is discouraged.
+{{TAG|NBMOD}} is used with other tags to define mode of band selection for partial charge densities in {{FILE|PARCHG}} or {{FILE|CHGCAR}} files. There are several ways to set this tag.
 * {{TAG|NBMOD}} = n: Use n bands
 :If a positive integer is passed, {{TAG|NBMOD}} represents the number of values in the array {{TAG|IBAND}}. If {{TAG|IBAND}} is specified, {{TAG|NBMOD}} is set automatically to the number of values passed in {{TAG|IBAND}}.
@@ Line 16: / Line 15: @@
 * {{TAG|NBMOD}} = -1: Use all occupied bands
-: This mode writes the charge density of all occupied states to the {{FILE|CHGCAR}} file, and no {{FILE|PARCHG}} file is produced. In contrast to producing a {{FILE|CHGCAR}} file from the {{FILE|WAVECAR}} input without the partial charges methodology (e.g. by setting {{TAG|LPARD}} = .FALSE., {{TAG|ALGO}} = None, and {{TAG|NELM}} = 1), the [[Projector-augmented-wave_formalism#The_compensation_or_augmentation_density|augmentation density]] is not included in the produced {{FILE|CHGCAR}} file for {{TAG|NBMOD}} = -1.
+: This mode writes the charge density of all occupied states to the {{FILE|CHGCAR}} file, and no {{FILE|PARCHG}} file is produced. In contrast to producing a {{FILE|CHGCAR}} file from the {{FILE|WAVECAR}} input without the partial charges methodology (e.g. by setting {{TAG|LPARD}} = .FALSE., {{TAG|ALGO}} = None, and {{TAG|NELM}} = 1), the [[Projector-augmented-wave_formalism#The_compensation_or_augmentation_density|augmentation occupancies]] is not included in the produced {{FILE|CHGCAR}} file for {{TAG|NBMOD}} = -1. THowever, the fine FFT grid's valence charge density is equivalent.
 * {{TAG|NBMOD}} = -2: Use an absolute energy interval to select contributing bands
 : The partial charge density is calculated for electrons in the energy interval specified by {{TAG|EINT}}.
-* {{TAG|NBMOD}} = -3: Use an energy interval with respect to the Fermi energy to select contributing bands
+* {{TAG|NBMOD}} = -3: Use an energy interval to select contributing bands and add the Fermi energy <math>\epsilon_f</math> to the passed values
 : The partial charge density is calculated for electrons in the energy interval specified by {{TAG|EINT}}. In this mode, the values in {{TAG|EINT}} are interpreted as relative to the Fermi energy <math>\epsilon_f</math>. E.g. if {{TAG|EINT}} = -0.1 0.5 and <math>\epsilon_f</math> = 2.43, the chosen energy interval will range from 2.33 to 2.93 eV.
@@ Line 32: / Line 31: @@
 {{TAG|LSEPK}},
 {{FILE|PARCHG}},
-{{TAG|Band decomposed charge densities}}
+[[Band-decomposed charge densities]]
 {{sc|NBMOD|Examples|Examples that use this tag}}
 ----
-[[Category:INCAR tag]][[Category:Electronic minimization]][[Category:Charge density]]
+[[Category:INCAR tag]][[Category:Charge density]]

Latest revision as of 14:50, 22 February 2024

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