DEG THRESHOLD - Revision history

Schmiedmayer at 11:39, 1 June 2026

2026-06-01T11:39:46Z

← Older revision		Revision as of 11:39, 1 June 2026
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			{{DISPLAYTITLE:DEG_THRESHOLD}}
	{{TAGDEF\|DEG_THRESHOLD\|[real]}}		{{TAGDEF\|DEG_THRESHOLD\|[real]}}
	{{DEF\|DEG_THRESHOLD\| $2 \times 10^{-3}$ \| }}		{{DEF\|DEG_THRESHOLD\| $2 \times 10^{-3}$ \| }}

Schmiedmayer: Schmiedmayer moved page Construction:DEG THRESHOLD to DEG THRESHOLD

2026-06-01T11:38:09Z

Schmiedmayer moved page Construction:DEG THRESHOLD to DEG THRESHOLD

← Older revision		Revision as of 11:38, 1 June 2026
(No difference)

Schmiedmayer at 09:31, 21 April 2026

2026-04-21T09:31:30Z

← Older revision		Revision as of 09:31, 21 April 2026
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	== Related tags and articles ==		== Related tags and articles ==
	{{TAG\|LSUBROT}}		{{TAG\|LSUBROT}}, {{TAG\|LEPSILON}}

	[[Category:INCAR tag]][[Category:~~Electronic minimization~~]]		[[Category:INCAR tag]][[Category:Linear response]]

Schmiedmayer at 08:41, 21 April 2026

2026-04-21T08:41:45Z

← Older revision		Revision as of 08:41, 21 April 2026
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	{{TAGDEF\|DEG_THRESHOLD\|[real]}}		{{TAGDEF\|DEG_THRESHOLD\|[real]}}
	{{DEF\|DEG_THRESHOLD\| $2*10^{-3}$ \| }}		{{DEF\|DEG_THRESHOLD\| $2 \times 10^{-3}$ \| }}

	Description: {{TAG\|DEG_THRESHOLD}} specifies whether two eigenvalues should be treated as degenerate during clustering of orbitals in the linear response code. {{TAG\|DEG_THRESHOLD}} is specified in units of eV.		Description: {{TAG\|DEG_THRESHOLD}} specifies whether two eigenvalues should be treated as degenerate during clustering of orbitals in the linear response code. {{TAG\|DEG_THRESHOLD}} is specified in units of eV.
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	{{NB\|tip\|If you experience large drifts in the Born effective charges and adding more k-points does not help, try adjusting this parameter.}}		{{NB\|tip\|If you experience large drifts in the Born effective charges and adding more k-points does not help, try adjusting this parameter. The total drift in the Born effective charges (calculated with <code>{{TAG\|LEPSILON}} = .TRUE.</code>) can be found in the {{FILE\|OUTCAR}} file, in a block with the following form (see the final line):

			POSITION DIRECTION 1 BORN EFFECTIVE CHARGE (rigid.aug. ionic)
			-----------------------------------------------------------------------------------------
			* * * * * * ( * * )
			-----------------------------------------------------------------------------------------
			total drift (improves with k-points): XXX XXX XXX

			This block is printed separately for each Cartesian direction. For example, <code>DIRECTION 1</code> is the $x$ direction.
			}}

	== Related tags and articles ==		== Related tags and articles ==

Kresse at 16:40, 20 April 2026

2026-04-20T16:40:08Z

← Older revision		Revision as of 16:40, 20 April 2026
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	----		----
	This parameter is used to find degenerate clusters of orbitals. It is used within VASP whenever linear-response calculations are performed (either with respect to external fields or with respect to ionic displacements). VASP internally uses an inverse-iteration solver with imaginary shifting to solve the Sternheimer linear-response equation. If the value is too large, non-degenerate eigenvalue pairs may be detected as degenerate pairs. This can lead to very poor convergence or erroneous results, in particular, for systems with low symmetry and flat semi-core bands. Conversely, too small a value might not lead to a proper detection of all degenerate eigenvalues. For insulating systems, this usually does not lead to substantial errors, since the imaginary shift can handle degenerate eigenvalue/eigenvector pairs (so VASP implements two strategies to handle degenerate pairs, combining them yields more robust results).		This parameter is used to find degenerate clusters of orbitals. It is used within VASP whenever linear-response calculations are performed (either with respect to external fields or with respect to ionic displacements). VASP internally uses an inverse-iteration solver with imaginary shifting to solve the Sternheimer linear-response equation. If the value is too large, non-degenerate eigenvalue pairs may be detected as degenerate pairs. This can lead to very poor convergence or erroneous results, in particular, for systems with low symmetry and flat semi-core bands. Conversely, too small a value might not lead to a proper detection of all degenerate eigenvalues. For insulating systems, this usually does not lead to substantial errors, since the imaginary shift can handle degenerate eigenvalue/eigenvector pairs (so VASP implements two strategies to handle degenerate pairs and combining them yields more robust results).

	It is recommended to use small values for systems without symmetry (e.g., around $10^{-5}$). For highly symmetric insulators, results should be largely insensitive to the choice of {{TAG\|DEG_THRESHOLD}}. For metals, degenerate states with partial occupancies must be correctly resolved to obtain highly accurate results (so {{TAG\|DEG_THRESHOLD}} must be set to a value that allows safe detection of degenerate states).		It is recommended to use small values for systems without symmetry (e.g., around $10^{-5}$). For highly symmetric insulators, results should be largely insensitive to the choice of {{TAG\|DEG_THRESHOLD}}. For metals, degenerate states with partial occupancies must be correctly resolved to obtain highly accurate results (so {{TAG\|DEG_THRESHOLD}} must be set to a value that allows safe detection of degenerate states).

Kresse at 16:39, 20 April 2026

2026-04-20T16:39:24Z

← Older revision		Revision as of 16:39, 20 April 2026
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	----		----
	This parameter is used to find degenerate clusters of orbitals. It is used within VASP whenever linear-response calculations are performed (either with respect to external fields or with respect to ionic displacements). VASP internally uses an inverse-iteration solver with imaginary shifting to solve the Sternheimer linear-response equation. If the value is too large, non-degenerate eigenvalue pairs may be detected as degenerate pairs. This can lead to very poor convergence or erroneous results, in particular, for systems with low symmetry. Conversely, too small a value might not lead to a proper detection of all degenerate eigenvalues. For insulating systems, this usually does not lead to substantial errors, since the imaginary shift can handle degenerate eigenvalue/eigenvector pairs (so VASP implements two strategies to handle degenerate pairs, combining them yields more robust results).		This parameter is used to find degenerate clusters of orbitals. It is used within VASP whenever linear-response calculations are performed (either with respect to external fields or with respect to ionic displacements). VASP internally uses an inverse-iteration solver with imaginary shifting to solve the Sternheimer linear-response equation. If the value is too large, non-degenerate eigenvalue pairs may be detected as degenerate pairs. This can lead to very poor convergence or erroneous results, in particular, for systems with low symmetry and flat semi-core bands. Conversely, too small a value might not lead to a proper detection of all degenerate eigenvalues. For insulating systems, this usually does not lead to substantial errors, since the imaginary shift can handle degenerate eigenvalue/eigenvector pairs (so VASP implements two strategies to handle degenerate pairs, combining them yields more robust results).

	It is recommended to use small values for systems without symmetry (e.g., around $10^{-5}$). For highly symmetric insulators, results should be largely insensitive to the choice of {{TAG\|DEG_THRESHOLD}}. For metals, degenerate states with partial occupancies must be correctly resolved to obtain highly accurate results (so {{TAG\|DEG_THRESHOLD}} must be set to a value that allows safe detection of degenerate states).		It is recommended to use small values for systems without symmetry (e.g., around $10^{-5}$). For highly symmetric insulators, results should be largely insensitive to the choice of {{TAG\|DEG_THRESHOLD}}. For metals, degenerate states with partial occupancies must be correctly resolved to obtain highly accurate results (so {{TAG\|DEG_THRESHOLD}} must be set to a value that allows safe detection of degenerate states).

Kresse at 16:36, 20 April 2026

2026-04-20T16:36:27Z

← Older revision		Revision as of 16:36, 20 April 2026
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	----		----
	This parameter is used to find degenerate clusters of orbitals. It is used within VASP whenever linear-response calculations are performed (either with respect to external fields or with respect to ionic displacements). VASP internally uses an inverse-iteration solver with ~~complex~~ shifting to solve the Sternheimer linear-response equation. If the value is too large, non-degenerate eigenvalue pairs may be detected as degenerate pairs. This can lead to very poor convergence or ~~errorneous~~ results, in particular, for systems with low symmetry. Conversely, too small a value might not lead to a proper detection of all degenerate eigenvalues. For insulating systems, this usually does not ~~cause~~ errors, since the imaginary shift can ~~deal with~~ degenerate eigenvalue/eigenvector pairs.		This parameter is used to find degenerate clusters of orbitals. It is used within VASP whenever linear-response calculations are performed (either with respect to external fields or with respect to ionic displacements). VASP internally uses an inverse-iteration solver with imaginary shifting to solve the Sternheimer linear-response equation. If the value is too large, non-degenerate eigenvalue pairs may be detected as degenerate pairs. This can lead to very poor convergence or erroneous results, in particular, for systems with low symmetry. Conversely, too small a value might not lead to a proper detection of all degenerate eigenvalues. For insulating systems, this usually does not lead to substantial errors, since the imaginary shift can handle degenerate eigenvalue/eigenvector pairs (so VASP implements two strategies to handle degenerate pairs, combining them yields more robust results).

	It is recommended to use ~~tiny~~ values for systems ~~that do not possess any~~ symmetry (~~say~~ around $10^{-5}). For highly symmetric insulators, results should be largely insensitive to the choice of {{TAG\|DEG_THRESHOLD}}. For metals, degenerate states with partial occupancies must be correctly resolved to obtain highly accurate results (so {{TAG\|DEG_THRESHOLD}} must be set to a value that allows safe detection of degenerate states).		It is recommended to use small values for systems without symmetry (e.g., around $10^{-5}$). For highly symmetric insulators, results should be largely insensitive to the choice of {{TAG\|DEG_THRESHOLD}}. For metals, degenerate states with partial occupancies must be correctly resolved to obtain highly accurate results (so {{TAG\|DEG_THRESHOLD}} must be set to a value that allows safe detection of degenerate states).

Kresse: More detailed explanation.

2026-04-20T16:33:16Z

More detailed explanation.

← Older revision		Revision as of 16:33, 20 April 2026
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	{{DEF\|DEG_THRESHOLD\| $2*10^{-3}$ \| }}		{{DEF\|DEG_THRESHOLD\| $2*10^{-3}$ \| }}

	Description: {{TAG\|DEG_THRESHOLD}} specifies whether two eigenvalues should be treated as degenerate during ~~wavefunction~~ clustering. {{TAG\|DEG_THRESHOLD}} is specified in units of eV.		Description: {{TAG\|DEG_THRESHOLD}} specifies whether two eigenvalues should be treated as degenerate during clustering of orbitals in the linear response code. {{TAG\|DEG_THRESHOLD}} is specified in units of eV.

	----		----
	This parameter is used to find clusters of ~~wave functions~~ within ~~a given energy range~~. If it is ~~set~~ too ~~high~~, non-degenerate eigenvalue pairs may be detected as degenerate pairs. ~~Then~~, ~~the inverse iteration will attempt to converge them. Ultimately~~, ~~the program will get stuck and converge poorly~~. Conversely, too small a value might not ~~detect~~ all degenerate eigenvalues. ~~The most severe problems are caused by very narrow semicore bands~~.		This parameter is used to find degenerate clusters of orbitals. It is used within VASP whenever linear-response calculations are performed (either with respect to external fields or with respect to ionic displacements). VASP internally uses an inverse-iteration solver with complex shifting to solve the Sternheimer linear-response equation. If the value is too large, non-degenerate eigenvalue pairs may be detected as degenerate pairs. This can lead to very poor convergence or errorneous results, in particular, for systems with low symmetry. Conversely, too small a value might not lead to a proper detection of all degenerate eigenvalues. For insulating systems, this usually does not cause errors, since the imaginary shift can deal with degenerate eigenvalue/eigenvector pairs.

			It is recommended to use tiny values for systems that do not possess any symmetry (say around $10^{-5}). For highly symmetric insulators, results should be largely insensitive to the choice of {{TAG\|DEG_THRESHOLD}}. For metals, degenerate states with partial occupancies must be correctly resolved to obtain highly accurate results (so {{TAG\|DEG_THRESHOLD}} must be set to a value that allows safe detection of degenerate states).


	{{NB\|tip\|If you experience large drifts in the Born effective charges and adding more k-points does not help, try adjusting this parameter.}}		{{NB\|tip\|If you experience large drifts in the Born effective charges and adding more k-points does not help, try adjusting this parameter.}}

Schmiedmayer at 15:52, 20 April 2026

2026-04-20T15:52:35Z

← Older revision		Revision as of 15:52, 20 April 2026
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	{{NB\|tip\|If you experience large drifts in the Born effective charges and adding more k-points does not help, try adjusting this parameter.}}		{{NB\|tip\|If you experience large drifts in the Born effective charges and adding more k-points does not help, try adjusting this parameter.}}

	~~{{NB\|mind\|This tag is only available from VASP.6.6.1}}~~

	== Related tags and articles ==		== Related tags and articles ==

Schmiedmayer at 15:46, 20 April 2026

2026-04-20T15:46:23Z

← Older revision		Revision as of 15:46, 20 April 2026
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	{{TAGDEF\|~~DEGEN_THR~~\|[real]}}		{{TAGDEF\|DEG_THRESHOLD\|[real]}}
	{{DEF\|~~DEGEN_THR~~\| $2*10^{-3}$ \| }}		{{DEF\|DEG_THRESHOLD\| $2*10^{-3}$ \| }}

	Description: {{TAG\|~~DEGEN_THR~~}} specifies whether two eigenvalues should be treated as degenerate during wavefunction clustering. {{TAG\|~~DEGEN_THR~~}} is specified in units of eV.		Description: {{TAG\|DEG_THRESHOLD}} specifies whether two eigenvalues should be treated as degenerate during wavefunction clustering. {{TAG\|DEG_THRESHOLD}} is specified in units of eV.

	----		----