EDIFF: Difference between revisions
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{{TAGDEF|EDIFF|[real]|<math>10^{-4}</math>}} | {{TAGDEF|EDIFF|[real]|<math>10^{-4}</math>}} | ||
Description: {{TAG|EDIFF}} specifies the global break condition for the electronic SC-loop. | Description: {{TAG|EDIFF}} specifies the global break condition for the electronic SC-loop. The unit of EDIFF is in eV. | ||
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The relaxation of the electronic degrees of freedom will be stopped if the total (free) energy change and the band structure energy change ('change of eigenvalues') between two steps are both smaller than {{TAG|EDIFF}}. For {{TAG|EDIFF}}=0, {{TAG|NELM}} electronic SC-steps will always be performed. | The relaxation of the electronic degrees of freedom will be stopped if the total (free) energy change and the band structure energy change ('change of eigenvalues') between two steps are both smaller than {{TAG|EDIFF}} (in eV). For {{TAG|EDIFF}}=0, {{TAG|NELM}} electronic SC-steps will always be performed. | ||
'''Mind''': In most cases the convergence speed is exponential. | '''Mind''': In most cases the convergence speed is exponential. For high precision calculations we recommend to decrease EDIFF to 1E-6. For phonon calculations even EDIFF = 1E-7 might be expedient. | ||
== Related Tags and Sections == | == Related Tags and Sections == | ||
Revision as of 08:39, 7 June 2021
EDIFF = [real]
Default: EDIFF =
Description: EDIFF specifies the global break condition for the electronic SC-loop. The unit of EDIFF is in eV.
The relaxation of the electronic degrees of freedom will be stopped if the total (free) energy change and the band structure energy change ('change of eigenvalues') between two steps are both smaller than EDIFF (in eV). For EDIFF=0, NELM electronic SC-steps will always be performed.
Mind: In most cases the convergence speed is exponential. For high precision calculations we recommend to decrease EDIFF to 1E-6. For phonon calculations even EDIFF = 1E-7 might be expedient.