Author Topic: Fermi energy shifting in band structure  (Read 18006 times)

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Offline [email protected]

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Fermi energy shifting in band structure
« on: August 15, 2025, 14:21 »
In quantumatk when bandstructure is plotted the fermi level is shown as 0, when the log file is seen the fermi level is mentioned as something else. My question is the bandstructure plot that is shown, are the cbm , vbm (other bands) are shifted  by fermi level ? I mean CBM (IN LOG FILE ) = Actual CBM - Fermi energy ? and VBM( IN LOG FILE) = Actual VBM - Fermi energy ?


This is important to know as the property I need to calculate requires the cbm and vbm band edges to be present at a particular level.

Offline kslprasanth

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Re: Fermi energy shifting in band structure
« Reply #1 on: August 19, 2025, 06:34 »
In bandstructure, you will find an option "Energy zero" selected at fermi level. It will shift all the bands by the fermi energy value. Suppose Ef = -0.4 eV, VBM is at -0.8 eV and CBM is at -0.2 eV, the fermi level shifts to 0. this means al the bands will be shifted by 0.4 eV upward. New VBM and CBM would be -0.4 eV and 0.2 eV. It is done because, the band energies are calculated relatively.
If you want absolute band energy without fermi level correction, just change energy zero to Absolute energy.