alpha+bet in calculating absolute eigenvalues

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giacomo giorgi
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alpha+bet in calculating absolute eigenvalues

#1 Post by giacomo giorgi » Thu Mar 12, 2009 4:31 am

Dear admin,
I am new with VASP and especially with band calculations so maybe my question will seem stupid. Nevertheless I try.

In the OUTCAR file of my optimized crystal structure there is the value reporting fermi Energy followed by the band occupation. I also find a line:

E-fermi : 2.6924 XC(G=0): -9.4069 alpha+bet : -8.5093
add alpha+bet to get absolut eigen values

Now I create a substitutional defect on my crystal. At the end of the optimization I find

E-fermi : 2.7146 XC(G=0): -9.4585 alpha+bet : -8.3115
add alpha+bet to get absolut eigen values

Does it mean that if I want to compare the 2 E-fermi I have to add the 2 alpha+bet values and then compare them? Or alpha+bet is only related to band eigenvalues?
thanks
Last edited by giacomo giorgi on Thu Mar 12, 2009 4:31 am, edited 1 time in total.

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alpha+bet in calculating absolute eigenvalues

#2 Post by admin » Thu Mar 12, 2009 2:31 pm

the alpha+bet energies refer to the energy zero (and can be taken as reference level therefor) only for free atoms.
Last edited by admin on Thu Mar 12, 2009 2:31 pm, edited 1 time in total.

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