UT theoretical chemistry code forum

Dear All,

In doslanalyze.pl the energy scale is E-Ef to give the d band center with respect to the Fermi level.

Can the band center value change if the energy is taken as only E? In the case of comparing different materials (different Ef), can the trend of band centers be affected and which scale should be used?

Many thanks in advance,
Ibrahim

Yes, it is with respect to the Fermi level. In a periodic calculation, there is no simple absolute energy reference. One strategy is to use the energy of core electrons, which you can include with _pv or _sv potentials. More typical is to use a slab and explicitly calculate the vacuum level as a reference.

Thank you very much Prof. Graeme.

Is it reasonable to use the Fermi energy of one (pristine) material as a reference for the band centers in the case of comparing different (hybrid) materials?

Or should calculate the band center of each material with respect to its Fermi energy?

Best regards,
Ibrahim

This depends a little bit upon what you are interested in. If you want to know about, for example, charge transfer between materials or anything that is based upon the absolute energy levels of the electrons, then you need a common energy reference, such as the vacuum level. If, however, you are wanting to compare something like the catalytic activity of the material then looking at the d-band level with respect to the Fermi level of each material makes sense. I don't think there is any case where you can use the Fermi level of one material as a reference for another.

Thanks Prof. Graeme