[Wien] Effective mass

[Peter Blaha]

mstar calculates the masses for any k-point in case.klist and "all" bands.

If you want "effective" masses for CB and VB, you have to average 
yourself or maybe for your purpose of "temperature-dependent masses at 
VBM/CBM" the boltztrap program may be an alternative.

(PS: the band ranges in case.scf2 give you the band indices)

Am 09.04.2026 um 11:10 schrieb Laurence Marks:
> I am referring to the standard definition of effective masses for the CB 
> & VB, e.g. https://en.wikipedia.org/wiki/Effective_mass_(solid- 
> state_physics) <https://en.wikipedia.org/wiki/Effective_mass_(solid- 
> state_physics)>. This is the tensor at the VB edge for holes and the CB 
> edge for electrons.
> 
>  From what I can see one has to take the mstar output, do a seperate 
> spaghetti type analysis to find the k-points for the LUMO/HOMO, then 
> extract those by hand from the mstar data dump with, perhaps, some 
> Fermi-Dirac averaging for STP, TEMPS Mermin functional. (There might be 
> a cleaner method than spaghetti to find the HOMO/LUMO k-points.)
> 
> ___
> Emeritus Professor Laurence Marks (Laurie)
> Department of Materials Science and Engineering, Northwestern University
> www.numis.northwestern.edu <http://www.numis.northwestern.edu>
> "Research is to see what everybody else has seen, and to think what 
> nobody else has thought" Albert Szent-Györgyi
> 
> On Thu, Apr 9, 2026, 03:47 Rubel, Oleg <rubelo at mcmaster.ca 
> <mailto:rubelo at mcmaster.ca>> wrote:
> 
>     Are you referring to the transport-equivalent effective mass for
>     degenerate bands, perhaps in the sense of Sec. IIIB of this paper on
>     the ABINIT implementation: https://arxiv.org/abs/1708.05890
>     <https://arxiv.org/abs/1708.05890>
>     mstar uses degenerate perturbation theory and can obtain masses
>     associated with, for example, heavy-hole and light-hole branches. It
>     also reports a conductivity-related mass via Eq. (9) in our paper:
>     https://rubel75.github.io/publications/2021/Rubel-CPC_261_2021.pdf
>     <https://rubel75.github.io/publications/2021/Rubel-CPC_261_2021.pdf>
>     However, these quantities are still associated with the resolved
>     degenerate manifold, so I am not sure we went as far as the ABINIT
>     implementation in defining a transport-equivalent effective mass for
>     the full degenerate extremum.
> 
>     Oleg
>      > -----Original Message-----
>      > From: Wien <wien-bounces at zeus.theochem.tuwien.ac.at <mailto:wien-
>     bounces at zeus.theochem.tuwien.ac.at>> On Behalf Of
>      > Laurence Marks
>      > Sent: Wednesday, April 8, 2026 6:11 PM
>      > To: A Mailing list for WIEN2k users
>     <wien at zeus.theochem.tuwien.ac.at
>     <mailto:wien at zeus.theochem.tuwien.ac.at>>
>      > Subject: Re: [Wien] Effective mass
>      >
>      >   Caution: External email.
>      > ..not the decomposition by band and kpoint...
>      >
>      > ---
>      > Emeritus Professor Laurence Marks (Laurie)
>     www.numis.northwestern.edu <http://www.numis.northwestern.edu>
>      > <http://www.numis.northwestern.edu <http://
>     www.numis.northwestern.edu>>
>      > https://scholar.google.com/citations?user=zmHhI9gAAAAJ&hl=en
>     <https://scholar.google.com/citations?user=zmHhI9gAAAAJ&hl=en>
>      > "Research is to see what everybody else has seen, and to think
>     what nobody
>      > else has thought" Albert Szent-Györgyi
>      >
>      > On Wed, Apr 8, 2026, 17:05 Laurence Marks
>     <laurence.marks at gmail.com <mailto:laurence.marks at gmail.com>
>      > <mailto:laurence.marks at gmail.com
>     <mailto:laurence.marks at gmail.com>> > wrote:
>      >
>      >
>      >       It gives them for each band. The conventional definition of
>     electron &
>      > hole effective masses are at the VB and CB edges, which is what I
>     want, not the
>      > decomposition by band.
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> 
> 
> 
> 
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-- 
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Peter Blaha,  Inst. f. Materials Chemistry, TU Vienna, A-1060 Vienna
Email: peter.blaha at tuwien.ac.at
WWW:   http://www.imc.tuwien.ac.at      WIEN2k: http://www.wien2k.at
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