effective masses for hole

[shubhamsinghphy]

Dear team,

I would like to know why effective masses for hole using sumo-bandstats is giving overestimated value.

I was checking for MoS2

Indirect band gap: 1.661 eV
Direct band gap: 1.676 eV
k-point: [0.33, 0.33, 0.00]
k-point indices: 199, 200
Band indices: 13, 14

Valence band maximum:
Energy: -2.083 eV
k-point: [0.00, 0.00, 0.00]
k-point location: GAMMA
k-point indices: 0, 299
Band indices: 13

Conduction band minimum:
Energy: -0.422 eV
k-point: [0.33, 0.33, 0.00]
k-point location: K
k-point indices: 199, 200
Band indices: 14

Using parabolic fitting of the band edges

Hole effective masses:
m_h: -3.070 | band 13 | [0.00, 0.00, 0.00] (GAMMA) -> [0.50, 0.00, 0.00] (M)
m_h: -3.005 | band 13 | [-0.00, -0.00, 0.00] (GAMMA) -> [0.33, 0.33, 0.00] (K)

Electron effective masses:
m_e: 0.447 | band 14 | [0.33, 0.33, 0.00] (K) -> [0.50, 0.00, 0.00] (M)
m_e: 0.440 | band 14 | [0.33, 0.33, 0.00] (K) -> [-0.00, -0.00, 0.00] (GAMMA)

Could you please have a look? I have checked the electronic and lattice parameter and it is matching with reported value.

[utf]

Can you share the band structure?

[shubhamsinghphy]

[utf]

Looking at the band structure, the VBM is at Gamma and the band dispersion from Gamma -> M and Gamma -> K are very flat. For that reason, I don't think sumo is giving the wrong value. The effective masses from K -> Gamma and K -> M look reasonably smaller, but this is not where the VBM is, and so sumo does not report those values.

[shubhamsinghphy]

Actually here band gap is giving indirect (I don't know why). the reported value is direct band gap and hole effective mass is bellow 1. I need to check my calculations in details. Thanks for the response.

[ajjackson]

It does look technically indirect to me: the VBM is at Gamma and the CBM is at K. But the direct gap at K is clearly a very similar energy difference and worth characterising as well.