Error in effective mass calculation

[ams_nanolab]

Dear Sir,

I was evaluating the electron and hole effective masses in monolayer MoS2 using the effective mass analyzer. However I am finding some results to be quite surprising. The electron eff mass in the K-->Gamma direction is about 0.540 but the hole effective mass in the same direction is showing 2.002. The same trend is seen in other directions like K--> M etc. This is rather odd as the curvatures of the bottom CB and the top VB at K point seem quite similar from the bandstructure. Also a recent paper [http://prb.aps.org/abstract/PRB/v86/i24/e241401] on effective masses in monolayer MoS2 shows the electron and hole effective masses to be quite close for relaxed monolayer.

In our calculation we are following  the tutorial

http://quantumwise.com/publications/tutorials/mini-tutorials/135

and setting the value of Relative Band Index = 0 for electrons and -1 for holes.

Could you elaborate what is wrong?

[Anders Blom]

There is usually more than one hole band so you can try -2 and -3 as well. Otherwise you have to look at the band structure to see if they are accurate with the given method used for the calculation (Huckel, DFT, whichever).