Yambo Community Forum

Dear all,

I used ypp -s b to interpolate band of MoS2 monolayer.
It is known that valence band maximums (VBM) at different valleys (that is, K valley and K' valley) have an opposite spin polarization.
However, the output 'o.spin_factors_DN_interpolated' displays the wrong results. The figure attached show that VBMs at K and K' valleys have the same spin polarization.
The output files and figure plotted by the yambo data are attached.

Best,
Xu

Dear Xu,

the interpolation procedure is just interpolating the values computed on the available k-points.
Since your simulation is with SOC, K and K' should be both computed, e.g. they are not related by symmetry.
Then you can just check the values in your '.spin_factors_UP_built_in' and 'spin_factors_DN_built_in' files.

Add this flag to the input file to generate the latter Can you attach the output files here?
Are you sure you are taking K and K' and not two equivalent K ?

Best,
D.

Dear Davide,

Thanks for your rapid reply!

I saw that the report file in yambo contains a tag showing 'Symmetries: 12 [spatial+T-rev]'. That says the system have time-reversal symmetry. So, I wonder if the interploation process consider the T symmetry.

If the valleys are not related by symmetry, the flag 'force_symmorphic' in QE will be set to False, right? If do that, I think the number of k-points will be large and the simulation is considerably time-consuming. Is there any other method to compute the K and K' valleys simultaneously.

I follow your instruments to uncomment the 'BANDS_built_in' flag, and the outputs are attached.

Are you sure you are taking K and K' and not two equivalent K ?

According to the band circuit set in band.in, the K is -0.333 0.666 0 and K' is 0.333 0.333 0. I think these two point are not equivalent in MoS2 monolayer.