Problem in phonon band structure for WSe2 monolayer

[ahsan_javed]

Can you kindly look at and possible reason for four curves instead of six?

[alexey.tal]

Dear ahsan_javed,

One of the possible reasons that you see fewer phonon branches in the dispersion plot is that some of the branches are degenerate.
The questions related to phonopy should be submitted to phonopy developers or experts, as I am not sufficiently knowledgeable about phonopy to provide useful help here.

[ahsan_javed]

I am not using a supercell i.e., POSCAR is of monolayer. Can it be a possible reason for this?

[alexey.tal]

Yes, it could be. You can also perform a phonon dispersion calculation for a supercell using the finite differences method.

[ahsan_javed]

Since i am using SCAN functional, so i probably cannot use this method.

[alexey.tal]

Unlike DFPT the finite difference approach can be used in combination with any exchange-correlation functional.