[Pw_forum] Question about K-points

[Bipul Rakshit]

Dear Pwscf users,
I have a question about phonon calculation.
I am doing phonon of K2S (antifluorite structure), using 10x10x10
k-points mesh. In that calculations i find -ve frequencies.

But then on increasing the mesh 14x14x14 and also the kinetic energy
cutoff from 32 to 38 Ry, now i am getting all the +ve freq.

Can you please tell me the reason or give me some reference, so that
by reading that i can understand the things.

regards
-- 
Bipul Rakshit
Research Fellow,
S N Bose Centre for Basic Sciences,
Salt Lake,
Kolkata 700 098
India