[Pw_forum] (no subject)

[Raghani Pushpa]

Dear users,
I am calculating the phonon spectrum for a bulk system. For that I 
calculate the dynamical matrices at q points in IBZ and then
calculate the force constants in real space. I have the force 
constants for 6x6x6 and 12x12x12 mesh. Then I use the matdyn.f
program to calculate the phonon spectrum. With this program for 6x6x6 mesh 
the phonon spectrum is qualitatively correct but when I use the 12x12x12 
mesh, frequencies at many intermediate pts are incorrect. Does anybody 
have any idea as to why does it happen? With a larger q point mesh, the 
phonon spectrum should improve, isn't it?  


Pushpa
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