[Pw_forum] phonon at Gamma

[Ezad Shojaee]

hi
calculating phonons at gamma for my case, i have some frequencies minus and 
far from experimental data. there is no doubt in the structure and these are 
my input parameters

ecutwfc=200
ecutrho=1600
K_points {automatic}
12  12  6   0 0 0

and the calculation is in the GGA approximation
what have i missed?
thanx for any help

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