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[Vivek Ranjan <vranjan@uark.edu>]

Dear Abinit users,
        I am trying to do a phonon calculation for a hexagonal system (P3
m 1 #156). I have ddb files at G, K, H, A, L and M q-points. I have merged
all the ddb files and now I want to get the phonon frequencies at 
precisely these points (no points in between).  

(1) I have used the following values :
    brav = 1
    ngqpt = 1 1 1
    nqshft = 1
    q1shft = 0.0  0.0  0.0

when I run the IFC code, it gives me negative values of frequency for the 
two lowest phonons at all q-points.

(2) When I use ngqpt = 2 2 2, all of them become positive.

(3) When I try to get phonon frequencies at q-points between the above 
described high symmetry points, the IFC demands more ddb files to be 
generated at more q-points with ngqpt = 2 2 2.

          Can anyone point out what is the mistake I am committing ? What 
is the correct way to use IFC to get correct phonon frequencies for all 
those high symmetry points and points between them ?

thanks in advance
Vivek