My Community

hi everyone
i want to calculate the phonon frequencies at G point.
i have a look at the manual, and i found
Selective dynamics are presently only supported for IBRION=5;
1)so, it means i can not use IBRION=6 (only symmetry inequivalent displacements are considered) and IBRION=7,8( the density functional perturbation theory) when i use selective dynamic?
in fact, i think if i calculate phonon frequency using frozen phonon, all atoms should move one by one. there are no selective, all atoms should be labeled like below. at this point, what should i write in POSCAR?
2) if i want to use density functional perturbation theory to calculate phonon, how i write in POSCAR?( in the density functional perturbation theory, the atoms need not move)
am i right?
0.0000000000000000 0.0000000000000000 0.0045949824006015 T T T
0.0000000000000000 0.0000000000000000 0.2000000000000028 T T T
0.3333333300000021 0.6666666699999979 0.0045629616850880 T T T
0.6666666671999977 0.3333333336000024 0.2000000000000028 T T T
0.0000000000000000 0.0000000000000000 0.3954050287993979 T T T

1) Just take the CONTCAR of your selective optimisation and then it goes. Or put more "F F F" lines for freezing more atoms.
2) I'd guess: Just remove the selective ... line and give it a try.

Hint: you can always figure this out if you go for a water molecule. Then you'll see, what the program is doing without loosing too much CPU time.

Cheers,

alex