[Pw_forum] beta tin structure

[bhabya sahoo]

i want the phonon dispersion curve for beta tin structure
so i gave the positions of atoms as primitive tetragonal structure having
coordinates
0 0 0, .5 0 .25 , .5 .5 .5, 0 .5 .75 like 4a whychoff positions (c/a=.546)
so no of atoms is 4 in the unit cell so in phonon there will be 12 branches
but i have seen 6 branches so how can i put my primitive tetragonal
structure having two atoms in unitcell
or in other way how can i give the input for beta tin structure






b d sahoo
reserch scholar
mumbai
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