[Pw_forum] phonon calculation

[Paolo Giannozzi]

On Fri, 2014-05-02 at 14:09 +0530, Saied Md Pratik wrote:

> NH4Br crystal

> asr='zero-dim'

if it is a real crystal, you shouldn't use 'zero-dim'. 
If it is a molecule in a supercell, you may have unstable 
(and physically irrelevant) libration modes

>    celldm(1) = 1.890359168

putting into celldm(1) the a.u. to A conversion factor
is a bad habit in my opinion, and ot doesn't make sense
if you specify your cell vectors in A:

> CELL_PARAMETERS angstrom
>    5.633079685   0.000000000   0.000000000
>    0.000000000   5.633079685   0.000000000
>    0.000000000   0.000000000   3.982678150

P.

-- 
Paolo Giannozzi, Dept. Chemistry&Physics&Environment, 
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222