[Pw_forum] the high symmetry line of bcc phonon dispersion calculated by pw4.1.2

[Wei Zhou]

hello all, recently I calculated the phonon of  bcc sodium using pw4.1.2,
when I plot the phonon dispersion along high symmtry ,I meet a problem;
for bcc structure ,there are four high symmetry points in crystall
coordinations :
*G:(0,0,0)    H**(1/2,-1/2,1/2 )  P:(1/4,1/4,1/4)   N: (0,0,1/2 )*
**and the pwscf give the following bcc basis
 crystal axes: (cart. coord. in units of a_0)
               a(1) = (  0.500000  0.500000  0.500000 )
               a(2) = ( -0.500000  0.500000  0.500000 )
               a(3) = ( -0.500000 -0.500000  0.500000 )
reciprocal axes: (cart. coord. in units 2 pi/a_0)
               b(1) = (  1.000000  0.000000  1.000000 )
               b(2) = ( -1.000000  1.000000  0.000000 )
               b(3) = (  0.000000 -1.000000  1.000000 )
and I turn the high symmetry points into 2 pi/a units using pwscf ,then the
four high symmetry points became :
* G :(0,0,0) ,H* *( 1.00  -1.00,1.00), P(0.00,0.00, 0.50),N(0.00, -0.50,
0.50)*
 I plot the phonon  dispersion along the high symmetry *H-P-G-H-N-P-N-G, *the
results is obivously wrong, which differ the results from others ,I am sure
the phonon calculations does not have problem , the problem is to how to get
the correct the symmetry lines.
 and I also found if I use the following high symmetry points directly ,then
the results is OK
* G :(0,0,0) ,H* *( 0.00  1.00,0.00), P(0.5,0.5, 0.50),N(0.5, 0.5, 0.00)*
then I feel puzzled, would some one give some idea about this?
any help will be appreciated

-- 
ZhouDawei
JiLin Universiyt ,ChangChun ,China
zdw2000 at gmail.com
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