[Pw_forum] cann't get the LO-TO spliting using dynmat.x

[sun jason]

Dear all,

follw example06, I calculate the phonon frequency of BN, I can get LO/TO 
spliting using q2r.x + matdyn.x , the result at gamma point is like that:
============================================================
    0.0000    0.0000    0.0001 1055.3982 1055.3982 1294.1370
============================================================

but I cann't get the LO mode when I use dynmat.x, the result is like this:
============================================================
    0.0000    0.0000    0.0001 1055.3982 1055.3982 1055.3982
============================================================
my input file for dynmat.x is like that:
=====================================================
 phonons of cubic BN at 0.0000000,0.0000000,0.0000000
 &input
  amass(1)=10.81100,
  amass(2)=14.00674,
  asr=.true.,
  fildyn='bn.dynG',
  filout='bn.out',
  filmol='bn.molden'
 &end
0.0000000,0.0000000,0.0000000
=====================================================

but someone had told me that both this two methods can be use to get LO/TO 
spliting.
is it right?
why I cann't get the LO mode just use dynmat.x ?

any comment would be appreciated.
 
best regards,

==============================================
Jian Sun 
Physics Dept. of Nanjing University 
National Lab. of Solid State Microstructures 
22 Hankou Road, Gulou District 
Nanjing, Jiangsu Province 
210093 
China
==============================================