The ABINIT Users Mailing List ( CLOSED )

["Aldo Humberto Romero" <aromero@qro.cinvestav.mx>]

Dear Gao

maybe I am confussed about your question, but the assignments
of the irreducible representation could be done by  looking
at the symmetries of the eigenvectors (look at the
vectors ad you can use the bilbao crystallographic erver
to assign the symmetry)... at least that is
what we did in that paper and in a subsequent paper
jap vol 97 053516 (2005), where we look at the so called
silent modes.

I am not sure this is what you want... but at least I hope
it is related to

regards

-ald.



->
-> Dear Colleague,
->
->
->
-> When I use ABINIT to practise to reproduce the LO-TO splitting for ZnO
-> "Pressure dependence of the lattice dynamics of ZnO: An ab initio
-> approach, published on PHYSICAL REVIEW B 69,094306(2004)", I got into
-> trouble at the assignment of vibrational mode for the LO-TO splitting.
->
->
->
-> I can assign the correct irreducible representation to Phonon frequencies
-> when without LO-TO splitting, e.g.,for ZnO(spacegroup,No.186) there exists
-> the relation 2A1+2B1+2E1+2E2 at the Brillouin-zone center (q=0), i.e.,
->
->
->
-> '  Phonon wavevector (reduced coordinates) :  0.00000  0.00000  0.00000
->  Phonon energies in Hartree :
->    0.000000E+00  0.000000E+00  0.000000E+00  3.799350E-04  3.799358E-04
->    1.143489E-03  1.587916E-03  1.587917E-03  1.737701E-03  1.737703E-03
->    1.747231E-03  2.422538E-03
->  Phonon frequencies in cm-1    :
-> -  (0.000000E+00  0.000000E+00  0.000000E+00)A1+E1  (8.338610E+01
-> 8.338626E+01)E2
-> -  (2.509668E+02)B1  (3.485072E+02  3.485076E+02)E1  (3.813812E+02
-> 3.813816E+02)E2
-> -  (3.834728E+02)B1  (5.316857E+02)A1'
->
->
-> When approaching GAMMA center along some different direction in
-> Brillouin-zone, the calcultion results indicate that there will have LO-TO
-> splitting for some vibration mode, but I have no idea on how to assign
-> these phonon frequencies to correct vibrational mode. My output file for
-> this part is as follow,
->
->
->
-> '  Phonon at Gamma, with non-analyticity in the
->   direction (cartesian coordinates)  1.00000  0.00000  0.00000
->  Phonon energies in Hartree :
->    0.000000E+00  0.000000E+00  0.000000E+00  3.799350E-04  3.799358E-04
->    1.143489E-03  1.587916E-03  1.737701E-03  1.737703E-03  1.747231E-03
->    2.149073E-03  2.422538E-03
->  Phonon frequencies in cm-1    :
-> -  0.000000E+00  0.000000E+00  0.000000E+00  8.338610E+01  8.338626E+01
-> -  2.509668E+02  3.485072E+02  3.813812E+02  3.813816E+02  3.834728E+02
-> -  4.716670E+02  5.316857E+02
->
->   Phonon at Gamma, with non-analyticity in the
->   direction (cartesian coordinates)  0.00000  0.00000  1.00000
->  Phonon energies in Hartree :
->    0.000000E+00  0.000000E+00  0.000000E+00  3.799350E-04  3.799358E-04
->    1.143489E-03  1.587916E-03  1.587917E-03  1.737701E-03  1.737703E-03
->    2.422538E-03  2.522783E-03
->  Phonon frequencies in cm-1    :
-> -  0.000000E+00  0.000000E+00  0.000000E+00  8.338610E+01  8.338626E+01
-> -  2.509668E+02  3.485072E+02  3.485076E+02  3.813812E+02  3.813816E+02
-> -  5.316857E+02  5.536868E+02
->
->   Phonon at Gamma, with non-analyticity in the
->   direction (cartesian coordinates)  0.00000  1.00000  0.00000
->  Phonon energies in Hartree :
->    0.000000E+00  0.000000E+00  0.000000E+00  3.799350E-04  3.799358E-04
->    1.143489E-03  1.587917E-03  1.737701E-03  1.737703E-03  1.747231E-03
->    2.149072E-03  2.422538E-03
->  Phonon frequencies in cm-1    :
-> -  0.000000E+00  0.000000E+00  0.000000E+00  8.338610E+01  8.338626E+01
-> -  2.509668E+02  3.485076E+02  3.813812E+02  3.813816E+02  3.834728E+02
-> -  4.716668E+02  5.316857E+02'
->
->
->
-> I am quiet confused on whether the assignment of these phonon
-> frequencies(along different directions) are same as q=0 without LO-TO
-> splitting or not. Would you like to help me assign these Phonon
-> frequencies to the correct vibrational modes? Any suggestion will be
-> appreciated.
->
->
->
-> Thank you very much.
->
->
->
-> Best,
->
->
->
-> Tao
->
->
->
-> BTW, my files including log, input and output files are enclosed as
-> attachment.
->
-> _________________________________________________________________
-> Messenger��ȫ�������ģ������޸�ϵͳ©��������Messenger��ȫ��
-> http://im.live.cn/safe/


-- 

Prof. Aldo Humberto Romero
CINVESTAV-Unidad Queretaro
Libramiento Norponiente 2000
CP 76230, Queretaro, QRO, Mexico
tel: 442 211 9909
fax: 442 211 9938

email: aromero@qro.cinvestav.mx
        aldorome@gmail.com
www: qro.cinvestav.mx/~aromero