The ABINIT Users Mailing List ( CLOSED )

[Thanusit Burinprakhon <thanusit@kku.ac.th>]

Dear Abinit users

I’ve followed the tutorial on non-linear properties of AlAs, tnlo5. There
reports in the anaddb output file a block of the First-order change in the
electronic dielectric susceptibility tensor induced by an atomic displacement
(dchi/dtau). Are these dchi/dtau corresponding to the pure TO phonons or LO
phonon? 

Having studied the work of M. Veithen, X. Gonze, and Ph. Ghosez in Phy.Rev.B
71,125107(2005), I understand that dchi/dtau are computed slightly differently
for the pure TO and for the LO phonons, at q=0. Where in the latter case, the
effect of macroscopic electric field generated by the lattice polar vibration
is taken into account. So, should we expect two different sets of dchi/dtau
from which Raman susceptibility for the TO and LO phonon are calculated?  If
this is the case, is it possible to have both sets of dchi/dtau reported in 
the
anaddb output file?

Kind Regards,
Thanusit Burinprakhon

List of the dchi/dtau from the tnlo5.out
------------------------------------------------
First-order change in the electronic dielectric 
  susceptibility tensor (Bohr^-1)
  induced by an atomic displacement
  (after imposing the sum over all atoms to vanish)
   atom  displacement
    1          1        0.000000000        0.000000000        0.000000000
                        0.000000000        0.000000000       -0.094488223
                        0.000000000       -0.094488223        0.000000000
    1          2        0.000000000        0.000000000       -0.094488223
                        0.000000000        0.000000000        0.000000000
                       -0.094488223        0.000000000        0.000000000
    1          3        0.000000000       -0.094488223        0.000000000
                       -0.094488223        0.000000000        0.000000000
                        0.000000000        0.000000000        0.000000000

    2          1        0.000000000        0.000000000        0.000000000
                        0.000000000        0.000000000        0.094488223
                        0.000000000        0.094488223        0.000000000
    2          2        0.000000000        0.000000000        0.094488223
                        0.000000000        0.000000000        0.000000000
                        0.094488223        0.000000000        0.000000000
    2          3        0.000000000        0.094488223        0.000000000
                        0.094488223        0.000000000        0.000000000
                        0.000000000        0.000000000        0.000000000