The ABINIT Users Mailing List ( CLOSED )

[Masayoshi Mikami <mmikami@yk.rim.or.jp>]

Have you ever read (peruse) the FAQ and the references therein ?

# Negative frequencies in phonon band structure ?
http://www.abinit.org/wws/arc/forum/2002-09/msg00024.html
# Non-zero phonon frequencies at Gamma point ?
http://www.abinit.org/ABINIT/Infos/FAQ.html#nonzero_phonon

Then you would notice the reason by yourself.

A reply to your previous question (IR-response...) 
can be found in the forum ML archive and solid-state physics textbooks. 
(This could be left as homework ... Help yourself, please.)
I would also like to reiterate the message:
"Read and reread the manual and references ..."

ABINIT will give us such *** self-education *** chances. 
And also, we will also have chances to learn about difference 
between "computing" and "earning good results", thanks to 
the documentations and the forum ML archive. Have fun !


On Mon, 19 Jul 2004 23:37:14 +0800
"Wu Rongqin" <g0203654@nus.edu.sg> wrote:

> Dear all,
> I calculated the phonon at gamma point of SrTiO3, the result seem to
> puzzles me!
> See blow:
> The -97.44653 cm(-1) should be correspondent to the soft norm. but the
> -6.04665 cm(-1) frequency at gamma should be, in my opinion, zero. I
> find increasing k-point and energy cutoff cannot get the zero frequency
> at gamma! The lattice constant has been correctly calculated. Hope for
> your comments
> Rongqin 
> Phonon wavevector (reduced coordinates) :  0.00000  0.00000  0.00000
>  Phonon energies in Hartree :
>   -4.439991E-04 -4.439980E-04 -4.439956E-04 -2.755056E-05 -2.753126E-05
>   -2.752154E-05  1.258732E-04  1.258732E-04  1.258732E-04  8.695282E-04
>    8.695283E-04  8.695296E-04  2.779686E-03  2.779686E-03  2.779686E-03
>  Phonon frequencies in cm-1    :
> - -9.744653E+01 -9.744630E+01 -9.744577E+01 -6.046650E+00 -6.042413E+00
> - -6.040279E+00  2.762598E+01  2.762598E+01  2.762598E+01  1.908394E+02
> -  1.908394E+02  1.908397E+02  6.100705E+02  6.100705E+02  6.100707E+02
>  
>   Phonon at Gamma, with non-analyticity in the
>   direction (cartesian coordinates)  1.00000  0.00000  0.00000
>  Phonon energies in Hartree :
>   -4.439980E-04 -4.439956E-04 -2.814448E-05 -2.753126E-05 -2.752154E-05
>    1.258732E-04  1.258732E-04  1.258732E-04  5.621172E-04  8.695282E-04
>    8.695296E-04  1.540756E-03  2.779686E-03  2.779686E-03  3.648319E-03
>  Phonon frequencies in cm-1    :
> - -9.744630E+01 -9.744577E+01 -6.176999E+00 -6.042413E+00 -6.040279E+00
> -  2.762598E+01  2.762598E+01  2.762598E+01  1.233705E+02  1.908394E+02
> -  1.908397E+02  3.381569E+02  6.100705E+02  6.100705E+02  8.007135E+02
>