The ABINIT Users Mailing List ( CLOSED )

[matthieu verstraete <matthieu.jean.verstraete@gmail.com>]

you should read the error messages at the end of the log, check the
tutorial on LO-TO splitting again, and verify that your datasets are
connected properly (in particular I suspect you are missing a getddk
and have incorrect getwfk).

Matthieu

On Thu, Sep 17, 2009 at 8:37 AM, Sanjeev Kumar Gupta
<skgupta.physics@gmail.com> wrote:
> ---------- Forwarded message ----------
> From: Sanjeev Kumar Gupta <skgupta.physics@gmail.com>
> Date: 16 Sep 2009 10:59
> Subject: Re: [abinit-forum] negative phonon frequencies at gamma point
> To: aromero@qro.cinvestav.mx, forum@abinit.org
>
>
> Dear Abinit User,
>
> Thanking you very much for your nice suggestion, which i got from
> ABINIT users/experts.
>
> Now, I have two problem, first one is i did not got LO-TO separation
> (may be it is showing mettalic nature, but this in not case)  ( i do
> not understand, when i put "rfelfd" then the program will terminate),
> secondly my frequencies are ~2Thz order less from experimental data.
>
> I am attaching my input file and log file with this mail.
>
> Thanks in advance...
>
> Regards
> SANJEEV
>
> 2009/9/11 Sanjeev Kumar Gupta <skgupta.physics@gmail.com>
>>
>> Thank you sir for your suggestion.
>> Here, I am attaching output file, and i am also doing as you suggested.
>>
>> kind regards
>> SKG
>> 2009/9/11 Aldo Humberto Romero <aromero@qro.cinvestav.mx>
>>>
>>>
>>> It seems to me that still the systems is not well converged..
>>> 0.25 GPa still is large... usually a good convergence should be
>>> less than 0.01GPa.. but in any case, this is not too bad
>>> and I do not think it is responsible for the problems you are
>>> having.
>>>
>>> Now with respect to the LO-TO splitting, did you check the
>>> splitting on the gamma calculation?.. you should start
>>> from there... no looking directly at the phonon dispersion..
>>>
>>> On the other hand, when you plot the
>>> DOS from anaddb, did you try to see what happen to small Q values?
>>> let say (0.001, 0, 0) ... compare the values you get from the
>>> anaddb calculation at Gamma with the ones you got from your
>>> calculation... you will see the splitting (hopefully)...
>>> could you send the output of the Gamma calculation? probably that
>>> will help.
>>>
>>> regards
>>>
>>> -aldo.
>>>
>>>
>>> -> == DATASET 14
>>> -> ==================================================================
>>> ->
>>> ->
>>> ->
>>> ->  Real(R)+Recip(G) space primitive vectors, cartesian coordinates
>>> -> (Bohr,Bohr^-1):
>>> ->
>>> ->  R(1)=  0.0000000  5.2250000  5.2250000  G(1)= -0.0956938  0.0956938
>>> -> 0.0956938
>>> ->
>>> ->  R(2)=  5.2250000  0.0000000  5.2250000  G(2)=  0.0956938 -0.0956938
>>> -> 0.0956938
>>> ->
>>> ->  R(3)=  5.2250000  5.2250000  0.0000000  G(3)=  0.0956938  0.0956938
>>> -> -0.0956938
>>> ->
>>> ->  Unit cell volume ucvol=  2.8529153E+02 bohr^3
>>> ->
>>> ->  Angles (23,13,12)=  6.00000000E+01  6.00000000E+01  6.00000000E+01
>>> -> degrees
>>> ->
>>> ->
>>> ->
>>> ->   getcut: wavevector=  0.0000  0.0000  0.0000  ngfft=  48  48  48
>>> ->
>>> ->          ecut(hartree)=     50.000   => boxcut(ratio)=   2.04075
>>> ->
>>> ->
>>> ->
>>> ->
>>> ->
>>> -> Cartesian components of stress tensor (hartree/bohr^3)
>>> ->
>>> ->   sigma(1 1)=  8.32143159E-06  sigma(3 2)=  0.00000000E+00
>>> ->
>>> ->   sigma(2 2)=  8.32143159E-06  sigma(3 1)=  0.00000000E+00
>>> ->
>>> ->   sigma(3 3)=  8.32143159E-06  sigma(2 1)=  0.00000000E+00
>>> ->
>>> ->
>>> ->
>>> ->
>>> ->
>>> -> -Cartesian components of stress tensor (GPa)         [Pressure=
>>> -> -2.4482E-01
>>> -> GPa]
>>> ->
>>> -> - sigma(1 1)=  2.44824938E-01  sigma(3 2)=  0.00000000E+00
>>> ->
>>> -> - sigma(2 2)=  2.44824938E-01  sigma(3 1)=  0.00000000E+00
>>> ->
>>> -> - sigma(3 3)=  2.44824938E-01  sigma(2 1)=  0.00000000E+00
>>> ->
>>> ->
>>> ->
>>> ->
>>> ->
>>> ->
>>> ================================================================================
>>> ->
>>> -> == DATASET 15
>>> -> ==================================================================
>>> ->
>>> ->
>>> ->
>>> ->
>>> ->
>>> ->  Real(R)+Recip(G) space primitive vectors, cartesian coordinates
>>> -> (Bohr,Bohr^-1):
>>> ->
>>> ->  R(1)=  0.0000000  5.2500000  5.2500000  G(1)= -0.0952381  0.0952381
>>> -> 0.0952381
>>> ->
>>> ->  R(2)=  5.2500000  0.0000000  5.2500000  G(2)=  0.0952381 -0.0952381
>>> -> 0.0952381
>>> ->
>>> ->  R(3)=  5.2500000  5.2500000  0.0000000  G(3)=  0.0952381  0.0952381
>>> -> -0.0952381
>>> ->
>>> ->  Unit cell volume ucvol=  2.8940625E+02 bohr^3
>>> ->
>>> ->  Angles (23,13,12)=  6.00000000E+01  6.00000000E+01  6.00000000E+01
>>> -> degrees
>>> ->
>>> ->
>>> ->
>>> ->  getcut: wavevector=  0.0000  0.0000  0.0000  ngfft=  48  48  48
>>> ->
>>> ->          ecut(hartree)=     50.000   => boxcut(ratio)=   2.03103
>>> ->
>>> ->
>>> ->
>>> -> One thing more, when we plot the phonon dispersion curve for full BZ 
>>> using
>>> -> anaddb code, then we got positive frequencies at gamma point but in 
>>> phonon
>>> -> dispersion curve, we did not see any LO-TO separation, what will be
>>> -> reason?,
>>> -> One more, our frequencies are less in magnitude around 30 cm-1 less at
>>> -> gamma
>>> -> point as compared to experimental.
>>> ->
>>> -> At gamma, i got around 342 cm-1, but expt. is 365 cm-1 ..
>>> ->
>>> -> Your suggestion is welcomed.
>>> -> kind regards
>>> -> sanjeev
>>> -> Kind
>>> ->
>>> -> 2009/9/11 Anglade Pierre-Matthieu <anglade@gmail.com>
>>> ->
>>> ->> > What is the final stress?
>>> ->> Pressure= -8.5022E-01 GPa.
>>> ->>
>>> ->>
>>> ->> --
>>> ->> Pierre-Matthieu Anglade
>>> ->>
>>> ->
>>> ->
>>> ->
>>> -> --
>>> -> S. K. Gupta
>>> -> PhD Candidate,
>>> -> Dept. of Physics, Bhavnagar University.
>>> -> Bhavnagar, 364 022., Gujarat, India.
>>> ->
>>>
>>>
>>> --
>>>
>>> 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
>>>
>>
>>
>>
>> --
>> S. K. Gupta
>> PhD Candidate,
>> Dept. of Physics, Bhavnagar University.
>> Bhavnagar, 364 022., Gujarat, India.
>>
>>
>>
>
>
>
> --
> S. K. Gupta
> PhD Candidate,
> Dept. of Physics, Bhavnagar University.
> Bhavnagar, 364 022., Gujarat, India.
>
>
>
> --
> S. K. Gupta
> PhD Candidate,
> Dept. of Physics, Bhavnagar University.
> Bhavnagar, 364 022., Gujarat, India.
>



-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Prof. Matthieu Verstraete

Universite de Liège
Institut de Physique, Bat. B5
Allée du 6 aout, 17
B- 4000 Sart Tilman, Liège
Belgium

Phone : +32 4 366 37 50
Fax   : +32 4 366 36 29

Mail : matthieu.jean.verstraete@gmail.com