[Wien] PHONON calculation

[puday at iitk.ac.in]

Dear SUDDHASATTWA
I am sending this mail to you only.
I am doing PHONON calculation using WIEN2K.I am making super cell like
2x2x2 and making *.D45 file using phonon.Now while doing init_phono_lapw I
put nn=2. It ask for the new structure file created.I don't accept the new
structure file.Next comes the space group option as given bellow

-----> DO YOU WANT TO USE THE NEW case_1.struct_nn file (y/n)
n

warning: !!! Struct file is not consistent with space group found.
Number and name of space group: 99 (P 4 m m)
warning: !!! Number of inequivalent atoms has changed.
           !!! Old value= 16     New value= 8
warning: !!! Struct file is not consistent with space group found.
 ----->  check in  case_1.outputsgroup  for proper symmetry, compare
         with your struct file and later with  case_1.outputs
         sgroup has also produced a new struct file based on your old one.
         If you see warnings above, consider to use the newly generated
         struct file, which you can view (edit) now.
 ----->  continue with symmetry or edit case_1.struct_sgroup ? (c/e)

If I continue with this then I see the space group have changed for the
super cell than the original structure

Is it right way to do that?


In fact I have done phonon calculation for other 3-4 examples but all of
them giving negative force and negative dispersion.


Have you done PHONON calculation successfully for any structure using WIEN2K?
Please help me.

Regards,
Uday Bhanu Paramanik
Dept.of Physics
IIT Kanpur


> Do not accept the new structure file.
>
> It is also mentioned in the UG that
>
> "...sgroup might change the unit cell and then the collection of forces
> into
> the original supercell is not possible"
>
>
>
>
>
>
>
>   _____
>
> From: wien-bounces at zeus.theochem.tuwien.ac.at
> [mailto:wien-bounces at zeus.theochem.tuwien.ac.at] On Behalf Of
> puday at iitk.ac.in
> Sent: Tuesday, January 11, 2011 12:19 PM
> To: Wien at zeus.theochem.tuwien.ac.at
> Subject: [Wien] PHONON calculation
>
>
>
> Dear Prof Blaha and WIEN user,
> I am doing PHONON calculation of "AlNi" as given example in the manual.I
> am making the supercell 2x2x2(16 atoms) of this cubic symmetry using
> phonon and I get a file *.d45 and this file I am using the input structure
> file in WIEN2K.
> Now I am running init_phonon_lapw
> I am putting nn=2
> and this warning is coming.....
>
>     ATOM 16  Ni         ATOM  8  Al
>  RMT( 16)=2.28000 AND RMT(  8)=2.02000
>  SUMS TO 4.30000  LT.  NN-DIST= 4.70099
>  WARNING: Mult not equal. PLEASE CHECK outputnn-file
>  WARNING: Mult not equal. PLEASE CHECK outputnn-file
>  WARNING: ityp not equal. PLEASE CHECK outputnn-file
>  WARNING: ityp not equal. PLEASE CHECK outputnn-file
>  WARNING: Mult not equal. PLEASE CHECK outputnn-file
>  WARNING: ityp not equal. PLEASE CHECK outputnn-file
>  WARNING: Mult not equal. PLEASE CHECK outputnn-file
>  WARNING: ityp not equal. PLEASE CHECK outputnn-file
>  WARNING: Mult not equal. PLEASE CHECK outputnn-file
>  WARNING: ityp not equal. PLEASE CHECK outputnn-file
>  WARNING: Mult not equal. PLEASE CHECK outputnn-file
>  WARNING: ityp not equal. PLEASE CHECK outputnn-file
>  WARNING: Mult not equal. PLEASE CHECK outputnn-file
>  WARNING: ityp not equal. PLEASE CHECK outputnn-file
>  WARNING: Mult not equal. PLEASE CHECK outputnn-file
>  WARNING: ityp not equal. PLEASE CHECK outputnn-file
>  WARNING: Mult not equal. PLEASE CHECK outputnn-file
>  WARNING: ityp not equal. PLEASE CHECK outputnn-file
>  WARNING: Mult not equal. PLEASE CHECK outputnn-file
>  WARNING: ityp not equal. PLEASE CHECK outputnn-file
>  WARNING: Mult not equal. PLEASE CHECK outputnn-file
>  WARNING: ityp not equal. PLEASE CHECK outputnn-file
>  WARNING: Mult not equal. PLEASE CHECK outputnn-file
>  WARNING: ityp not equal. PLEASE CHECK outputnn-file
> FORTRAN STOP NN created a new CASE.STRUCT_NN FILE
> 0.021u 0.001s 0:01.22 1.6%      0+0k 0+0io 0pf+0w
> -----> check in  case_1.outputnn  for overlapping spheres,
>        coordination and nearest neighbor distances
> -----> DO YOU WANT TO USE THE NEW case_1.struct_nn file (y/n)
>
>
> If I accept this new structure file and new space group 99 (P 4 m m) then
> the program is running but while calculating Hellmann-Feynman forces and
> dispersion curve I am not getting same as given in the example. Forces and
> Dispersion curve going into negative!!
>
>
> One thing is written in the WIEN2K user manual I am putting that line
> here.
>
> Please use mainly nn to reduce equivalent atoms. sgroup might change the
> unitcell and than the collection of forces into the original supercell is
> not possible (or quite difficult).
>
> I don't understand these lines.
> Any help will be highly appreciated.
>
>
> Regards,
> Uday
> Dept.of Physics
> Indian Institute of Technology, Kanpur
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