[gpaw-users] Phonon band structure

[Georg Madsen]

I like phon and with ase it is easy to use. You run it in a three step
procedure.
1 Save a POSCAR file
2 Run phon which will analyze symmetry and make a DISP file which looks
something like
  "   1  0.00294985  0.00000000  0.00000000 " \
 "   3  0.00294985  0.00000000  0.00000000 " \
 "   3  0.00000000  0.00000000  0.00294985 "  \
You then simply run a DFT calc with each displacement frozen in.The only
thing is to parse the DISP. We do this with:
----------------------------------------------------------------------------------------
file1 = open('DISP')
atoms2 = atoms.copy()
pos = atoms.get_scaled_positions()
for line in file1:
        arg = line.split()
        atn,disp = int(arg[1]),[float(arg[2]),float(arg[3]),float(arg[4])]
        pos[atn-1] = pos[atn-1] + disp
        atoms2.set_scaled_positions(pos)
        << run DFT calc >>
----------------------------------------------------------------------------------------
You then just need to write the FORCES file and phon does the rest. We
write the FORCES with
----------------------------------------------------------------------------------------
dfile = open('DISP', 'r')
dlines = dfile.readlines()
dfile.close()
ffile = open('FORCES', 'w')
print >> ffile, len(dlines)

for line in dlines:
    sline = line.split()
    atid = int(sline[1])
    print >> ffile, '%3i % 10.8f % 10.8f % 10.8f'%(atid,
float(sline[2]),float(sline[3]),float(sline[4]))
    forces = << get forces from corresponding DFT calc>>
    for i in range(len(forces)):
          print >> ffile, '% 12.8f % 12.8f % 12.8f'%(forces[i][0],
forces[i][1], forces[i][2])
----------------------------------------------------------------------------------------

I don't know if this is helpful. We have working scripts for the WIEN
code if you'd like them, but the basic information is in the above.
FORCES should be in eV/A and the DISP are in fractional coordinates

 Best wishes
   Georg

On 12/03/2010 10:30 AM, Marcin Dulak wrote:
> Hi,
>
> by looking at the latest abinit release one can see that they
> "Print out VASP-style POSCAR and FORCES files, for use with PHON or 
> frophon codes for frozen phonon calculations."
> http://www.abinit.org/documentation/helpfiles/for-v6.4/release_notes/release_notes.html
> Could this way be also interesting for us?
> website of phon: http://www.homepages.ucl.ac.uk/~ucfbdxa/phon/
>
> Marcin
>
>   


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