The ABINIT Users Mailing List ( CLOSED )

[Horacio W L Alves <hwlalves@funrei.br>]

Dear Kwan-Woo Lee,

You did understanding almost correct. The recipe you have mentioned on your
e-mail works well in cubic structures.
I did the same question one or two months ago and Xavier gave a "light" to
this kind of calculation.
i) You only need the gamma-point DDB calculation;
ii) In the ifc input file, change the line corresponding to "brav" input to
1(it holds for lower symmetries in this case, and not only for cubic systems);

iii) Change the grid to the corresponding one of HCP structure(for the
dispersion);
iv) Run the ifc code and finally get the phonon dispersion - it works well -
it is all you need in your case

Good continuation,

Horacio W. Leite Alves



Kwan-Woo Lee wrote:

> Dear ABINIT Users,
>
> I have a few questions.  Could you help me?
>
> 1) Did you use the ifc-code in order to obtain a phonon dispersion
> relation?
>   I don't exactly understand the required step.
>  First, obtain the DDB files using ABINIT main code at a few symmetry
> points.
>  Second, merge the DDB files using mrgddb code.
>  Third,  obtain the final results using ifc code.
>
> Is the  step correct ?
>
>
> 2)  Is there  one that have ever tried to obtain the phonon frequency, with
> hcp-structure, contained E-field perturbation?
> I obtained it of several materials with the fcc structure, however I have
> not solved the problem
> of hcp-structure.  This is a input file (also attached) of LiB with
> hcp-structure.  (For non-E field perturbation,  I obtained the phonon
> frequencies)
>
> ###########################################################################
> ndtset   3
>
> # Specific to ground state calculation
> kptopt1    1                     #1,2 or 3
> mkmem1     0
> tolvrs1    1.0d-18
>   iscf1    5
>
> # Response Function calculation : d/dk
> rfelfd2    2
>  rfdir2    1  0  0           # In the x-direction.
>
> nqpt2      1
>  qpt2      0.0  0.0  0.0     # For a Gamma point
>
> getwfk2    -1
> kptopt2     2
>
> iscf2      -3
> tolwfr2    1.0d-22
>
> # To calculate RF, with q=0: E-field perturbation
> rfphon3     1
> rfatpol3    1   4
> rfelfd3     3                 # only the generation of the first-order
> response
>                                 # to the electric field
> rfdir3      1  1  1
> kptopt3     2
>
> nqpt3       1
>  qpt3       0.0  0.0  0.0      # Gamma point
>
> getwfk3    -2                  # Read the previous result(groundstate Cal.)
> getddk3    -1                  # Using the ouput of the dataset2
>
> tolvrs3     1.0d-10
>   iscf3     5
>
> ######################################################Common Input
> variables
> #Definition of the unit cell
> acell 2*4.022  2.796 angstrom
>
> rprim  0.86602540378  0.500  0.000  # Primitive vectors
>       -0.86602540378  0.500  0.000
>        0.000          0.000  1.000
>
> #spgroup     194                     # the number of space group
> # brvltt       1                          # from the table
> chkprim       0
> occopt        4
>  ntype   2           # There are only three types of atom
> zatnum  3   5      # The keyword "zatnum" refers to the atomic number of
> the
>                         # possible type(s) of atom.
>
> #Definition of the atoms
> natom  4            # There are four atoms
>  type  2  2  1  1   #
>  xred
>    0.00 0.00 0.00   # Triplet giving the reduced coordinates of atom 1, in
> Bohr
>    0.00 0.00 0.50
>    0.6666666666666666667 0.3333333333333333333 0.00 # of atom 2, in Bohr
>    0.3333333333333333333 0.6666666666666666667 0.50
>
> #Definition of the planewave basis set
> #ecut 10.0         # Maximal plane-wave kinetic energy cut-off, in Hartree
> ecut  5.0
> dilatmx 1.10
>
> # Gives the number of band
> nband   8           # Not determined.
>
> #Definition of the k-point grid( afther testing, determined.)
> #prtkpt  1          # to genertate "kptrlatt" and "shiftk"
> kptrlatt  2   0   0
>            0   2   0
>            0   0   3
> nshiftk  1
> shiftk  0.00000000  0.00000000  5.00000000E-01
>
> #Definition of the SCF procedure
> nstep 40           # Maximal number of SCF cycles
>
> ###########################################################################
>
> If you have any hint,  please let me know it.
> I will very apprecite for it.
>
> Sincerely,
>
> Kwan-Woo Lee
>
>   ------------------------------------------------------------------------
>                     Name: lib_hcp.in
>    lib_hcp.in       Type: other/unknown
>                 Encoding: base64
>              Description: lib_hcp.in