phono3py/doc/turbomole.md

(turbomole_interface)=

TURBOMOLE & phono3py calculation

The riper module of TURBOMOLE can be used to study periodic structures. An example for TURBOMOLE is found in the example/Si-TURBOMOLE directory.

To invoke the TURBOMOLE interface, --turbomole option has to be always specified:

% phono3py --turbomole [options] [arguments]

When the file name of the unit cell is different from the default one (see :ref:default_unit_cell_file_name_for_calculator), -c option is used to specify the file name. TURBOMOLE unit cell file parser used in phono3py is the same as that in phonopy. It reads a limited number of keywords that are documented in the phonopy web site (http://phonopy.github.io/phonopy/turbomole.html#turbomole-interface).

(turbomole_workflow)=

Workflow

In the example Si-TURBOMOLE, the TURBOMOLE input file is control. This is the default file name for the TURBOMOLE interface, so the -c control parameter is not needed.

1. Create supercells with displacements (2x2x2 conventional cell for 3rd order FC and 3x3x3 conventional cell for 2nd order FC)

   % phono3py --turbomole --dim="2 2 2" --dim-fc2="3 3 3" -d
   

   111 supercell directories (supercell-00xxx) for the third order force constants are created. In addition, one supercell directory (supercell_fc2-00001) is created for the second order force constants.

2. Complete TURBOMOLE inputs need to be prepared manually in the subdirectories.

   Note that supercells with displacements must not be relaxed in the force calculations, because atomic forces induced by a small atomic displacement are what we need for the phonon calculation. To get accurate forces, $scfconv should be 10. Phono3py includes this data group automatically in the control file. You also need to choose a k-point mesh for the force calculations. TURBOMOLE data group $riper may need to be adjusted to improve SCF convergence (see example files in subdirectory supercell-00001 for further details)

   Then, TURBOMOLE supercell calculations are executed to obtain forces on atoms, e.g., as follows:

   % riper > supercell-00001.out
   

3. Collect forces in FORCES_FC3 and FORCES_FC2::

   % phono3py --turbomole --cf3 supercell-*
   % phono3py --turbomole --cf2 supercell_fc2-*
   

   disp_fc3.yaml and disp_fc2.yaml are used to create FORCES_FC3 and FORCES_FC2, therefore they must exist in current directory. The Si-TURBOMOLE example contains pre-calculated force files.

4. Calculate 3rd and 2nd order force constants in files fc3.hdf5 and fc2.hdf5:

   % phono3py --turbomole --dim="2 2 2" --dim-fc2="3 3 3" --fc-symmetry
   

   --sym-fc is used to symmetrize second- and third-order force constants.

5. Thermal conductivity calculation:

   % phono3py --turbomole --primitive-axis="0 1/2 1/2  1/2 0 1/2  1/2 1/2 0" --fc3 --fc2 --dim="2 2 2" --dim-fc2="3 3 3" --mesh="20 20 20" --br
   

   --primitive-axis is used to get the results for the primitive 2-atom cell --br invokes the Relaxation Time Approximation. Carefully test the convergence with respect to --mesh!