Vs - Vibrations of crystals (space group) => preparation

This options works similarly to the Vm option. The menu is this:

>>>>>>>>>>>>>>>>>>>>>>>>>>><<<<<<<<<<<<<<<<<<<<<<<<<<<

<<SUPERCELL>> --- CURRENT lattice vectors: --

#          SUPERCELL             PRIMITIVE CELL       EXTENTION

(1) 10.88160 0.00000 0.00000 | 10.88160 0.00000 0.00000 |1 0 0

(2) 0.00000 10.88160 0.00000 | 0.00000 10.88160 0.00000 |0 1 0

(3) 0.00000 0.00000 10.88160 | 0.00000 0.00000 10.88160 |0 0 1

========= CHOOSE an OPTION:

Su. General "breeding": construct a supercell <= undefined

------- G e n e r a l I n f o r m a t i o n ------

-------- G e n e r a l S e t t i n g s --------

UU. ****** RESTORE the original lattice ******

Am. Atomic masses for every species:

    28.08600 [Si] 15.99940 [ O]

XY. Format of <movie.xyz> file is for Xmol

Da. Distortion amplitude: 0.01000

Nd. Number of displacements (for [Au] only): 2

Hs. H atoms to be added to <movie.xyz> file: NO

Q. Proceed/Quit

-----> Choose an appropriate option:

You should first choose the cell extention using the option Su, identical to the one in the M-menu, Section 2.6.5. When you are done, the menu changes:

>>>>>>>>>>>>>>>>>>>>>>>>>>><<<<<<<<<<<<<<<<<<<<<<<<<<<

<<SUPERCELL>> --- CURRENT lattice vectors: --

#        SUPERCELL                PRIMITIVE CELL        EXTENTION

(1) 10.88160 0.00000 0.00000 | 10.88160 0.00000 0.00000 |1 0 0

(2) 0.00000 10.88160 0.00000 | 0.00000 10.88160 0.00000 |0 1 0

(3) 0.00000 0.00000 10.88160 | 0.00000 0.00000 10.88160 |0 0 1

========= CHOOSE an OPTION:

Su. General "breeding": construct a supercell <= Done!

Fx. Specify which orbits to fix

Ir. Collect info about symmetry adapted vectors <- undefined

------- G e n e r a l I n f o r m a t i o n ------

Co. Show general geometry information about orbits

Or. Show detailed information about given orbit

Kp. Show all k-points

Sy. Show the symmetry group info

-------- G e n e r a l S e t t i n g s --------

UU. ****** RESTORE the original lattice ******

Am. Atomic masses for every species:

28.08600 [Si] 15.99940 [ O]

XY. Format of <movie.xyz> file is for Xmol

Da. Distortion amplitude: 0.01000

Nd. Number of displacements (for [Au] only): 2

Hs. H atoms to be added to <movie.xyz> file: NO

Q. Proceed/Quit

-----> Choose an appropriate option:

It is now possible to recognise the familiar structure of the Vm- and the Vc-menus. The option Sy is, however, different now: it shows $\mathbf{k}$ vectors corresponding to each of the irreducible representations of the group $G$ of internal translations, see Section 2.6.8.1. The option Kp gives similar information.

To accomplish the first stage of the phonons calculation, follow the same steps as in the previous two cases:

• first, fix orbits (if necessary) with Fx
• use Ir
• choose the number of displacements (1,2 or 4) in Nd and the distortion amplitude in Da, or leave the default values
• run the automatic option Au, which will prompt you to select the DFT code and specify the name of the input file corresponding to the undistorted geometry
• edit (if necessary) and then run the run_DFT_script to calculate the forces for each input file
• run options V2 or V3 of the main menu to calculate phonon frequencies, normal coordinates and the phonon DOS.