Phonon eigenvectors from ASE and GULP

ASE
1

Hi,

The Phonon class has “write_modes” fuction which generates .traj files.
(1) Does this file generate modes which is the eigenvector in the .traj file?
(2) If yes, then how could I read/visualize such file ?

Also,

I am attaching a comparative file of Dynamical matrix produced from GULP and ASE. Please find the attached compare_Dyn_mat.dat file.
compare_Dyn_mat.dat (6.7 KB)

The eigenvetors coming from the GULP(GULP uses analytic second derivatives wherever possible, which is why there is no need for finite differences) is what I need for my future calculations of thermal conductivity.

The Dynamical matrix from which the eigenvectors are coming from the GULP for a wave-vector say for eg. k = [0.5,0.5,0.25] (with the use of keyword “pfinite” for finite differnce technique as you had suggested earlier) is slightly different than what ASE is producing.

ASE uses the same finite difference technique in order to calculate the Dynamical matrix but the off-diagonal terms sign and small imaginary values appear.

Question 2:Could you suggest me a possible change that may help me in producing the exact dynamical matrix from ASE as is coming fro
[compare_Dyn_mat.dat|attachment]
m the GULP?

Thank you in advance.

2

Hi abhikeern,

(1) Does this file generate modes which is the eigenvector in the .traj file?

Yes

(2) If yes, then how could I read/visualize such file ?

ase gui filename.traj, or use ase convert to convert to another format (see ase info --formats for list).

(with the use of keyword “pfinite” for finite differnce technique as you had suggested earlier)

I’m not aware of previous communication on this

Question 2:Could you suggest me a possible change that may help me in producing the exact dynamical matrix from ASE …

The phonons object has compute_dynamical_matrix().

https://wiki.fysik.dtu.dk/ase/ase/phonons.html