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.