Hi all,

I have a question regarding dynamical matrix calculation using LAMMPS. In

the USER-PHONON/examples/1-1D-mono/ directory I calculated the dynamical

matrix at q=(0.5 0 0) and the dynamical matrix it produced is given below:

# q = [0.5 0 0]

3.9469 0

But since the system is 1-dimensional and also it has 1-atom basis, then

the dynamical matrix should be a single number in stead of a 1by2 matrix.

This happens all the time. If I calculate the dynamical matrix of a 2-D

system with 2-point basis, then it is a 4by8 matrix in stead of a 4by4

matrix (given below):

# q = [0.5 0 0]

842.997 0 40.0807 0 -680.244 0 -317.185 0

40.0807 0 759.033 0 -318.323 0 -284.777 0

-680.244 0 -318.323 0 843.284 0 40.7265 0

-317.185 0 -284.777 0 40.7265 0 756.014 0

I don't understand what is the reason behind it. Where does these

zero-columns come from all the time? If I want to calculate the

eigenvectors of the dynamical matrix, then what should be the actual

matrix?

Best Regards