Understanding the .eig file

GULP
1

Dear. Julian,

I hope this finds you well there. I am writing to inquiry about the GULP eigenvector output. I am new to GULP output files, therefore I wonder the meaning of some rows in .eig file.

  1. For each mode, I have obtained the similar layout as

    Mode      1
     110.187654
 -0.163350  0.282929  0.000000      0.282932 -0.490050 -0.000001
 -0.326701  0.565860 -0.000001      0.000000 -0.000000 -0.000000
 -0.067578  0.117049  0.000000      0.117049 -0.202735 -0.000000
 -0.135157  0.234098 -0.000000      0.000000 -0.000000  0.000000
Mode      2
     158.804383
 -0.025874 -0.014936  0.338018      0.044816  0.025870 -0.585468
  0.051749  0.029873  0.676039      0.000000  0.000000 -0.000000
  0.016826  0.009714  0.097327     -0.029143 -0.016826 -0.168576
 -0.033652 -0.019429  0.194655      0.000000  0.000000  0.000000
 ......

    So is it the 110.187654 refers to the energy and what about the meaning of each column for the following four rows?

  2. I noticed that there are repeated modes in the .eig file, for example, what is the relationship or difference for the mode 1 shown in the file?

    K point at   0.500000  0.000000  0.000000 in BZ 
Mode      1
     110.187654
 -0.163350  0.282929  0.000000      0.282932 -0.490050 -0.000001
 -0.326701  0.565860 -0.000001      0.000000 -0.000000 -0.000000
 -0.067578  0.117049  0.000000      0.117049 -0.202735 -0.000000
 -0.135157  0.234098 -0.000000      0.000000 -0.000000  0.000000
.
.
.
.
Mode     12
     610.668288
  0.039250  0.022664 -0.019452     -0.067984 -0.039255  0.033693
  0.078501  0.045327  0.038905     -0.000000 -0.000000 -0.000000
 -0.303172 -0.175042 -0.003643      0.525112  0.303184  0.006310
 -0.606347 -0.350086  0.007287      0.000000  0.000000  0.000000
K point at   0.482759  0.000000  0.000000 in BZ 
Mode      1
     110.033795
  0.132581 -0.229636 -0.000000     -0.298560  0.517119  0.000001
  0.323307 -0.559982  0.000001     -0.046779  0.081023 -0.000000
  0.055065 -0.095375 -0.000000     -0.123502  0.213911  0.000000
  0.133799 -0.231746  0.000000     -0.019564  0.033886  0.000000

Looking forwards to your early reply.

Thanks,

Catherine

2

Hi Catherine,

The format of the output is as follows:

Mode number
Frequency (in wavenumbers)

and then for each atom (one per line) there are the real x, y and z eigenvector components, followed by the imaginary x, y, and components (if this isn’t the gamma point).

The reason for multiple sets of output (both starting with Mode 1) is that there are often multiple K points in the Brillouin zone. The K point should be indicated by the line in the output that you see in 2.

Hope that helps,
Julian

3

Hi Julian,

Thanks a lot for your message. I got it.

Best regards,

Catherine