ABINIT Discussion Forums

Posted: **Sun Sep 01, 2013 7:27 pm**

Dear users,

How can i compute IR absorption and reflectivity spectrum for polar materials?

Posted: **Mon Sep 02, 2013 9:00 am**

Hi!

I'm not 100% sure, but I think that you can find it in Ph. Ghosez's PhD thesis (available on web).

Best regards,

Igor

Posted: **Sat Sep 28, 2013 7:30 pm**

Thank you for reply. I saw that thesis. But it’s not much clear that what equation they use to build IR spectrum. I think that they have used oscillator strengths of Abinit output to build IR spectrum. Like this

Code: Select all

 Oscillator strengths (in a.u. ; 1 a.u.=253.2638413 m3/s2)
 Mode number.       xx          yy          zz          xy          xz          yz 
;   1     Real    2.4964E-22  1.6906E-25  2.1185E-24 -6.4964E-24  2.2997E-23 -5.9845E-25
;         Imag    0.0000E+00  0.0000E+00  0.0000E+00  0.0000E+00  0.0000E+00  0.0000E+00
;   2     Real    1.6909E-25  2.7737E-23  1.6906E-25  2.1657E-24 -1.6908E-25 -2.1654E-24
;         Imag    0.0000E+00  0.0000E+00  0.0000E+00  0.0000E+00  0.0000E+00  0.0000E+00
;   3     Real    1.4373E-22  1.6906E-25  2.7737E-23 -4.9294E-24 -6.3140E-23  2.1655E-24
;         Imag    0.0000E+00  0.0000E+00  0.0000E+00  0.0000E+00  0.0000E+00  0.0000E+00
;   4     Real    1.2265E-04  1.0561E-26  8.9770E-24  1.1381E-15 -3.3182E-14 -3.0791E-25
;         Imag    0.0000E+00  0.0000E+00  0.0000E+00  0.0000E+00  0.0000E+00  0.0000E+00
;   5     Real    1.0559E-26  1.2265E-04  1.0559E-26 -1.1380E-15 -1.0559E-26  1.1380E-15
;         Imag    0.0000E+00  0.0000E+00  0.0000E+00  0.0000E+00  0.0000E+00  0.0000E+00
;   6     Real    1.3231E-25  1.0559E-26  1.2265E-04 -3.7378E-26  4.0285E-15 -1.1380E-15
;         Imag    0.0000E+00  0.0000E+00  0.0000E+00  0.0000E+00  0.0000E+00  0.0000E+00

How do I have IR spectrum using these oscillator strengths?
If I take the summation of any direction of it, it can be IR intensity of particular direction?
For example: if I take sum of oscillator strength by x direction, IR intensity will be 1.2265E-04 for mode 4.
It is 1.2265E-04 for mode 5 for y direction.
It 1.2265E-04 for mode 6 for z direction.
Is that right to build IR spectrum using Abinit output?
Please help me

ABINIT Discussion Forums

IR spectrum

IR spectrum

Re: IR spectrum

Re: IR spectrum