Dear LAMMPS users and Developers,
I am working in calculating IR of diamond. The key of calculating IR spectra is calculating the dipole moment. But there is no charge in the diamond. I found there were molecular and liquid IR spectra with LAMMPS simulation. So I want to know if the LAMMPS can calculate IR spectra of crystal or solid？If it can, and how?
I would appreciate it if you can help me. Thank you!
Yours sincerely,
[
taiqiaoliu
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to compute accurate IR spectra with proper intensities you need quantum calculations, since you need to determine the transition moments, i.e. whether a specific peak is IR (or Raman) active and how strong it would couple.
but you can determine the possible frequencies by taking the fourier transform of an auto-correlation function from about any property that is related to the motion of particles, not just the total dipole moment of the sample, e.g. the velocities of the individual atoms. LAMMPS can help with the first part.
there should be information about this in MD text books and the published literature.
axel.
