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exercises:2018_ethz_mmm:infrared_2018 [2018/04/20 14:09] dpasseroneexercises:2018_ethz_mmm:infrared_2018 [2020/08/21 10:15] (current) – external edit 127.0.0.1
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 ===== 2. Task: Computing vibrational spectra using DFTB molecular dynamics ===== ===== 2. Task: Computing vibrational spectra using DFTB molecular dynamics =====
  
-You will find a fortran program in the repository, called ** dipole_correlation.f90 ** +You will find a fortran program in the repository, called ** dipole_correlation.f90 ** . This is already compiled and the executable is dipole.x.
  This program computes the correlation function of the (derivative of) the dipole moment and performs the Fourier transform.  This program computes the correlation function of the (derivative of) the dipole moment and performs the Fourier transform.
  
 Run ** cp2k ** with the ** md*.inp ** input files (for the two molecules). Note that the dipole moment and derivatives are extracted from simulation and saved in a file dip*traj (check the input). Run first 5000 steps, then edit the file dipole.in  and run ** ./dipole.x < dipole.in **. Run ** cp2k ** with the ** md*.inp ** input files (for the two molecules). Note that the dipole moment and derivatives are extracted from simulation and saved in a file dip*traj (check the input). Run first 5000 steps, then edit the file dipole.in  and run ** ./dipole.x < dipole.in **.
 +
 This will generate the autocorrelation function of the dipole derivative (why?) and its Fourier transform (frequency domain). This will generate the autocorrelation function of the dipole derivative (why?) and its Fourier transform (frequency domain).
  
-<note important>  - Check the result. Is it satisfactory with respect to the DFT static calculation and literature? Why?+<note important>  - Check the result. **gnuplot** with the command **plot "file" u 1:2 w l** will help. Is it satisfactory with respect to the DFT static calculation and literature? Why?
   - Run 40000 more steps. Check the new results. Discuss what you obtained. Discuss the behavior of the autocorrelation in the time domain.   - Run 40000 more steps. Check the new results. Discuss what you obtained. Discuss the behavior of the autocorrelation in the time domain.
 +  - ** WEB SITE [[https://www.cfa.harvard.edu/hitran/vibrational.html|Vibrational modes]] **
 </note> </note>
exercises/2018_ethz_mmm/infrared_2018.1524233343.txt.gz · Last modified: 2020/08/21 10:15 (external edit)