Dear Jonas,

Thanks for reaching out and being one of the most active users of these early days of the forum. Your question gives us the chance to clarify some aspects of the output file that might not be obvious to non expert users. Below, I will refer to your output file.

Harmonic Frequencies and IR intensities

To compute harmonic frequencies and IR intensities (with the default approach of the Berry phase) the input looks like:

FREQCALC
INTENS
ENDFREQ

In the output file, the following table is printed:

HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH
 EIGENVALUES (EIGV) OF THE MASS WEIGHTED HESSIAN MATRIX AND HARMONIC TRANSVERSE
 OPTICAL (TO) FREQUENCIES. IRREP LABELS REFER TO SYMMETRY REPRESENTATION
 ANALYSIS; A AND I INDICATE WHETHER THE MODE IS ACTIVE OR INACTIVE,
 RESPECTIVELY, FOR IR AND RAMAN; INTEGRATED IR INTENSITIES IN BRACKETS.

 CONVERSION FACTORS FOR FREQUENCIES:
      1 CM**(-1) =   0.4556335E-05 HARTREE
      1 THZ      =   0.3335641E+02 CM**(-1)

 HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH

    MODES         EIGV          FREQUENCIES     IRREP  IR   INTENS    RAMAN
             (HARTREE**2)   (CM**-1)     (THZ)             (KM/MOL)
    1-   1    0.3488E-07     40.9894    1.2288  (A  )   A (     0.40)   A
    2-   2    0.6077E-07     54.1037    1.6220  (A  )   A (     0.96)   A
    3-   3    0.6801E-07     57.2344    1.7158  (A  )   A (     2.45)   A
    4-   4    0.2238E-06    103.8371    3.1130  (A  )   A (    11.47)   A
    [...]

For each mode (or set of degenerate modes) its eigenvalue (in Ha\(^2\)), harmonic frequency (in cm\(^{-1}\) and THz) and irreducible representation get printed. In addition, labels specifying whether the mode is IR/Raman active are also displayed (A and I indicate whether the mode is active or inactive, respectively).

Raman intensities

Raman intensities can be computed via a coupled-perturbed approach by inserting the INTRAMAN keyword followed by the INTCPHF block in the input deck:

FREQCALC
INTRAMAN
INTCPHF
END
ENDFREQ

Raman intensities are computed for each independent component of the polarizability tensor (xx, xy, xz, yy, yz, zz, labeled as "Single Crystal" in the output file) and are also averaged to mimic polycrystalline powder samples (total, parallel polarisation, perpendicular polarisation averages are printed in the output).

POLYCRYSTALLINE ISOTROPIC INTENSITIES (ARBITRARY UNITS)

    MODES    FREQUENCIES           I_tot     I_par    I_perp
  ----------------------------------------------------------------
    1-   1       40.9894 (A  )      0.46      0.27      0.19
    2-   2       54.1037 (A  )      7.35      4.23      3.12
    3-   3       57.2344 (A  )     12.79      8.82      3.96
    4-   4      103.8371 (A  )     13.66      7.89      5.77

SINGLE CRYSTAL DIRECTIONAL INTENSITIES (ARBITRARY UNITS)

    MODES    FREQUENCIES          I_xx    I_xy    I_xz    I_yy    I_yz    I_zz
  ----------------------------------------------------------------------------
    1-   1       40.9894 (A  )    0.00    0.37    0.02    0.63    0.00    0.21
    2-   2       54.1037 (A  )    3.17    0.69    0.00    4.35    3.66   10.05
    3-   3       57.2344 (A  )    3.82    3.54    0.02    3.50    0.03   27.53
    4-   4      103.8371 (A  )    2.57    1.81    0.01   16.25    3.34   19.62

For more details on such polycrystalline averages, please refer to sections 8.4 and 8.7 of the CRYSTAL23 manual.

Raman spectrum

A continuous Raman spectrum can be simulated by use of the RAMSPEC block, as in:

FREQCALC
INTRAMAN
INTCPHF
END
RAMSPEC
END
ENDFREQ

The simulated spectrum is printed in an external file named RAMSPEC.DAT that contains several columns: column 1 with frequencies in cm\(^{-1}\), columns 2-4 with polycrystalline intensities (total, parallel, perpendicular), columns 5-10 with single crystal intensities (xx, xy, xz, yy, yz, zz).

Effect of Temperature and Laser wavelength

The effect of temperature and laser wavelength on computed Raman intensities can be accounted for by use of the RAMANEXP keyword, as in:

FREQCALC
INTRAMAN
INTCPHF
END
RAMANEXP
298 532
RAMSPEC
END
ENDFREQ

Here we set 298 K for the temperature and 532 nm for the laser wavelength. This option modifies the values of all computed Raman intensities (in the output and in the RAMSPEC.DAT file accordingly).

Please, note that other properties (harmonic frequencies and IR intensities) are not affected by this option and thus remain unchanged in the output.

Plots

When CRYSPLOT reads the CRYSTAL output file it only plots the total intensity of the polycrystalline powder model.

When CRYSPLOT reads the RAMSPEC.DAT file it plots all components:

Other plotting tools can be used to plot specific columns of the RAMSPEC.DAT file (e.g., CRYSTALClear, gnuplot).

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