very grateful, I will run it again but not sure what to do here if it aborts again

GiacomoAmbrogio

Dear Ambrogio,

Thank you so much! the problem has been perfectly solved.

All the best,

wang

Hey,

Thank you. It works now. This Forum is a great idea!

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:

Screenshot 2025-03-13 at 12.47.37.png

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

Thank you very much Jacques and Alessandro.
Now it works :).
Best regards
Xavier

Hi,
Thank you very much for your reply!

Best regards,
Masoud

Dear Jacques,

Thank you for your reply which indeed solve the problem.

Best regards
Xavier

Thank you Giacomo Ambrogio.
I am greatful to the CRYSTAL code forum
This will help alot.

Best Wishes

thank you

job314 Yes, it should print the geometry of the last optimization step. Please, be aware that the CIFPRT and CIFPRTSYM options are not as general as one would like them to be. For systems where the primitive and crystallographic cells differ, they may result in an incomplete list of atoms. In those cases, I recommend switching symmetry off with the SYMMREMO option in combination with TESTGEOM, just to generate the .cif files correctly.

Thank you Jacques for your kind help.
This will solve multiple problems of my current work

Regards
R.Zosiamliana

Thank you sir for your kind reply...

job314 Good point! About the shrinking factor: the anisotropic shrinking factor in CRYSTAL does not work properly for those calculations where the symmetry of the system may change (for instance in frequency calculations, FREQCALC, where displaced nuclear configurations are explored, or elastic calculations, ELASTCON, where the lattice is strained, etc.). So in general, I personally tend to avoid using an anisotropic shrinking factor.

However, for symmetry-preserving calculations (such as SCF, OPTGEOM, EOS) the use of an anisotropic shrinking factor should be fine.

Sorry, I have been working fiercely on these cases, must have overwritten many times. Several EOS cases run out of cycles such as this after 102 cycles abive, including this one when I start range at 0.92 lattice constant (according to the online manual examples). Some of these problems went away when I narrowed the range, e.g. start at 0.96

thank you

Hi,

In CRYSTAL23, the anharmonicity of a given vibration mode - or of a set thereof - can be computed via: I) the evaluation of cubic and quartic interatomic force constants (in the basis of the normal modes) followed by II) the solution of the nuclear Schroedinger equation with either the vibrational self-consistent field (VSCF) or vibrational configuration interaction (VCI) method.

Details on the actual implementation of steps I) and II) can be found here:

I) Anharmonic force constants

II) VSCF and VCI for solids

Step-by-step, the procedure is as follows:

Geometry optimization to fully relax atomic positions within the cell (OPTGEOM keyword); Harmonic frequency calculation (FREQCALC keyword); Selection of the normal modes for which the anharmonic correction is to be computed (for instance, in your case, those corresponding to C-H stretching vibrations); Calculation of cubic and quartic interatomic force constants for the selected modes + VSCF (or VCI) calculation of anharmonic states.

As an example, let' s assume that C-H stretching vibrations correspond to modes 15-20 in the list generated from the harmonic calculation (that is, there are 6 different C-H stretching modes). The input for steps 3. and 4. above would read:

FREQCALC RESTART ANHAPES 6 15 16 17 18 19 20 3 0.9 VSCF END

that is, we restart the harmonic frequency calculation, and where 6 is the number of modes, 15 16 17 18 19 20 are the selected modes, and 3 0.9 are two parameters specifying the numerical approach used for the evaluation of cubic and quartic force constants.

Please, note that with such a calculation not only the "intrinsic" anharmonicity of each selected mode is evaluated but also the couplings among all selected modes. If, instead, one just wants to compute the "intrinsic" anharmonicity with no couplings, independent calculations can be run, one per each selected mode.

Visit this page for a tutorial on anharmonic calculations in CRYSTAL

Hi,

The presence of imaginary frequencies is a sign that the geometry is not a minimum of the potential energy surface (PES). In general, this may due to two main factors:

1) A somewhat loose overall numerical precision in the geometry optimization + harmonic frequencies calculation. Here, it seems that you have already explored a few parameters. We can distinguish between parameters governing the overall numerical precision of the SCF + forces calculations, and those that are specific to the evaluation of the Hessian:

1.1) Precision of SCF+forces

One may increase a bit the thresholds for the screening of two-electron integrals (TOLINTEG keyword), switch-off the bipolar approximation (NOBIPOLA keyword), increase the shrinking factor (SHRINK keyword), use a denser grid for numerical integration of the exchange-correlation term (see XLGRID, XXLGRID keywords), tighten the convergence criteria for the SCF (setting TOLDEE to 10 or 11 for instance), tighten the convergence criteria for the geometry optimization step (see TOLDEG and TOLDEX keywords).

1.2) Numerical evaluation of the Hessian

In many cases, a more numerically stable evaluation of the Hessian is achieved by use of a two-sided finite difference approach (rather than the default one-sided approach). This can be activated with the NUMDERIV keyword within the FREQCALC input block as follows:

FREQCALC NUMDERIV 2 ENDFREQ

2) The presence of symmetry-constraints that prevent the optimizer to get to the minimum of the PES. If this is the case, removing symmetry constraints may be key to reach the minimum. This can be done by use of the SYMMREMO keyword (to be inserted in the geometry input block).

Dear Giacomo, it worked fine. Thank you very much!