CRYSTAL – “***********” in Sum Tensor of Vibrational Contributions to Static Polarizability (Raman, CNT 26,0)

[Drmajouri2025]

I am performing Raman frequency calculations in CRYSTAL for a (26,0) carbon nanotube. The geometry and SCF dont converge correctly, and the vibrational calculation runs without crashing.

However, in the output I obtain:
SUM TENSOR OF THE VIBRATIONAL CONTRIBUTIONS TO THE STATIC POLARIZABILITY TENSOR

******************* -0.00000 0.00000
-0.00000 2575.62713 0.00000
0.00000 0.00000 2575.62713

What does the “***********” mean in this context ?
Or this is due of the not completed optimization ?

[GiacomoAmbrogio]

Hi Drmajouri2025,
When performing frequency calculations, it is essential that the geometry is fully optimized with the SCF properly converged. If the structure is not at a true stationary point of the potential energy surface, the computed second derivatives (Hessian) can lead to unreliable frequencies and response properties.

Regarding the *******************, these typically means that the value exceeds the field width allocated in the printing format. In other words, the number is too large (or not representable) within the fixed output format, so it is replaced by stars.

However, in your case, since the geometry did not converge properly, the appearance of stars is very likely due to numerical problem rather than just a harmless formatting issue.

I would strongly recommend:

• First ensuring tight SCF convergence (you can also increse TOLDEE and/or TOLINTEG parameters).
• Fully optimizing the geometry until forces are below the required thresholds.
• Verifying that the optimized structure has no imaginary frequencies.
• Only then performing the Raman calculation.

[Drmajouri2025]

Thank you, this is too clear and very helpful.