BETAVIB (Vibrational contribution to the SHG and Electro Optic-Effect)

[rbnfritz]

Hi,

I am trying to reproduce the results of an article that specifically focuses on LiNbO3. When using the 'BETAVIB' option, the manual states that the estimation is performed via "d", and the result is printed in the output as:

" VIBRATIONAL POCKELS TENSOR, FREQ.=

DIRECTION CHI(2)"
And

VIBRATIONAL SHG TENSOR, FREQ.=

DIRECTION CHI(2)

But in this article https://onlinelibrary.wiley.com/doi/full/10.1002/pssb.20230005, they (or maybe I misunderstood) said they compute beta using crystal17, and the same is true in this one: https://www.sciencedirect.com/science/article/pii/S0927025623005232. Also, https://journals.aps.org/prb/abstract/10.1103/PhysRevB.107.045140 seems to follow the same rule.

I want to clarify which term is printed in the output file "Using" BETAVIB, and in what unit it is printed?.

Best.
Rubén Fritz.

[aerba]

Hi,

Could you please share your CRYSTAL output file from the BETAVIB calculation? In case you also computed just the electronic term, could you share those output files as well?

The first link you give looks broken: 404 page not found.
Thanks,

[rbnfritz]

Hi,

Thanks. Yes, Fisrt this is the first paper: https://doi.org/10.1002/pssb.202300051.

Here is the Electronic contribution to SHG and EO output file.
Electronic.out

This is the BETAVIB part.
BETAVIB.out
Best.

Rubén Fritz.

[aerba]

Hi,

We have checked the implementation. The values printed in the output of the BETAVIB calculation for SHG and Pockels are expressed in atomic units and correspond to \( \frac{1}{2}{\boldsymbol{ \beta}} \). That is, the factor of \( \frac{2\pi}{V} \) seems to be missing to make them the d tensor. In other words, by multiplying the values in the output by \( \frac{2\pi}{V} \) you should get d.

Please, let me know if you think this makes sense based on the values you get for your system.

Sorry for the confusion.
Hope this helps,

[rbnfritz]

Dear Professor,

Thank you for confirming and clarifying this. For LiNbO3, the prefactor brings the result closer to the values reported in the articles. I will also test other systems.

Thanks once again.
Best regards,
Rubén Fritz.

[aerba]

Excellent, thank you for the quick feedback.