Multiwfn forum / how to compute " bond stretching force constant"?

Re: how to compute " bond stretching force constant"?

dummy@example.com (saeed_E) — Fri, 12 Sep 2025 17:53:46 +0000

Dear Tian,
Thank you very much for your highly valuable guidance.
Best regards,
Saeed

Re: how to compute " bond stretching force constant"?

dummy@example.com (sobereva) — Tue, 09 Sep 2025 06:38:24 +0000

This depends on your practical purpose. I suggest reading original paper of Seminario (International Journal of Quantum Chemistry: Quantum Chemistry Symposium 30, 1271 -1277 (1996)), and review of relaxed force constant (Chem. Soc. Rev., 2008, 37, 1558–1567).

Re: how to compute " bond stretching force constant"?

dummy@example.com (saeed_E) — Mon, 08 Sep 2025 18:12:10 +0000

Thank you very much.
I do not know which of "Sobtop" or "Compliance" should be used. Indeed, I do not know what the difference is between the force constant estimated by your code and by the Compliance one. Could you please let me in more details?

Re: how to compute " bond stretching force constant"?

dummy@example.com (sobereva) — Mon, 08 Sep 2025 17:33:43 +0000

Bond force constant can be calculated by my code Sobtop (http://sobereva.com/soft/Sobtop) based on Gaussian .fch file produced by freq task (namely this .fch file contains Hessian), Seminario and modified Seminario methods are supported in Sobtop for this purpose.

If you need relaxed force constant, you can use http://www.oc.tu-bs.de/Grunenberg/compliance.html

This is no other post about AIMD.

how to compute " bond stretching force constant"?

dummy@example.com (saeed_E) — Mon, 08 Sep 2025 09:48:29 +0000

Dear Tian,
As you know better than I, the bond stretching force constant (k) is one of the molecular properties with wide applications, and it is well correlated with many molecular characteristics.
If possible, please let me know how this quantity can be calculated through routine computational approaches.
I would be very grateful if your guidance includes detailed explanations, or please refer me to a detailed and comprehensive reference.

Please also let me know the address of ALL very informative and valuable posts/articles you have prepared about molecular dynamics or meta-dynamics using Orca/xtb/Gaussian. For instance, I found one very nice and informative of such articles (HTTP://sobereva.com/576) and I am extremely interested in all such articles.

Thanking you in advance.
With utmost regards,
Saeed