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Antuán

Member

Registered: 2020-11-19

Posts: 11

Evaluating H-bond energies and ELF-¿sigma?

Hi Tian,

first of all, congratulations for the awsome program you are developing and supporting. Thanks. I've seen in the page 359 that you have got a new way to calculate the energy involved in an H-bond. You propose the ??≈−223.08×?(?BCP)+0.7423(for neutral H−bond) formulae, giving in your example 6.2 kcal/mol for this interaction. Well, you compare this value with that obtained from reference Chem. Phys. Lett., 285, 170(1998) in which this energy is evaluated from the potential energy density at the BCP as BE=V(?BCP)/2, arising 8.2 kcal/mol. I agree, this approach probably overestimates the 'real' value. Nevertheless, you omitted another approach reflected in Chem. Phys. Lett., 507, 185(2011), in which BE is evaluated as 0.429×G(?BCP), that is 6.8 kcal/mol, which actually corresponds with a close value to yours.

Second stuff. In pages 412-415 the ELF-sigma appears as ELF-alpha, and talk about alpha orbitals instead of sigma ones. Maybe you have a reason for this although the general decomposition of the ELF function is sigma and pi, isn't it?

Thanks again and good luck! You have done a very good job.
Best regards.
Antonio

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,768

Website

Re: Evaluating H-bond energies and ELF-¿sigma?

Dear Antonio,

Thank you very much for you comment. It should be ELF-sigma rather than ELF-alpha, it is just a typo, I have fixed.

I didn't take 0.429×G(rho(BCP)) into account since it is not as popular as V(rho(BCP))/2 in literatures, indeed it may have better overall accuracy than V(rho(BCP))/2, but a systematical test is not available yet. Given that the type of H-bond systems considered in the CPL paper is relatively limited and especially the calculation level in that work is not satisfactory from today's point of view, I believe the delta-E≈−223.08×rho(rho_BCP)+0.7423 should perform notably better and more useful.

Best,

Tian

Antuán

Member

Registered: 2020-11-19

Posts: 11

Re: Evaluating H-bond energies and ELF-¿sigma?

Hello again,

Many thanks for your quick response. Take also account the table of contents in order to change the sigma-alpha reference.
Keep up the good work.

Best regards,
Antonio