Multiwfn forum

yasiraltaf

Member

Registered: 2019-10-30

Posts: 3

QTAIM/ELF/Coordination number/Atom-atom energetic interaction/multiwfn

Hi

I have to calculate hapticity and atom-atom energetic interactions in some host-guest complexes where a metal (M) cation is embedded in cyclophane cavity. I assume hapticity means coordination number of metal cations but not sure about atom-atom energetic interactions (we already carried out energy decomposition analysis and presented with the results but still was asked for this one). Moreover, I have to calculate electron localization function (ELF) in all the cases.

Do I need to calculate atom-atom energetic interaction and ELF for every individual M-C interaction? We assume the interactions in our system are weak based on some other results, so my understanding is that we should carry out the above-mentioned analysis just to see overall behaviour of metal cation inside the cyclophane cavity. Any explanation would be highly appreciated.

Moreover, we'll carry out these studies in Multiwfn. Except ELF, I would request explanation about how to carry out the study of coordination number and electron-electron energetic interaction in this software as there is a mentioning of these two properties in the manual but method not given.

Thanks a lot

Yasir

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,830

Website

Re: QTAIM/ELF/Coordination number/Atom-atom energetic interaction/multiwfn

The way of calculating atomic coordinate number is given in Section 3.100.9 of Multiwfn manual.

Currently in Multiwfn there are two ways of quantifying pairwise weak interaction, the first one is performing energy decomposition analysis based on forcefield, see Section 3.24.1 for introduction and Section 4.21.1 of example. Another way is calculating δ index in the IGM framework, see Section 3.23.5 for introduction and Section 4.20.10 for example.

In Multiwfn there are many other ways that can study weak interactions, see Section 4.A.5 for an overview.

ELF is not suitable for studying weak interaction. It focuses on characterizing chemical bonds.

yasiraltaf

Member

Registered: 2019-10-30

Posts: 3

Re: QTAIM/ELF/Coordination number/Atom-atom energetic interaction/multiwfn

Hi Tian
Thanks for your response. I calculated the coordinate number of metals and the results look highly erroneous. Even for experimentally known complexes with 18 coordination number (in host-guest complexes), the value which I got is 0. Is it what I doing something wrong or it's the limitation of connectivity index?

Thanks

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,830

Website

Re: QTAIM/ELF/Coordination number/Atom-atom energetic interaction/multiwfn

The function of calculating coordinate number that I previously mentioned is only suitable for chemical bonding, if your interaction belongs to weak interaction, then this function is unable to give useful result.

Probably the function introduced in Section 3.200.9 is useful for you, in this function you can manually define a distance threshold used for estimating coordinate number.