Multiwfn forum

obedientmonk

Member

Registered: Yesterday

Posts: 1

wiberg bond order decomposition with ORCA

Dear Professor Tian,

I wanted to ask if it is now possible to obtain the decomposed Wiberg bond order from the NAO basis using a combination of ORCA and NBO. From reading the manual and searching the forum, I saw that this is possible with Gaussian but had not been implemented with ORCA as of 2021.

If this is still not possible, would you have a suggestion for an alternative that provides a similar decomposed index with Multiwfn?

My objective is to quantify something analogous to the sigma and pi contributions to bond order, similar to the pair fragment contributions in a Mulliken analysis. Ultimately, I aim to combine a QTAIM metric like the delocalization index (DI) with information from NLMOs obtained via NBO, and an overlap/density based metric such as the Mayer or Wiberg bond order, but resolved for specific pairs of orbitals.

One approach I’ve seen in the literature is to examine the overlap of the PNHOs forming the NLMOs. However, I haven’t been able to extract the correct overlap values directly from the raw overlap matrix. If the original approach is not feasible with ORCA, do you have any suggestions for achieving a similar analysis using Multiwfn?

Thank you very much for your work, I'm having a blast learning everything Multiwfn can do

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 2,013

Website

Re: wiberg bond order decomposition with ORCA

Hello,

This decomposition currently is not feasible for ORCA.

However, there are alternative approaches to realize this aim. Mayer bond order from sigma LMO and pi LMO are usually (at least approximately) additive, so you can gain the pi component of Mayer bond order (i.e. pi-bond order) based on LMOs, see Section 4.100.22 of Multiwfn manual on how to do. Also please check Theoretical Chemistry Accounts, 139, 25 (2020) https://doi.org/10.1007/s00214-019-2541-z to gain more information about this idea.