A new method for visually studying both chemical bonds and weak interactions named Interaction Region Indicator (IRI) proposed by me has been available in Multiwfn, and the corresponding manuscript now can be accessed via ChemRxiv preprint server, see: http://doi.org/10.26434/chemrxiv.13591142. IRI is not only able to vividly exhibit weak interactions as reduced density gradient (RDG), but can also nicely reveal all kinds of chemical bond regions. Please check the ChemRxiv manuscript and supplemental material. This work has been submitted to an academic journal.

A very detailed tutorial showing how to perform IRI analysis in Multiwfn is available: //www.umsyar.com/multiwfn/res/IRI_tutorial.zip.

I hope IRI will become a new popular method for computational chemists in studying interatomic interactions in chemical systems.

Tian Lu