1. Preface

This tutorial briefly introduces how to perform various forms of interaction region indicator (IRI) analyses in Multiwfn. After carefully following this tutorial, you should be able to reproduce all maps in the original paper of IRI. If you encounter any difficult in following this tutorial, please feel free to post on Multiwfn official forum: http://sobereva.com/wfnbbs.

All wavefunction files can be found in this tutorial package. See beginning of chapter 4 of Multiwfn manual on how to generate wavefunction files by various quantum chemistry programs. Multiwfn can be freely downloaded at http://sobereva.com/multiwfn, please use the version updated after 2021-Jan-16. It is possible that in future versions some details will be slightly different to this document, at that time please check program prompts on screen and manual of corresponding version. VMD version 1.9.3 is utilized in this tutorial, other versions may or may not work. VMD can be freely downloaded at http://www.ks.uiuc.edu/Research/vmd/.

IRI analysis is closely related to RDG analysis (also known as NCI analysis), very detailed introduction about RDG analysis can be found in Section 3.23.1 and 4.20.1 of Multiwfn manual, since many discussions in these sections are also applicable to IRI analysis, you are also suggested to look at them.

IRI descriptors extend IRI analysis from qualitative to quantitative, which is very important but not covered in this tutorial, examples are given in Section 4.200.14 of Multiwfn manual.