0. Preface

This tutorial containing four examples illustrates how to realize various forms of independent gradient model based on Hirshfeld partition (IGMH) analyses in Multiwfn. After carefully following this tutorial, you should be able to reproduce all maps in the original paper of IGMH. If you encountered any difficulty in following this tutorial, please feel free to post on Multiwfn official forum: http://sobereva.com/wfnbbs. Background knowledge of IGMH method and its implementation in Multiwfn will not be mentioned in this tutorial, please check original publication of IGMH and corresponding section of Multiwfn manual.

Wavefunction files involved in the following examples can be found in this tutorial package. Many formats containing wavefunction information, such as .wfn, .fch, .molden, .mwfn, etc. and be used as input file for IGMH analysis of isolated system. See beginning of Chapter 4 of Multiwfn manual on how to generate these wavefunction files by various popular quantum chemistry programs, such as Gaussian and ORCA. To perform IGMH analysis for periodic systems, .molden file produced by CP2K is needed, see Section 2.9.2.1 of Multiwfn manual on how to use CP2K program to generate it.

Multiwfn can be freely downloaded at http://sobereva.com/multiwfn, please make sure that you are using the latest version. If you are new to Multiwfn, it is highly suggested to view “Multiwfn quick start.pdf” in Multiwfn package.

VMD version 1.9.3 is utilized in this tutorial, other versions may or may not work, so using version 1.9.3 is recommended. VMD can be freely downloaded at http://www.ks.uiuc.edu/Research/vmd/.

I assume readers are using Windows system (except for quantum chemistry calculations). A few steps in this tutorial may be marginally different in Linux and MacOS systems.

IGM analysis is closely related to IGMH analysis. Abundant examples of IGM analysis can be found in Section 4.20.10 of Multiwfn manual (in fact, all the IGM examples are also applicable to IGMH analysis, you just need to select IGMH analysis instead of IGM analysis in main function 20 of Multiwfn).

Calculation of intrinsic bond strength index (IBSI) is not involved in this tutorial, please check Section 4.9.6 of Multiwfn manual for calculation example.