A Quantum Chemical Topology Software

TopChem2 is a standalone program specifically designed for the topological analysis of the electron density/the electron localization function (ELF)/the Molecular Electrostatic Potential (MEP) functions from three-dimensional cube grids link1 link2 or from wfn gaussian files link3 . The program makes use of a full algorithm enabling to numerically assign the data points grids to basin volumes. It is distributed as binary only, free of charge.

Easily usable in command-line, automatic and robust.

by J. Pilmé, Laboratoire de Chimie Théorique - Sorbonne Université
contact email:

Basin and Population Analysis

TopChem2 looks for all basins of the gradient scalar field along the descent trajectories from attractor points. The algorithm is similar to the one used by the TopMod program [Computers & chemistry, 23 (6), pp. 597-604, 1999]. Each grid point is assigned to a basin volume, assignment codes are stored in an array.

chgcar ice

Licence agreement

Using TopChem2 requires agreement to the following conditions upon receipt of the program:

  • I understand that copyright and intellectual property rights are retained by Julien Pilmé (Sorbonne University, Paris). TopChem2 is provided without any expressed or implied warranties of any kind.
  • I agree to use this software for no profit purpose and I will not incorporate any part of the code in a commercial software. Neither TopChem2 nor any of its components may be sold, redistributed, repackaged, bundled, copied, modified, disassembled or reverse engineered in any form, either in whole or in part, without the explicit, written consent of Julien Pilmé.
  • In no event shall the author be held liable for any damages of any kind arising directly or indirectly from the download, installation or use of TopChem2. Its compatibility with or effect on any computer hardware or software, or the reliability or accuracy of any results it produces.
  • Download

    System requirements : Linux (GLIBC 2.4 or later), Intel/AMD (x86) processor(s), 64 bit

    TopChem2 64-bit: Download


    A. Open a linux terminal and extract the files from the tar archive:

                 > tar -xvf TopChem2_cube64.tar.gz

    B. Change the directory to where the files are located:

                 > cd INSTALL_TOPCHEM64

    C. Run the bash script installer, it does not require administrative privileges to run:

                >  bash

    TopChem2: Julien PILMÉ