Critic2 is a program for the analysis of quantum mechanical calculation results in molecules and periodic solids.

Alternatively, clone the git repository for the latest version of the code:

git clone

or visit the github page. This manual and the examples refer to the latest version only. If you find a bug in either the stable or development versions, chances are it is already fixed in the github repository.


  • Read and transform between file formats used in quantum chemistry and physics.

  • Read, analyze, and manipulate scalar fields such as the ELF or the electron density.

  • Perform topological analysis of real-space scalar fields, which includes the implementation of Bader’s atoms in molecules theory (QTAIM): critical point search, basin integration, basin plotting, etc.

  • Calculation of Bader’s delocalization indices in periodic solids.

  • Calculation and integration of new scalar fields using critic2’s powerful arithmetic expressions, useful in the development of quantum mechanical methods.

  • Critic2 implements other related techniques, such as non-covalent interaction plots (NCIplots) in molecules and solids or the calculation of scanning tunneling microscopy (STM) plots.

  • Crystallographic calculations: space group detection (via the spglib), unit cell transformation, powder diffraction and RDFs, structural comparison, molecule environment generation, and more.

  • Critic2 understands structures and scalar fields generated by many programs: WIEN2k, elk, PI, Quantum ESPRESSO, abinit, VASP, DFTB+, Gaussian, psi4, orca, siesta, cif, SHELX, and more.


  • README: some basic instructions for installing and using the program.
  • AUTHORS: the authors of the package.
  • LICENSE: a copy of the licence. Critic2 is distributed under the GNU/GPL license v3.
  • THANKS: acknowledgements to various people that contributed code or external libraries.
  • src/: source code. The critic2 binary is generated in here.
  • dat/: atomic density, cif database, and other data. These need to be accessible to critic2 at runtime (either by configuring with the prefix option or setting the CRITIC_HOME environment variable, see Installation.


The basic references for critic2 are:

Please cite these if you find this program useful. See the outputs and the manual for references pertaining particular keywords.

Critic2 is distributed under the GNU/GPL v3 license. The LICENSE file in the root of the distribution contains a copy of the license.