# Critic2

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 https://github.com/aoterodelaroza/critic2.git


or visit the github page.

## Features

• 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.

## Files

• 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.
• INSTALL: installation instructions. These are automatically generated by autoconf.
• 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.

## Citation

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.