ORBKIT is a parallel Python program package for post-processing wave function data from output files of quantum chemical programs.

ORBKIT:Copyright (C) 2017, Gunter Hermann, Vincent Pohl, and Axel Schild.

The computational capabilities of ORBKIT range from grid-based quantities, e.g., molecular orbitals or electron density, to non grid-based quantities for instance Mulliken population charges or analytical overlap integrals between molecular orbitals. There are several options and features to control the respective calculations like grid types and parameters. The required data can be extracted from MOLPRO (Molden File Format), TURBOMOLE (AOMix file format), GAMESS-US, PROAIMS/AIMPAC (wfn/wfx file format), and Gaussian (.log File and Formatted Checkpoint File) output files. Futhermore, an interface to cclib, a parser for quantum chemical logfiles, is provided. A complete list of all input and output formats as well as quantities and features of ORBKIT is given in General Aspects.

This documentation should serve as an overview of how to operate ORBKIT as a standalone program and how to use it in your own Python programs. The latter is facilitated by its modular design. For a quick introduction to ORBKIT, see the Quick Start Guide or stick to the example files in the ORBKIT program packet. Tutorials for the calculation of grid-based and non grid-based quantities are given in section Grid-Based Calculation and Non Grid-Based Calculation. Supplementary, a detailed description of the existing options, main variables, and functions is given in ORBKIT References. Finally, some additional applications of ORBKIT are presented in Advanced Tutorials.

NEW: detCI@ORBKIT extends ORBKIT’s functionality to multi-determinantal wave functions.


The source code and multiple example files of ORBKIT can be freely downloaded from the web page


For installation instructions, please check Installation Instructions.


If you use ORBKIT in your work, please cite it as follows:

Gunter Hermann, Vincent Pohl, Jean Christophe Tremblay, Beate Paulus, Hans-Christian Hege, and Axel Schild, “ORBKIT: A Modular Python Toolbox for Cross-Platform Postprocessing of Quantum Chemical Wavefunction Data”, J. Comput. Chem. 2016, DOI: 10.1002/jcc.24358.


The paper is also freely available on arXiv.

BibTex (orbkit.bib):

@article {orbkit,
  author = {Hermann, Gunter and Pohl, Vincent and Tremblay, Jean Christophe and Paulus, Beate and Hege, Hans-Christian and Schild, Axel},
  title = {ORBKIT: A modular python toolbox for cross-platform postprocessing of quantum chemical wavefunction data},
  journal = {J. Comput. Chem.},
  journalfull = {Journal of Computational Chemistry},
  volume = {37},
  number = {16},
  issn = {1096-987X},
  url = {http://dx.doi.org/10.1002/jcc.24358},
  doi = {10.1002/jcc.24358},
  pages = {1511--1520},
  keywords = {quantum chemical calculation, electronic structure, molecular visualization, electron density, grid representation of one-electron quantities, molecular orbital ordering},
  year = {2016}


The ORBKIT support team, Axel, Gunter, and Vincent, welcomes every new user and will be available to answer your questions. For any change requests, do not hesitate to contact the ORBKIT support team via


Indices and tables