The JANPA project homepage

Program features in brief

JANPA is a freeware program package for performing Natural Population Analysis - a method for partial atomic charges calculation and Natural Atomic Orbital creation.

Our independent implementation of the Natural Population Analysis method (see J.Chem.Phys.83, 735) produces the same results as the original NBO program, but is free, open-source, cross-platform and all details of its implementation are described in a published paper.

NEW!A new version 2.00 of the janpa program is available. This version features implementation of a newly developed localized property-optimized orbitals (LPOs) and 'the Chemist's LPOs' (CLPOs) orbital localization methods thus extending the application range significantly

Note that by using JAPNA you accept the following License

The JANPA package consists of three programs:

  • Janpa - takes MOLDEN-fompatible file as an input and performs NAO/NPA and Wiberg bond indices analysis
  • molden2molden - converts MOLDEN-semi-compatible files produced by particular quantum chemistry packages into MOLDEN-compatible files (in an 'extended' MOLDEN format)
  • nwchem2molden - prepares MOLDEN-compatible files from the results of electronic structure calculation done with NwChem

JANPA can be used to analyse electronic structures produced by PSI4, NwChem, ORCA, Gaussian, GAMESS and other popular quantum chemistry packages (see Documentation for details)

Quick facts about Janpa

  • JANPA 2.00 (12-04-2018) (excluding Jama library) contains 40 files with 8005 lines of code and 6259 lines of comments.
  • JANPA 1.04_r2 (20-07-2016) JANPA (excluding Jama library) contains 31 files with 6061 lines of code and 4947 lines of comments.
  • JANPA 1.03.rc2 (31-10-2014) JANPA (excluding Jama library) contains 29 files with 5837 lines of code and 4861 lines of comments.
  • JANPA 1.02 (07-09-2014) (excluding Jama library distributed with Janpa) consists of 27 source files with 5230 lines of code and 4378 lines of comments
  • (statistics obtained with CLOC tool)
  • JANPA's code has no relation to an original NBO program (developed by University of WisconsinЦMadison-based team) and represents a completely independent implementation of NAO/NPA algorithms.

Getting started with JANPA

Keep updated

Subscribe to our mailing list for the latest news:

Enter your email address:

Citation information

If any results and/or source codes obtained with/from JANPA are published, or for other purpose, please use the following citation:

Some recent publications in which JANPA was used:


Contacts / How to help the project

For any comments or suggestions concerning the project you can contact developers at janpa that typical sympol in e-mail addresses