The Natorbs program was created in response to the demand in the course of research on the electronic structure of open-shell systems as a useful tool for the analysis of the electronic structure. 

As input, the program takes the calculation results obtained by the Hartree-Fock (HF) or density functional theory (DFT) method, i.e. molecular (canonical) orbitals, and performs the analysis of these data by calculating natural, natural spin or natural orbitals for chemical valence. 

What distinguishes this program, is the implementation of the above-mentioned methods independently of the specific package used for quantum-chemical calculations. 

The input data is entered using well-defined interfaces (Molden format or CCLIB library: https://cclib.github.io/), making it possible to work with virtually any quantum-chemical program. 

The program is hereby made available free of charge on the basis of the so-called BSD three-clause license.
Copyright 2021 Jagiellonian University, PhD Mariusz Radoń.

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