## natural population analysis (NPA)

https://doi.org/10.1351/goldbook.NT07080
The analysis of the @E01986@ distribution in a molecular system based on the orthonormal natural atomic orbitals. Natural populations, $$n_{i}\left(\text{A}\right)$$ are the occupancies of the natural atomic orbitals. These rigorously satisfy the @PT07089@: $$0 < n_{i}\left(\text{A}\right) < 2$$. The population of an atom $$n\left(\text{A}\right)$$ is the sum of natural populations $$n\left(\text{A}\right)=\sum _{\begin{array}{c} \text{A} \end{array}}n_{i}\left(\text{A}\right)$$. A distinguished feature of the NPA method is that it largely resolves the @BT06999@ dependence problem encountered in the Mulliken population analysis method.
Source:
PAC, 1999, 71, 1919. (Glossary of terms used in theoretical organic chemistry) on page 1954 [Terms] [Paper]