Quantum mechanical basis for Mulliken population analysis

Using an approach alternative to that of Mayer, this paper shows that a Hermitian operator can be found, such that, in a molecule atomic populations can be obtained as its expectation values. In this way, atomic charges can be computed within a quantum mechanical correct definition. When working within the LCAO MO framework, it is found that Mulliken populations appear as the appropriate expectation values of the charge operator.