A general procedure to obtain quantum mechanical charge and bond order molecular parameters

In an approach alternative to that of Mayer, a Hermitian operator is defined within the LCAO MO framework, which allows to obtain molecular charges and bond orders as expectation values of the first and second-order densities respectively. Such expectation values result to be nothing else than Mulliken's atom and bond populations. Thus, Mulliken populations appear to be non arbitrary condensed electron density partitions, obtained according to quantum mechanical usual procedures for molecular one and two electron observables. The theoretical simplicity of the outlined procedure can be easily extended in order to obtain the expectation values for higher-order electronic chemical bonds.