https://doi.org/10.1351/goldbook.E01986
If is the probability of finding an electron in the volume element at the point of a molecular entity with coordinates , then is the electron density at this point. For many purposes (e.g. X-ray scattering, forces on atoms) the system behaves exactly as if the electrons were spread out into a continuously distributed charge. The term has frequently been wrongly applied to negative charge population.
See also: charge density