On the quest for a molecular vibration whose absolute intensity is described solely by fluctuations of atomic dipoles: Can we find it?

The conditions for a molecular vibration to be active in the infrared spectrum while its absolute intensity is described solely by fluctuations of atomic dipoles are presented. A quick recipe of features of such a system is presented, to guide the seek for it. If such a system can be found, it will then be proved that population analyses based solely on a point-charge approximation are unrealistic as they cannot properly describe this intensity, a real, measurable, unambiguous property.