Non-covalent interaction via the reduced density gradient: Independent atom model vs experimental multipolar electron densities

► The reduced density gradient (RDG) is used to study non-covalent interactions (NCIs). ► X-ray vs Independent Atom Model (IAM) charge density NCI pictures are contrasted. ► The two pictures generally reveal the presence of the same interactions. ► NCI information at the IAM level is much less detailed and chemically meaningful. ► Use of the simpler RDG-IAM approach to study NCI in complex systems is questioned.