[en] Intermolecular and intramolecular weak interactions have been described extensively with dispersion corrections from an energetics perspective. However, insights gained from a wave function view are to a lesser extent. Using two approximate density functionals B3LYP and M06-2X, together with D3BJ, DCP, and NL dispersion corrections, we have systematically explored and established the quantum topology phase diagram (QTPD) of 58 monosaccharide isomers within the framework of quantum theory of atoms in molecules for the first time. We find that merely NL dispersion corrections have an impact on the QTPD where those dubious points are further benchmarked and ruled out by the CCSD method. In addition, we use the Poincaré–Hopf relation rather than the Euclidean geometry to quantify the dimensionality of a molecule. This quantum topological definition of geometry reveals that the most energetically stable monosaccharide C₆H₁₂O₆ conformers are quantified as two-dimensional. Graphical abstract: < Image>.