Car-Parrinello and path integral molecular dynamics study of the hydrogen bonds in 2-acetyl-1,8-dihydroxy-3,6-dimethylnaphthalene

► For the strong intramolecular hydrogen bond very large delocalization of bridging proton is noted, especially in the path integral simulation where quantum effects are taken into account. ► No tautomerism was found for this intramolecular hydrogen bond. ► Geometry optimization at the PBE1PBE/6-311++G(2d,2p) level demonstrate the existence of two tautomers on the potential energy surface.