The water dimer II: Theoretical investigations

[Display omitted] •Detailed structure of the water hydrogen bond.•Universal water potential model.•Hydrogen bond tunneling dynamics.•12 dimensional VRT dynamics. As the archetype of aqueous hydrogen bonding, the water dimer has been extensively studied by both theory and experiment for nearly seven decades. In this article, we present a detailed chronological review of the theoretical advances made using electronic structure methods to address the structure, hydrogen bonding and vibrational spectroscopy of the water dimer, as well as the role of its potential energy surface in the development of classical force fields to describe intermolecular interactions in clusters and the condensed phases of water.