phosphate groups. Bridges between phosphate and solvent-exposed nucleobase atoms have also been identified. The 2 ′ -hydroxyl group, typical of the ribose ring, has been under special focus, with water molecules suggested to form bridges between the 2 ′ -OH and phosphate or base atoms. However, while early studies suggested the 2 ′ -OH group to be involved in long-lived water bridges, molecular dynamics simulations showed that there is no long lived hydrogen-bond between water and the 2 ′ -OH group, and that water molecules with long residence times (up to several hundreds of ps) are found instead next to the phosphate oxygen atoms, with long-lived water bridges between successive O R phosphate oxygen atoms.