A first principles theoretical study of the hydration structure and dynamics of an excess proton in water clusters of varying size and temperature

► A theoretical study of protonated water clusters is carried for varying cluster size and temperature. ► The structures of H+(H2O)n are found out through quantum chemical calculations for n = 5, 9, 17 and 21. ► The finite temperature behavior of the clusters is studied through ab initio dynamical simulations. ► The spectral features of OH modes and their dependence on hydrogen bonding states of water are discussed. ► The mechanism and kinetics of proton transfer processes in these clusters are also investigated.