surface revealed that the water adsorption is relatively weak (physisorption). The energy barrier for water dissociation on Fe(100) is approximately 1.45 eV based on the climbing NEB transition state method. However, these results did not agree with the observation of Eder et al. which primarily might be due to the utilization of projector augmented wave method (PAW) potentials in the study. The PAW potentials offer a more accurate treatment of the core electronic states by keeping all electron wavefunctions and potentials, as opposed to ultrasoft pseudopotentials. The water dissociation barrier on the Fe(110) surface was found as 0.79 eV using the optPBE vdW functional, whereas the energy barrier of reaction *OH → *O + *H is observed to be 2.12 eV. The adsorption energies of water clusters (dimers to pentamers) on the Fe(100) surface showed moderate binding, with the binding energy ranging from -0.34 to -0.6 eV.