Electronic properties of a methane–water solution

Electronic properties of a methane–water solution were investigated by a sequential quantum mechanical/molecular dynamics approach. Upon hydration methane acquires an induced dipole moment of ∼0.5 ± 0.2 D. This is related to polarisation effects and to weak methane–water hydrogen bond interactions. From gas phase to solution, the first vertical excitation and ionisation energies of methane are red-shifted by 0.45 ± 0.25 and 0.87 ± 0.40 eV, respectively. We also report results for the dynamic polarisability of methane in water. In comparison with water, no difference was found for the average monomeric dipole moment of water molecules in close interaction with methane.