Theoretical Study on the Polarizabilities of Molecules in Solution by the Quantum Mechanical/Molecular Mechanical Approach: Comparison with the Polarizable Continuum Model

We compute the static polarizabilities of formaldehyde and ethylene in water solution by means of the QM/MM simulations and the polarizable continuum model for the purpose to examine the dependence of the polarizability on the method to include solvent effects. It is found that the polarizability of formaldehyde as well as ethylene is hardly changed by the solvent modeled by QM/MM approach. The results are reasonably consistent with suggestions given by other theoretical investigations which revealed that polarizabilities of a monomer in the linear hydrogen bonded chain is not increased by the hydrogen bondings. In contrast to the QM/MM method, it turns out that the polarizabilities are clearly enhanced for the solutes embedded in the dielectric continuums though both methods indicate that the σ electrons dominantly contribute to the polarizability.