A quantum-mechanical/molecular-mechanical calculation method for molecules or molecular aggregates adsorbed on noble metal surfaces

We propose a quantum-mechanical/molecular-mechanical method to calculate characteristics including energies and stable structures for molecules or molecular aggregates adsorbed onto noble metal surfaces. In this method, on the one hand, quantum-chemical calculations for the adsorbate with image charges, which appear in the metal due to the electrostatic influence of the adsorbate on the metal, are made; therefore, the inductive interaction between the adsorbate and the surface is included in the calculations. On the other hand, analytical atom–atom potential functions are used to represent the repulsive and dispersive interactions between the surface and the adsorbate. We show that our method is useful for investigating physisorption on noble metal surfaces.