Surface adsorbate vibrations explored by infrared spectroscopy and DFT cluster calculations at the anharmonic level: CO on Cu(100).

The vibrational properties of the CO/Cu(100) surface adsorbate system have been explored by infrared spectroscopy and DFT cluster calculations. We show that all four fundamental, FT(x,y), FR(x,y), FT(z) and ν(C-O), vibrational modes are very well reproduced with respect to experiments by the present calculations and they are at the highest level reported to date. Our work demonstrates that it is essential to include both anharmonicity and cluster relaxation when modeling the CO/Cu(100) system. The absence and presence of binary modes: 2 ×ν(C-O) and FT(z) + ν(C-O) in our experimental data are discussed as well