Vibrational properties of hydrogen atom adsorbed on Cu(111) and on Ir(111) surfaces

We investigate the quantum mechanical behavior, in particular, the vibrational properties, of H atoms adsorbed on metal surfaces. We carry out density functional theory–based calculations of the relevant potential energy curves (PECs) for the hydrogen on Cu(111) and Ir(111) systems and construct the adiabatic three-dimensional potential energy surfaces (PESs) based on the obtained PECs. The wave functions and the corresponding energies for the hydrogen motion on the PESs are calculated within the framework of the variation method. The results show that the H atom is adsorbed at the threehold hollow site of Cu(111) and it is strongly localized. On the other hand, on the Ir(111), the H atom is adsorbed at the top site and it exhibits delocalized features. Furthermore, our calculated energies for vibrationally excited hydrogen and deuterium adsorbed on Cu(111) and Ir(111) agree well with the corresponding recently observed high-resolution electron energy-loss spectroscopy loss peaks.