Stability and Nonadiabatic Effects of the Endohedral Clusters X@Al12 (X = B, C, N, Al, Si, P) with 39, 40, and 41 Valence Electrons

Metallic nanoclusters, with one electron or hole difference from closed shell, might end up in a degenerate state undergoing a Jahn-Teller distortion as a result of nonadiabatic effects, which are a manifestation of the electron-vibron coupling. Here, we report a theoretical study on the stability and nonadiabaticity of the neutral and charged endohedral clusters X@Al-12 (X = B, C, N, Al, Si, P) around icosahedral symmetry, for 39, 40, and 41 valence electrons. The nonadiabatic effects are evaluated through the Jahn-Teller gain for the distorted cluster and their effect Oil the calculated electronic density of states is analyzed. For the 40 electron valence systems, we present the full vibrational spectra. Our results are discussed within the framework of the superatom model, and show that not all systems are well described by the spherical jellium model and that nonadiabaticity is better represented by ellipsoidal models. We present a detail discussion of the Al-13(-1) electron detachment process and show how, through a comparison with available experimental photoelectron spectroscopy data, the nonadiabaticity can be estimated.