Lithium atom can be doped at the center of a germanium cage: The stable icosahedral Ge12Li− cluster and derivatives

Structure and stability of the Ge12Mx clusters with M = Li, Na, Be, Mg, B, Al, and x from −1 to +1, each containing 50 valence electrons are investigated using DFT calculations. The global minima turn to be the high symmetry icosahedral structures, with large HOMO–LUMO gaps and high detachment or ionization energies. In particular, Li is found for the first time to be located at the center of an icosahedron Ge12Li−. The high thermodynamic stability of the icosahedra arises from a combination of their closed crystal field shells, spherical aromaticity and electrostatic attraction force.