FIRST-PRINCIPLES STUDY ON METAL-DOPED ICOSAHEDRAL B-12 SOLIDS

Theoretical exploration of a group of ''C-60-like'' B-12-based materia ls, A(x)B(12). With A=(Li and Ca) and x=1-4, is made by performing loc al-density approximation Gaussian basis calculations of the total ener gy, heats of formation, lattice constant, electronic structure, densit y of states, and bulk modulus of the putative compounds, using ab init io pseudopotentials. Lithium-doped materials are mostly demonstrated t o give sufficient heats of formation, whereas it is shown that all Ca- doped materials are unstable, including Li2CaB12. Results are presente d only for the stable and metastable LixB12 and compared with other cu rrent theoretical calculations on K3C60 The possibility of superconduc tivity is also discussed. The band-structure calculations reveal essen tially metallic behavior of LixB12. Important differences are found in the energy band structures, particularly in bands near the Fermi leve l, that would be reflected in superconductivity of these systems. Favo rable superconducting properties are expected for Li3B12, in the conte xt of sufficiently high N(E(F)) and obtained bulk modulus that is indi cative of strong electron-phonon coupling.