Linear-muffin-tin-orbital (LMTO) supercell and LMTO recursion calculations for the electronic structure of metallic glasses:Ca7Al3

The electronic structure of an 800-atom realistic model of a ${\mathrm{Ca}}_7$ ${\mathrm{Al}}_3$ glass is calculated with use of the tight-binding linear muffin-tin-orbitals (TB LMTO) scheme in conjunction with the recursion method. Results are compared with those obtained in a self-consistent standard LMTO calculation for 60-atom supercells of this glass. The total and partial densities of states (DOS’s) obtained in the two calculations show quantitative agreement and the results at the Fermi level agree with the experimentally available information. The recursion results for the 800-atom model show less structure, but retain all the essential features in the DOS obtained via the supercell calculation, indicating that a tight-binding description of (s,p)-bonded metallic systems is indeed possible. Minor differences in the DOS’s are believed to be primarily due to the difference between the standard LMTO Hamiltonian and the Hamiltonian used in the recursion calculation, the latter being less accurate than the former at energies away from the reference energies $E_{\nu }$’s. Computational efforts needed for the supercell (k-space) and the recursion (real-space) calculations are compared.