Lithium energy-band structure calculations using ab initio pseudopotentials

A recently suggested method for constructing ab initio pseudopotentials has been applied to Li and used to calculate the energies at high-symmetry points of the Brillouin zone for lithium metal. This potential is unique, local, and Hermitian and is much weaker than the Hartree-Fock potential. As a result of the weakness of the potential, the conduction-band orbitals are smooth in the core regions, and plane-wave expansions are found to converge rapidly. (There is no restriction that the conduction orbitals be made orthogonal to the core orbitals.) The lowest energy band has character similar to the band obtained from orthogonalized planes-wave calculations using the Seitz empirical potential.