Orthogonalized-Plane-Wave Theory of Metallic Binding

It is demonstrated that the orthogonalized-plane-wave (OPW) method yields binding energies, equilibrium lattice constants, and bulk moduli for metals (aluminum in particular) in as good agreement with experiment as do the cellular methods. The failure of other workers to achieve good agreement is due to the use of incorrect core eigenvalues; one must also be careful not to count certain interactions twice. There appear to be uncertainties in the exchange and correlation contributions to the energy much larger than the error in the calculated binding energy (for either OPW or cellular calculations). The probable effects of eliminating some of these uncertainties with a screened Hartree-Fock crystal calculation are discussed in an appendix.