The orthogonalized-plane-wave (OPW) series convergence up to 900 OPW's is illustrated for equal-core-size compounds C, Si, ZnSe, and CdTe, for large-cation-small-anion compounds ZnO, AIN, and Zns, and for large-anion-small-cation compounds BAs, BeTe, and ZnTe. Herman's overlapping-free-atom-potential model is used primarily, although self-consistent OPW convergence results are given for BAs. It is found that the first row of the Periodic Table is exceedingly difficult to handle with the OPW formalism. The primary factors involved in OPW convergence are found to be the presence or absence of core functions in the OPW's (which was realized long ago) and the relative core sizes of anion and cation. Criteria are given for estimating the OPW convergence behavior of compounds.

• Received 9 October 1969

DOI:https://doi.org/10.1103/PhysRevB.1.4692