Extension of the muffin-tin Green's-function theory of defects: Application to defects in aluminum

The single-site muffin-tin Green's-function method for studying the electronic structure of neutral defects is extended to account explicitly for charge neutrality. The extension, which requires no additional computational effort, produces a charge density in the region of an Al vacancy which compares favorably with results of Chakraborty and Siegel. The extension is also compared with results by Deutz, Dederichs, and Zeller (DDZ) for substitutional Co, Ni, and Cu in Al. Owing to cancellation of small errors, the position of the $d$ resonance peak $E_d$ for Ni in Al is identical to that of DDZ. For Co and Cu in Al, the present value of $E_d$ is somewhat closer to the experimental value than are those of DDZ, although sizable discrepancies remain.