A THEORETICAL INVESTIGATION OF THE ELECTRONIC-STRUCTURE, HYPERFINE PROPERTIES AND BINDING-ENERGIES OF MUONIUM CENTERS IN CUPROUS CHLORIDE

A series of self-consistent local-spin-density molecular-cluster calculations has been performed to investigate the electronic structure, the hyperfine (hf) properties and binding energies of muonium centres in curprous chloride. Spin-polarization was taken into account on a finite, stoichiometric cluster including Cu7Cl7 and an interstitial muonium (MU) atom. Different Mu positions along the direction 〈111〉 of the CuCl zinc blende structure between the two inequivalent tetrahedral interstitial sites (hereafter TCu and TCl) were investigated. Our results indicate a localization of Mu close to the TCu site, shifted about 0.5 Å toward the apical Cu atom of the employed cluster. Such a fact nicely agrees with experimental findings and it has been discussed and rationalized on the basis of the different bonding interaction between MU and the nearest neighbours. In the light of our theoretical outcomes, the single-electron model proposed by Cox and Symons for the reduction of the Fermi cont...