Available online at http://www.idealibrary.com on doi:10.1006/spmi.2001.0995 Superlattices and Microstructures, Vol. 30, No. 2, 2001 Electronic structure of CuCl x Br 1-x , CuCl x I 1-x and CuBr x I 1-x alloys F. EL HAJ HASSAN † , A. ZAOUI ‡ Condensed Matter Group, International Center for Theoretical Physics, Strada Costiera 11-34014 Trieste, Italy (Received 13 June 2001) In this work, the electronic structure and disorder effects in copper halides alloys are stud- ied by means of the full potential linearized augmented plane wave (FLAPW) method. The calculated bowing parameter shows that the main contribution is due to the relaxation effects, though the charge transfer remains relatively significant, while the volume defor- mation contribution is negligible. The total bowing is found to be small in the three studied alloys. Results agree well with experimental and available theoretical works. c  2001 Academic Press Key words: bowing, FLAPW, copper halides alloys. 1. Introduction The copper halides are prototype materials for non-linear optical experiments [1]. Recently, they found renewed interest because of the possibility of producing microcrystals [2]. As promising candidates for pho- tosensitive and semiconducting materials, copper halides attract much attention. The copper halides CuCl, CuBr and CuI crystallize under ambient conditions in the zinc blende structure. A closer look at the structural properties of isovalent I–VII semiconductor alloys made possible by more recent measurements [3–7] reveals, however, that these alloys form a complete solid solution. Recently, Bouhafs and co-workers studied the band structures of CuCl 1−x Br [8], CuCl 1−x I x [9] and CuBr 1−x I x [10] alloys. Their works used tight-binding (TB) theory within the virtual crystal approximation (VCA). More recently, Sekkal et al. [11, 12] studied the miscibility of copper halides using a three-body potential. The virtual crystal approximation (VCA) treats an alloy as a perfectly periodic crystal with an average po- tential at each sublattice site, while the coherent potential approximation (CPA) retains the separate identities of atomsŠ sublattices but averages them over the environments of each site. The principal simplification of the VCA and the CPA lies in the association of the average alloy properties with those of ‘effective atoms’ on sites. These calculations predicted only trends of specific quantities not qualitatively or quantitatively accurate results. The purpose of this paper is to study the electronic structure and disorder effects in copper halides alloys, by using the full potential linearized augmented plane wave (FLAPW) method. To model the alloy, we use the approach developed by Zunger and co-workers [13, 14]. In this approach, the alloy is studied in an ordered structure (we use here a cubic supercell of eight atoms) designed to reproduce the most important pair correlation functions of a random (disorder) alloy and where the chemical and structural effects are † Present address: L. P. L. I., IUT mesures physiques, 08 rue Marconi, Technopole 2000, 57078 Metz, France. ‡ Corresponding author: E-mail: 0749–6036/01/080075 + 06 $35.00/0 c  2001 Academic Press