On the energy band gap correlation and effective charges of some ternary chalcopyrites and their mixed versions

We have been able to obtain for the first time a correlation of the lowest energy band gap with the average principal quantum number and molecular weight for the ternary chalcopyrites and their mixed versions which in turn helps in estimating the band gap, the latter being a key design parameter for various optoelectronic devices. The agreement of our results with the available experimental values and obtained by other approaches is quite encouraging. Finally we report our studies on the effective charges of the above compounds, following the quantum dielectric theory of Phillips and Van Vechten, which will be very much helpful for explaining the complex dielectric behaviour of these crystals.