BAND-STRUCTURE AND NONLINEAR OPTICAL SUSCEPTIBILITIES OF PROUSTITE (AG3ASS3)

Theoretical and experimental investigations are made of the band structure of proustite (Ag3AsS3). The calculation is performed using the tight-binding method. As scale factors in the corresponding secular equation the experimental results of VUV-reflection are used in the spectral region 2 to 30 eV. The contribution of different electronic states to the electronic bands are obtained. From the calculated band energy structure and infrared spectra the influence of the cluster vibrations on the nonlinear susceptibilities is estimated and the contribution of the electronic and ionic part to the electrooptical tensors is separated.