The textbook "Obtaining and Researching Energetic Spectra and Optical Properties" offers a comprehensive analysis of the principles for generating new complex semiconductor compounds. It addresses the theoretical foundations used to calculate the band structures of ternary compounds such as TlInSe2, TlGaTe2, and InGaSe2. The work demonstrates that the valence bands of these compounds can be divided into three subgroups, with the upper group associated with an origin in p-states. Additionally, the analysis of the wave functions of the valence states is conducted to understand the properties of the semiconductors. The results are compared with existing theoretical and experimental data, leading to a satisfactory agreement. This book is aimed at professionals and students engaged in semiconductor physics and materials science.