The methodology developed by the author and presented in this monograph is aimed at evaluation of formation processes for complex, multi-component systems and is based on the understanding of spatial-energy parameter (P-parameter). Such a criterion is introduced when analyzing several physical and chemical regularities, including Lagrangian equations and consideration of the most important atomic characteristics. Specific application of such an approach to estimate the degree and direction of structural interactions, phase-formation processes, in numerous (over a thousand) systems, including molecular ones, is given. The monograph contains a lot of methodological, calculating and informative material to be used in practical material science in the process of theoretical studies and research of structural interactions in condensed and molecular systems.