References -- 5 Application of Computational Chemistry for Contaminant Adsorption on the Components of Soil Surfaces -- 5.1 Introduction -- 5.2 Density Functional Theory (DFT) -- 5.2.1 Preliminaries -- 5.2.2 Bloch Function -- 5.2.2.1 Bypassing Periodicity: Cluster Models -- 5.2.3 K-point Sampling -- 5.2.4 Density of States (DOS) and Analysis of Orbitals -- 5.2.5 Self-Interaction Errors -- 5.2.6 The Problem of Electron Correlation -- 5.2.7 Forces, Hellmann-Feynman Theorem, and Geometry Optimization -- 5.3 Case Study: Adsorption of Munitions in Soils -- 5.3.1 Binding Energies -- 5.3.2 Cluster Models and Electrochemical Properties -- 5.3.3 Comparison of Cluster and Periodic Surface Models -- 5.3.4 Lewis Acidity and Environmental Fate -- 5.3.5 Environmental Transport -- 5.4 Looking to the Future -- 5.4.1 Breathing New Life into an Old Method: Density Functional Tight Binding -- 5.4.2 Artificial Intelligence and Machine Learning (AI/ML) -- 5.4.2.1 Machine Learning and Energetics -- 5.4.2.2 AI/ML and DFT -- 5.5 Conclusions -- References -- 6 Application of Computational Approaches to Analysis of Multistep Chemical Reactions of Energetic Materials: Hydrolysis of Hexahydro-1,3,5-Trinitro-1,3,5-Triazine (RDX) and Octahydro-1,3,5,7-Tetranitro-1,3,5,7-Tetrazocine (HMX) -- 6.1 Introduction -- 6.1.1 Short Survey of Experimental Data on RDX Hydrolysis -- 6.1.2 Short Survey of Experimental Data of HMX Hydrolysis -- 6.2 Computational Modeling of Hydrolysis of RDX -- 6.2.1 Conformational Analysis of RDX Structure -- 6.2.2 Mechanism of |