Variational Methods in Statistical Thermodynamics - A Pedagogical Introduction.- Square-Gradient Models for Inhomogeneous Many-body Systems.- Classical Density Functional Theory for Molecular Systems.- Classical Density Functional Theory of Polymeric Fluids and Ionic Liquids.- Variational Perturbation Theory for Electrolyte Solutions.- Self-Consistent-Field Theory of Inhomogeneous Polymeric Systems.- Variational Methods for Biomolecular Modeling.-...