Concepts, Methods and Algorithms This document provide background information for DFF. Project and File System Force Field Force Field Types Atom Types Parameters Molecular Topology and Atomic Attributes Definition of Atom Types Typing Rules Extending Definitions Hyper-valence Atom Types Equivalent and Integrated Atom Types Training Set Fragments Training Set data Quantum Mechanics Data Parametrization General Procedure Automatic Parameters Fitting Methods Fit Charge and Valence Parameters Fit Lennard-Jones Parameters TEAMFF Database Force Fields of TEAMFF Combination of Force Fields of TEAMFF Extensibility of TEAMFF MFDFF Overview How it works Implementation Simulations