introduction.md

1. Introduction

In this user guide, you will learn:

• DMFF Installation
• Basic usage of DMFF, including how to compute energy, forces and parametric gradients
• How to write XML format force field
• Theoretical background of various force field models

The first thing you should know is that DMFF is not an actual force field model (such as OPLS or AMBER), but a differentiable implementation of various force field (or "potential") functional forms. It contains following modules:

• ADMP module: Automatic Differentiable Multipolar Polarizable potential (MPID like potentials)
• Classical module: implements classical force fields (OPLS or GAFF like potentials)
• SGNN module: implements subgragh neural network model for intramolecular interactions

Each module implements a particular form of force field, which takes a unique set of input parameters, usually provided in a XML file. With DMFF, one can easily compute the energy as well as energy gradients including: forces, virial tensors, and gradients with respect to force field parameters etc.