Overview of Forcefields

What is a forcefield? And what do all these terms, parameters, etc. actually mean? Unfortunately while there are many papers on forcefields and descriptions of what a forcefield is, many of them are quite specific and limited to the context at hand. The words used to describe forcefields, the terms in a forcefield, and how a forcefield is used – the jargon – is not consistent, particularly between subfields, and is very confusing.

While this document can’t solve all of these problems, it will lay out a general and simple description of forcefields and define the terminology used in SEAMM. It will also try to note some of the other terminology used by other groups and subfields. Hopefully this will help you more fully understand forcefield and be able to read the rest of the documentation about forcefields in SEAMM without being confused by the concepts and terminology.

We’ll use a specific example – OPLS – to illustrate a forcefield. OPLS is one of the earlier forcefields, so the description in the paper is reasonably complete. If you look at later papers, they tend to assume that you know the jargon that was introduced by various papers since the field was invented, which is a bit awkard if you don’t know the field, or if you come from a different field with different jargon!

• Functional Form
• Parameters
• Atom Types
• Types of Forcefields