Technical Documentation
The Worm Model: Introduction

The Worm model is that of a continuous and unbranched chain. Each link in the chain consists of one atom which is connected to no more than two other. The ends of the chain may be joined to form a closed circle.

The force field consists of four terms: Bonds, Angles, Torsions and SoftSphereX. Bonds are always present. The Torsions term can be added only if Angles are also added.

A chain may be homogeneous: every link in the chain is made up of the same kind of atom. Or, the chain may be heterogeneous: the atoms may be of different types.

Modules are located within the Yup package at Yup/Models/Worm/. The FFA and Analyzer modules are designed for public use while the const module is not.

Module

Summary

const

Constants for the Worm modules: constructor functions and labels for the force terms; the location of the parameter library and a table containing legal prefixes, atom inclusion types, atom exclusion types and atomic masses.

FFA

Force Field Assembler Class and Function to create and manipulate worm models.

Analyzer

Functions to analyze Worm models

The const module defines the parameter library as Yup/Data/Worm/ (within the Yup package). However, the user can create and use a different library. In order to do this, first create a text file called source-of-constants in a previously empty directory. See FPF for the format of this document or copy it from the standard parameter library. Do not change the number of, or the names of, the inclusion and exclusion atom types. You can only modify existing interaction types (change the force field parameters), add new interaction types, or remove existing interaction types. (An interaction type is a combination of atom types, for example, a pair of atom types form a Bonds interaction type. It is necessary to define interaction types for all combinations that can occur in a model. At the same time, it is desirable to omit interaction types for illogical combinations, e.g., for two atom types that cannot form a bond.) When source-of-constants is ready, run the program Yup.fpf to convert it to a number of database files. Pass the path (to the enclosing directory) to the constructor function Worm().

The force field assembler is subclassed from the template Chains in Yup.Tools.Chains The force field assembler also make use of the functions in the LinSeq module which can also be found in Yup.Tools.


Force Field Assembly

Analysis

Development
FFA
HookeFFA
NonbondXFFA PDBPartMap Chains
Worm
Environment


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