3.3. Harmonic Bond¶
3.3.1. Functional Form¶
The harmonic bond potential has the functional form:
\(E = {K_{ij}} \cdot \left( {{R_{ij}} - {R_{0,ij}}} \right)^{2}\)
The force-field parameters for this potential and units are given by:
| Equation Symbol | Parameter Definition | Units |
| \(K_{ij}\) | Bond coefficient for atoms [i,j] | energy/length^2 |
| \(R_{0,ij}\) | Equilibrium bond length for atoms [i,j] | length |
3.3.2. XML Schema¶
The XML schema for the harmonic bond potential has the following representation (design mode representation using Liquid XML Studio):
The relationship between the equation symbols and XML schema notations are given by:
| Parameter Definition | Equation Symbol | Schema Notation |
| Atom type of atom [i] | \(i\) | AT-1 |
| Atom type of atom [j] | \(j\) | AT-2 |
| Bond coefficient for atoms [i,j] | \(K_{ij}\) | K |
| Equilibrium bond length for atoms [i,j] | \(R_{0,ij}\) | R0 |
The general attributes (describing the entire data set) are given by:
| General Attributes | Cardinality | Value/Definition |
| style | Fixed | Harmonic |
| formula | Fixed | K*(R_R0)^2 |
| K-units | Required | Enumerations specified in schema |
| R0-units | Required | Enumerations specified in schema |
The specific attributes (attached to each set of parameters) are given by:
| Specific Attributes | Cardinality | Value/Definition |
| comment | Optional | Comment attached to parameter set |
| version | Optional | Version number of parameter set |
| reference | Optional | Reference attached to parameter set |
Note that an XML document will be rejected from being entered into the WebFF database if a required attribute is left unspecified.