8.11. Non-Bond Soft Potential¶
8.11.1. Functional Form¶
The non-bond Soft potential has the functional form:
\(E={{A}_{ij}}\left[ 1+\cos \left( \frac{\pi R}{{{R}_{c}}} \right) \right]\)
The force-field parameters for this potential and units are given by:
| Equation Symbol | Parameter Definition | Units |
| \(A_{ij}\) | Coefficient for atom [i] | energy/mol |
| \(R_{c}\) | Interatomic cut-off distance for atom [i] | length |
8.11.2. XML Schema¶
The XML schema for the non-bond Soft 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] | (implicit) | AT1 |
| Atom type of atom [j] | (implicit) | AT2 |
| Coefficient for atom [i] | \(A_{ij}\) | a_ij |
| Interatomic cut-off distance for atom [i] | \(R_{c}\) | r_c |
The general attributes (describing the entire data set) are given by:
| General Attributes | Cardinality | Value/Definition |
| style | Fixed | Soft |
| formula | Fixed | a_ij*[1+cos(pi*r/r_c)] |
| a_ij-units | Required | Enumerations specified in schema |
| r_c-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.