11.2. 4Site-Rigid Water Model¶
11.2.1. Functional Form¶
The 4Site-Rigid water model has the functional form:
\(E={{E}_{q}}+{{E}_{LJ}}\)
The force-field parameters for this potential and units are given by:
| Equation Symbol | Parameter Definition | Units |
| \(E_{q}\) | Charge potential energy | energy |
| \(E_{LJ}\) | Lennard-Jones potential energy | energy |
11.2.2. XML Schema¶
The XML schema for the 4Site-Rigid water model has the following representation (design mode representation using Liquid XML Studio):
The general sub-elements (the actual data set) are given by:
| Parameter Definition | Schema Notation |
| Distance between O and H | R_OH |
| Distance between O and M | R_OM |
| Angle between HOH | Theta_HOH |
| Lennard-Jones parameter | A |
| Lennard-Jones parameter | B |
| Charge of M | q_M |
| Charge of H | q_H |
| sigma | |
| epsilon |
The general attributes (describing the entire data set) are given by:
| General Attributes | Cardinality | Value/Definition |
| name | Required | The name |
| formula | Fixed | E=E_q+E_LJ |
| version | Optional | Version number of parameter set |
| comment | Optional | Comment attached to data set |
| A-units | Required | Enumerations specified in schema |
| B-units | Required | Enumerations specified in schema |
| R-units | Required | Enumerations specified in schema |
| Theta_HOH-units | Required | Enumerations specified in schema |
| sigma-units | Required | Enumerations specified in schema |
| epsilon-units | Required | Enumerations specified in schema |
Note that an XML document will be rejected from being entered into the WebFF database if a required attribute is left unspecified.