File Structure¶
Potable files for pair-potential models may contain the following sections:
[Tabulation]
...
[Pair]
...
[Potential-Form]
...
[Table-Form:NAME]
...
[Species]
...
Each section may contain a number of configuration options. These have the general form:
ITEM : VALUE
or an equals sign may be used instead:
ITEM = VALUE
Where ITEM
identifies the configuration option’s name and VALUE
its value.
Lines maybe commented out using #
and line continuation is supported according to identation (see here for more details).
Each section of the file has a specific purpose and not all sections will be required in all cases:
- [Tabulation] section
- describes how the file should be converted into a table file by the potable command. Contains information such as cutoff, output table format and cutoff.
- [Pair] section
- this is where pair interactions are defined by parametrising a potential-form.
- [Potential-Form] section
- this section allows custom potential-forms to be defined. This may be required when you can’t find an appropriate function from those supplied with
atsim.potentials
. However in many cases this won’t be necessary and this section needn’t appear in your model definition.
- this section allows custom potential-forms to be defined. This may be required when you can’t find an appropriate function from those supplied with
- [Table-Form] section
- Multiple
[Table-Form]
sections may be specified. These allow potential-forms to be defined from tables of x,y points. These tabulated forms can be used in the same way as potnetials defined in[Potential-Form]
.
- Multiple
[Species]
- this is used to provide meta-data about the species being tabulated. In most cases this section can be omitted (as very little species data is used during pair-tabulation). It is however, sometimes useful to include atomic charges etc, here so that the input file represents a complete description of a given potential model.
For completeness the [EAM-Embed]
and [EAM-Density]
sections are mentioned here. These are not required for pair potential models but are used in many body models: