File Structure

Potable files for pair-potential models may contain the following sections:






Each section may contain a number of configuration options. These have the general form:


or an equals sign may be used instead:


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.
  • [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].
  • [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:

  • [EAM-Density] is described here.
  • [EAM-Embed] is described here.