Angles schema
=============
A full description of the overall Angles model.

Required Keys
-------------

The following properties are required for the Angles specification.
   +-------------------------------------------------------------------------------------------------+--------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------+
   | Key Name                                                                                        | Description                                                                                                              | Field Type                                                                       |
   +=================================================================================================+==========================================================================================================================+==================================================================================+
   | angles                                                                                          | Equilibrium angles. Default unit is degrees.                                                                             | array[number]                                                                    |
   +-------------------------------------------------------------------------------------------------+--------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------+
   | connectivity                                                                                    | Particle indices for each angle.                                                                                         | array[array]                                                                     |
   +-------------------------------------------------------------------------------------------------+--------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------+
   | form                                                                                            | Name or form of the potential. See cls.supported_potentials() for available potentials.                                  | string                                                                           |
   +-------------------------------------------------------------------------------------------------+--------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------+
   | params                                                                                          | Specific force field parameters model.                                                                                   | object                                                                           |
   +-------------------------------------------------------------------------------------------------+--------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------+

Optional Keys
-------------

The following keys are optional for the Angles specification.
   +-------------------------------------------------------------------------------------------------+--------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------+
   | Key Name                                                                                        | Description                                                                                                              | Field Type                                                                       |
   +=================================================================================================+==========================================================================================================================+==================================================================================+
   | angles_units                                                                                    | Equilibrium angle units.                                                                                                 | string                                                                           |
   +-------------------------------------------------------------------------------------------------+--------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------+