message: Added derivative interface.
diff: @@ -166,6 +166,25 @@ class SOAP(Descriptor):
  self._average = average
  self.crossover = crossover
  + def derivatives(self, system, positions=None, include=None, exclude=None, method="numerical"):
  + """Return the SOAP output for the given systems and given positions.
  +
  + Args:
  + system (:class:`ase.Atoms` or list of :class:`ase.Atoms`): One or
  + many atomic structures.
  + positions (list): Positions where to calculate SOAP. Can be
  + provided as cartesian positions or atomic indices. If no
  + positions are defined, the SOAP output will be created for all
  + atoms in the system. When calculating SOAP for multiple
  + systems, provide the positions as a list for each system.
  + n_jobs (int): Number of parallel jobs to instantiate. Parallellizes
  + the calculation across samples. Defaults to serial calculation
  + with n_jobs=1.
  + verbose(bool): Controls whether to print the progress of each job
  + into to the console.
  + """
  + pass
  +
  def create(self, system, positions=None, n_jobs=1, verbose=False):
  """Return the SOAP output for the given systems and given positions.
  