calculate(self)

run a calculation. you have to be a little careful with code in here. Use the calculation_required function to tell if a calculation is required. It is assumed here that if you call this, you mean it.

calculation_required(self, atoms=None, quantities=None)

determines if a calculation is needed.

return True if a calculation is needed to get up to date data. return False if no calculation is needed.

quantities is here because of the ase interface.