ASE/FHI-aims compatibility

FHI-aims calculator requires a separate calculator object to be assigned for each Atoms object. Otherwise references are created and calculations do not proceed after the first DFT calculation. 

Line 866 - added a deepcopy to create new calculator objects

This change restores intended functionality. Since Catlearn does not stop until it arrives at a result, this prevents other users from burning their computational time (and diskspace with growing .traj file!), when using an ASE/FHI-aims/Catlearn setup

catlearn/optimize/mlneb.py

@@ -14,6 +14,7 @@
 from ase.calculators.calculator import Calculator, all_changes
 from ase.atoms import Atoms
 from catlearn import __version__
+import copy
 
 
 class MLNEB(object):
@@ -862,7 +863,7 @@ def get_energy_catlearn(self, x=None):
 
  self.ase_ini.set_calculator(None)
  self.ase_ini = Atoms(self.ase_ini, positions=pos_ase,
- calculator=self.ase_calc)
+ calculator=copy.deepcopy(self.ase_calc))
  energy = self.ase_ini.get_potential_energy(force_consistent=self.fc)
  return energy