[ase-users] Constraints issue in vasp calculator

[Protik Das]

Hi,

I am using ase in a python 3.6 environment to do some vasp calculations. I
am using plane constraint to fix all the atoms in z direction. I am getting
the following error before the calculation starts:

Traceback (most recent call last):
  File "isif.py", line 109, in <module>
    energ1 = interface.get_potential_energy()
  File
"/home/protik/anaconda3/envs/ase/lib/python3.6/site-packages/ase/atoms.py",
line 682, in get_potential_energy
    energy = self._calc.get_potential_energy(self)
  File
"/home/protik/anaconda3/envs/ase/lib/python3.6/site-packages/ase/calculators/vasp.py",
line 835, in get_potential_energy
    self.update(atoms)
  File
"/home/protik/anaconda3/envs/ase/lib/python3.6/site-packages/ase/calculators/vasp.py",
line 492, in update
    self.calculate(atoms)
  File
"/home/protik/anaconda3/envs/ase/lib/python3.6/site-packages/ase/calculators/vasp.py",
line 684, in calculate
    self.initialize(atoms)
  File
"/home/protik/anaconda3/envs/ase/lib/python3.6/site-packages/ase/calculators/vasp.py",
line 592, in initialize
    self.atoms_sorted = atoms[self.sort]
  File
"/home/protik/anaconda3/envs/ase/lib/python3.6/site-packages/ase/atoms.py",
line 949, in __getitem__
    con.index_shuffle(self, i)
  File
"/home/protik/anaconda3/envs/ase/lib/python3.6/site-packages/ase/constraints.py",
line 86, in index_shuffle
    if old == self.a:

I tried using the equal function from ase.calculators.calculator, but that
did not work. Any help regarding this?
-- 
Protik Das,
ECE Graduate Student,
LATTE (http://latte.ece.ucr.edu),
University of California, Riverside.
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