UFCalculator error when model has resolution 0 for an interaction

[henk789]

Problem description

When loading a model that has knot resolution 0 for an interaction, using UFCalculator results in an error message:

Traceback (most recent call last):
  File "/home/***/***/***/.conda/envs/uf3_env/lib/python3.8/concurrent/futures/process.py", line 239, in _process_worker
    r = call_item.fn(*call_item.args, **call_item.kwargs)
  File "/scratch/slurm_tmpdir/job_21050829/ipykernel_1790295/233011300.py", line 22, in eval
    p_f = np.append(p_f, geom.get_forces())
  File "/home/***/***/***/.conda/envs/uf3_env/lib/python3.8/site-packages/ase/atoms.py", line 788, in get_forces
    forces = self._calc.get_forces(self)
  File "/pfs/data5/home/***/***/***/ba/uf3/uf3/forcefield/calculator.py", line 215, in get_forces
    f_3b = self.forces_3b(atoms, supercell)
  File "/pfs/data5/home/***/***/***/ba/uf3/uf3/forcefield/calculator.py", line 288, in forces_3b
    val_l = spline(triangles, nus=np.array([1, 0, 0]))
  File "/home/***/***/***/.conda/envs/uf3_env/lib/python3.8/site-packages/ndsplines/ndsplines.py", line 220, in __call__
    self.compute_basis_coefficient_selector(x, nus)
  File "/home/***/***/***/.conda/envs/uf3_env/lib/python3.8/site-packages/ndsplines/ndsplines.py", line 172, in compute_basis_coefficient_selector
    impl.evaluate_spline(t, k, x[:,i], nu, extrapolate_flag, self.interval_workspace[i], self.basis_workspace[i],)
  File "ndsplines/_bspl.pyx", line 96, in ndsplines._bspl.evaluate_spline
ValueError: Buffer dtype mismatch, expected 'const double' but got 'long'

Solution

The issue arises due to the JSON parsing used when loading models. Since the seven knot positions are all 0, they are loaded as integers. However, the ndspline package requires double. Therefore, the issue can be avoided when converting integer knot positions to doubles.