C-H and C-C distance-energy curve differ between Rebo2 and Rebo2Scr

[threich]

The distance-energy curves for C-H and H-H dimers are not identical when using Rebo2 and Rebo2Scr although these bonds should be unaffected by the screening of C-C bonds. It seems that the used cutoff function is not identical (as the difference occurs only in this range).

from ase import Atoms
from atomistica import Rebo2, Rebo2Scr
import numpy as np
import matplotlib.pyplot as plt

vac = 4
dist_min = 0.6
dist_max = 1.85

a = Atoms('CH', positions=[[0, 0, 0], [dist_min, 0, 0]])
a.center(vacuum=vac)
distances = np.linspace(dist_min, dist_max, 1000)

for potential in [Rebo2(), Rebo2Scr()]:
    a.set_calculator(potential)
    energies = []
    forces = []
    for dist in distances:
        a[1].position[0] = dist + vac
        energies += [a.get_potential_energy()]
    plt.plot(distances, energies)
plt.show()

results in (after adding labels)