from msspec.calculator import MSSPEC
from ase  import Atoms
import numpy as np

symbol = 'Ni'            # The kind of atom for the chain
a = 3.499 * np.sqrt(2)/2 # The distance bewteen 2 atoms
                         # in [101] direction

chain = Atoms(symbol)
data = None
for i in range(1,5):
    atom = Atoms(symbol, [[0,0,i*a]])
    atom.rotate('y', 45)
    chain += atom

    calc = MSSPEC(spectroscopy='PED', algorithm='inversion')
    calc.calculation_parameters.scattering_order = 1

    chain.emitter = 0
    calc.set_atoms(chain)

    data = calc.get_theta_scan(level='3s', theta=np.arange(0,80,0.5), data=data)
    data[-1].views[0].set_plot_options(ylim=[0,0.045])
data.view()