Compute and set the cluster of atoms as a Molecule object. The siteato
        coordinates are translated such that the absorbing atom(aka central
        atom) is at the origin.

        Returns:
            Molecule

def _set_cluster(self):
        """
        Compute and set the cluster of atoms as a Molecule object. The siteato
        coordinates are translated such that the absorbing atom(aka central
        atom) is at the origin.

        Returns:
            Molecule
        """
        center = self.struct[self.center_index].coords
        sphere = self.struct.get_neighbors(self.struct[self.center_index], self.radius)

        symbols = [self.absorbing_atom]
        coords = [[0, 0, 0]]
        for i, site_dist in enumerate(sphere):
            site_symbol = re.sub(r"[^aA-zZ]+", "", site_dist[0].species_string)
            symbols.append(site_symbol)
            coords.append(site_dist[0].coords - center)
        return Molecule(symbols, coords)