Compute the energy for a single site in the structure
        
        Args:
            site_index (int): Index of site
        ReturnS:
            (float) - Energy of that site

def get_site_energy(self, site_index):
        """Compute the energy for a single site in the structure
        
        Args:
            site_index (int): Index of site
        ReturnS:
            (float) - Energy of that site"""
        if self._charged:
            warn('Per atom energies for charged structures not supported in EwaldSummation')
        return np.sum(self._recip[:,site_index]) + np.sum(self._real[:,site_index]) \
            + self._point[site_index]