def _project_eigenvectors(self):
        """Eigenvectors are projected along Cartesian direction"""

        self._p_eigenvectors = []
        for vecs_q in self._eigenvectors:
            p_vecs_q = []
            for vecs in vecs_q.T:
                p_vecs_q.append(np.dot(vecs.reshape(-1, 3),
                                       self._projection_direction))
            self._p_eigenvectors.append(np.transpose(p_vecs_q))
        self._p_eigenvectors = np.array(self._p_eigenvectors)
Eigenvectors are projected along Cartesian direction