def get_tiltplane(self, sequence):
        '''
        Extract the main tilting plane basing on Z coordinate
        '''
        sequence = sorted(sequence, key=lambda x: self.virtual_atoms[ x ].z)
        in_plane = []
        for i in range(0, len(sequence)-4):
            if abs(self.virtual_atoms[ sequence[i] ].z - self.virtual_atoms[ sequence[i+1] ].z) < self.OCTAHEDRON_ATOMS_Z_DIFFERENCE and \
            abs(self.virtual_atoms[ sequence[i+1] ].z - self.virtual_atoms[ sequence[i+2] ].z) < self.OCTAHEDRON_ATOMS_Z_DIFFERENCE and \
            abs(self.virtual_atoms[ sequence[i+2] ].z - self.virtual_atoms[ sequence[i+3] ].z) < self.OCTAHEDRON_ATOMS_Z_DIFFERENCE:
                in_plane = [sequence[j] for j in range(i, i+4)]
        return in_plane
Extract the main tilting plane basing on Z coordinate