Returns the grid for a particular axis.

        Args:
            ind (int): Axis index.

def get_axis_grid(self, ind):
        """
        Returns the grid for a particular axis.

        Args:
            ind (int): Axis index.
        """
        ng = self.dim
        num_pts = ng[ind]
        lengths = self.structure.lattice.abc
        return [i / num_pts * lengths[ind] for i in range(num_pts)]