In contrast, neutron scattering measurements  have found a soft phonon mode perpendicular to the chain (b-axis direction). In addition, X-ray diffraction measurements  found a large contraction of the b-axis lattice parameter at .Neutron scattering measurements under pressure  showed a pronounced decrease of the b-axis lattice parameter.
Chen et al. observed diffuse scattering below 100 K with electron diffraction measurements . They proposed a twisting mode of the CuO2 ribbons to explain their results.