  Nanosprings have been object of intense investigations in recent years. They
can be classified as normal or binormal depending on the geometry of their
cross-section. Normal amorphous nanosprings have not been observed
experimentally up to now, and only recently the synthesis of a crystalline ZnO
normal nanohelix has been reported. We discuss the shape of the catalyst in
terms of the cross-sectional shape of the nanospring, and show that, within the
vapor-liquid-solid model, the growth of amorphous normal nanospring is not
energetically favoured.
