Nanotubes and nanowires are promising materials since they show novel physical-chemical properties and
potential applications in many new technologies. SnO2 is a semiconductor of n-type with a band gap of 3.6 eV at 300K.
Nanotubes of tin oxide have been widely studied. SnO2 nanotubes are known for different applications, e.g., gas sensors,
transistors, and solar cells. This semiconductor has been obtained as a nanomaterial with a large number of morphologies
and properties. We have built the geometries for the [(SnO2)n]m nanotubes using the structure of the rutile crystal
lattice, where n represents the number of SnO2 units for nanotube layer (n=6,...,30), and m stands for the layer number.
The semi-empirical MNDO, DFT-B3LYP-Huzinaga and HF-Huzinaga were used in order to optimize the dSn-Sn, dO-O, dSn-
O interatomic distances. The minimum energies (eV) corresponding to the structures are given as well as the gap (HOMOLUMO)
for the variation of three different distances for each unit number of [(SnO2)n]m.