  The Order (N) Tight Binding Molecular Dynamics (TBMD) algorithms applied to
simulate the tensile elongations of short (2-2.5 nm) armchair and zigzag Single
Walled Carbon Nanotubes (SWCNTs) without bond breakings or defect formation.
Simulations are repeated at high temperatures. We fix the lower limit of
breaking strains to short SWCNTs without bond breaking or 5-7 defects
formation. At room temperature, the simulated (4,4) SWCNT is able to carry the
strain up to 130% of the relaxed tube length without bond breaking or 5-7
defects formation. This value is 127% for (11,0) SWCNT, 125% for (17,0) SWCNT,
123% for (10,10) SWCNT. In defect free, short nanotubes as the nanotube's
radius increase the bond-breakings occur at lower strain values regardless of
their chirality. This is true when we heat the tubes to higher temperatures.
Bond breaking strain values, tensile strength, Young's modulus of the SWCNTs
are obtained as functions of temperature. Defect free zigzag nanotubes exhibit
higher tensile strength than armchaired ones. Young's modulus of defect free
individual singlewall nanotubes is found to be in the range of 0.400 TPa within
the elastic limit. At room temperature and experimentally realizable strain
values, thinner tubes are more resistant to bond breaking and zigzag tubes over
armchair ones. At high temperatures although the resistance to strain drops the
same trend still holds. We observe a slight decrease of the tensile strength
with increasing temperatures. The same trend is also observed in the Young's
modulus. Results are important in determining a true breaking strains of
SWCNTs.
