Stretching carbon nanotubes

(4,4) tube

Simulations with a Nose-Hoover thermostat

set.2: (4,4) tube; 1500.0 K; 0.062643 Ang/ps;
In all simulations performed, the tubes stretch uniformly, and then break.
set.3: (4,4) tube with a Stone-Wales defect; 1500.0 K; 0.062643 Ang/ps;
A bit better: Two double wires, and one normal five atom wire out of 10 runs.
set.5: (4,4) tube with a vacancy; 1500.0 K; -0.062643 Ang/ps;
Just four runs. A bit mess. Contracting tubes is not really pretty ;)
set.1: (4,4) tube with a vacancy; 1500.0 K; 0.062643 Ang/ps;
The first run is a good evidence for "necking". Plus another 4/10 wires.
set.4: (4,4) tube with a vacancy; 1500.0 K; 0.12528 Ang/ps;
3/10 wires. In one case there is ejection fo an C₂.
set.6: (4,4) tube with a vacancy; 1500.0 K; 0.25056 Ang/ps;,
4/10 wires, one of which is an amazing 12 atoms long.
set.7: (4,4) tube with a vacancy; 1500.0 K; 0.50111 Ang/ps;
Onle one wire is formed. It is a bit too fast pulling, I would say.
set.8: (4,4) tube with a vacancy; 320.0 K; 0.12528 Ang/ps; All tubes break.

set.10: (4,4) tube with a vacancy; 320.0 K; 0.06264 Ang/ps;
7/10 times there is a wire formed. The best conditions for the formation of a wire till now.
set.9: (4,4) tube with a vacancy; 320.0 K; 0.12528 Ang/ps;
3/10 times (maybe more) there is a wire formed between the tubes.
set.11: (4,4) tube with a vacancy; 1500.0 K; 0.12528 Ang/ps;
7/10 times there is a wire or more complex structure formed. Due to the high temperature, very complicated restructuring of the tube happens.
set.12: (4,4) tube; 320.0 K; 0.12528 Ang/ps;
Tube always breaks, then the temperature raises very quickly sometimes to 10000K, which destroys the tube in rather spectacular ways.
set.13: (4,4) tube with a Stone-Wales defect; 320.0 K; 0.12528 Ang/ps;
In almost all simulations, the tube simply breaks. Seems that a Stone-Wales defect is not enough. The tube elongates too much, and when the plastic deformation happens, the temperature raises so much that no wire can survive. Not as spectacular as set.12, though.
set.14: (4,4) tube with a vacancy; 320.0 K; -0.06264 Ang/ps;
The most unintersting set of all. The tube always deforms in the same way, into a shape I have problems describing in english.

(4,0) tube

set.15: (4,0) tube; 320.0 K; 0.30390 Ang/ps;
As expected, very similar to set.12. Just tubes breaking in violent ways.
set.16: (4,0) tube with a vacancy; 320.0 K; 0.15195 Ang/ps;
Only 2/10 wires are formed. It seems that the concentration of defects is too low. When the tube starts breaking, the two sides are pulled too violently by the streched tube, which breaks the (potential) wire.
set.17: (4,0) tube with atwo vacancy; 320.0 K; 0.15195 Ang/ps;
Always got long wires. The longest of which was 16 atoms long. Some of them broke when having around 10-12 atoms, others not. Twice there was an ejection of C₂.

(4,0) tube