<s>
CoNTub	B-Language
is	O
a	O
software	O
project	O
written	O
in	O
Java	B-Language
which	O
runs	O
on	O
Windows	B-Application
,	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
,	O
Linux	B-Application
and	O
Unix	B-Application
Operating	I-Application
systems	I-Application
through	O
any	O
Java-enabled	O
web	O
browser	O
.	O
</s>
<s>
CoNTub	B-Language
1.0[1]	O
was	O
the	O
first	O
implementation	O
for	O
building	O
these	O
complex	O
structures	O
and	O
included	O
nanotube	O
heterojunctions	O
,	O
while	O
CoNTub	B-Language
2.0[2]	O
is	O
mainly	O
devoted	O
to	O
three-nanotube	O
junctions	O
.	O
</s>
<s>
CoNTub	B-Language
is	O
based	O
on	O
the	O
strip	O
algebra	O
,	O
and	O
is	O
able	O
to	O
find	O
the	O
unique	O
structure	O
for	O
connecting	O
two	O
specific	O
and	O
arbitrary	O
carbon	O
nanotubes	O
and	O
many	O
of	O
the	O
possible	O
three-tube	O
junctions	O
.	O
</s>
<s>
CoNTub	B-Language
generates	O
the	O
geometry	O
of	O
various	O
types	O
of	O
nanotube	O
junctions	O
,	O
i.e.	O
,	O
nanotube	O
heterojunctions	O
and	O
three-nanotube	O
junctions	O
,	O
including	O
also	O
single-walled	O
nanotubes	O
(	O
SWNTs	O
)	O
and	O
multi-walled	O
nanotubes	O
(	O
MWNTs	O
)	O
.	O
</s>
<s>
Although	O
the	O
current	O
version	O
of	O
CoNTub	B-Language
is	O
v2.0	O
,	O
this	O
version	O
does	O
not	O
supersedes	O
v1.0	O
,	O
as	O
v2.0	O
is	O
dedicated	O
currently	O
to	O
only	O
three-nanotube	O
junctions	O
,	O
although	O
the	O
incorporation	O
of	O
v1.0	O
functionality	O
into	O
v.2.0	O
is	O
planned	O
.	O
</s>
<s>
CoNTub	B-Language
v1.0	O
is	O
organized	O
in	O
five	O
Tabbed	O
panels	O
CoNTub[1],	O
the	O
first	O
three	O
being	O
dedicated	O
to	O
structure	O
generation	O
,	O
the	O
fourth	O
to	O
the	O
output	O
in	O
PDB	O
format	O
,	O
and	O
the	O
fifth	O
contains	O
a	O
short	O
help	O
section	O
.	O
</s>
<s>
CoNTub	B-Language
v2.0	O
has	O
experimented	O
a	O
major	O
redesign	O
,	O
and	O
the	O
panes	O
have	O
been	O
removed	O
,	O
instead	O
,	O
a	O
conventional	O
menubar	O
has	O
been	O
added	O
where	O
the	O
type	O
of	O
structure	O
to	O
be	O
generated	O
can	O
be	O
chosen	O
.	O
</s>
<s>
ConTub	B-Language
displays	O
the	O
resulting	O
nanotube	O
,	O
as	O
well	O
as	O
its	O
electronic	O
band	O
structure	O
and	O
density	O
of	O
states	O
(	O
DOS	O
)	O
,	O
following	O
a	O
tight	O
binding	O
model	O
.	O
</s>
<s>
The	O
default	O
value	O
for	O
spacing	O
corresponds	O
to	O
the	O
standard	O
distance	O
between	O
layers	O
in	O
crystalline	O
graphite	B-Application
(	O
3.4	O
Å	O
)	O
.	O
</s>
<s>
ConTub	B-Language
automatically	O
selects	O
the	O
indices	O
of	O
the	O
remaining	O
tubes	O
,	O
trying	O
to	O
adjust	O
the	O
interlayer	O
spacing	O
,	O
and	O
tries	O
to	O
use	O
tubes	O
with	O
the	O
same	O
chirality	O
as	O
that	O
of	O
the	O
inner	O
nanotube	O
.	O
</s>
<s>
This	O
is	O
the	O
core	O
of	O
the	O
CoNTub[1]	O
program	O
.	O
</s>
<s>
with	O
the	O
lowest	O
number	O
of	O
non-hexagonal	O
rings	O
(	O
a	O
pentagon	B-Device
and	O
a	O
heptagon	O
)	O
,	O
also	O
called	O
defects	O
or	O
disclinations	O
.	O
</s>
<s>
A	O
further	O
implementation	O
of	O
the	O
Strip	O
Algebra	O
has	O
been	O
released	O
in	O
the	O
second	O
version	O
of	O
CoNTub	B-Language
,	O
in	O
order	O
to	O
elucidate	O
the	O
precise	O
location	O
of	O
atoms	O
and	O
rings	O
that	O
lead	O
to	O
a	O
junction	O
of	O
three	O
nanotubes	O
.	O
</s>
<s>
Connection	O
between	O
three	O
nanotubes	O
requires	O
,	O
at	O
least	O
,	O
the	O
presence	O
of	O
six	O
heptagons	O
,	O
instead	O
of	O
the	O
single	O
pentagon	B-Device
and	O
heptagon	O
required	O
for	O
an	O
heterojunction	O
.	O
</s>
<s>
Imposing	O
additional	O
restrictions	O
to	O
the	O
geometry	O
can	O
ease	O
the	O
finding	O
of	O
viable	O
geometries	O
,	O
and	O
this	O
is	O
what	O
is	O
applied	O
in	O
the	O
current	O
version	O
of	O
CoNTub	B-Language
:	O
Forcing	O
the	O
tubes	O
connected	O
to	O
be	O
of	O
the	O
same	O
kind	O
,	O
and	O
forcing	O
an	O
additional	O
C3	O
symmetry	O
,	O
an	O
automated	O
way	O
to	O
construct	O
the	O
geometry	O
can	O
be	O
found	O
.	O
</s>
