<s>
Octopus	B-Application
is	O
a	O
software	O
package	O
for	O
performing	O
KohnSham	O
density	O
functional	O
theory	O
(	O
DFT	O
)	O
and	O
time-dependent	O
density	O
functional	O
theory	O
(	O
TDDFT	O
)	O
calculations	O
.	O
</s>
<s>
Octopus	B-Application
employs	O
pseudopotentials	O
and	O
real-space	O
numerical	O
grids	O
to	O
propagate	O
the	O
KohnSham	O
orbitals	O
in	O
real	O
time	O
under	O
the	O
influence	O
of	O
time-varying	O
electromagnetic	O
fields	O
.	O
</s>
<s>
Octopus	B-Application
can	O
calculate	O
static	O
and	O
dynamic	O
polarizabilities	O
and	O
first	O
hyperpolarizabilities	O
,	O
static	O
magnetic	O
susceptibilities	O
,	O
absorption	O
spectra	O
,	O
and	O
perform	O
molecular	O
dynamics	O
simulations	O
with	O
Ehrenfest	O
and	O
Car	B-Application
–	I-Application
Parrinello	I-Application
methods	I-Application
.	O
</s>
<s>
The	O
code	O
is	O
written	O
predominantly	O
in	O
Fortran	B-Application
,	O
with	O
some	O
C	B-Language
and	O
Perl	B-Language
.	O
</s>
<s>
It	O
is	O
released	O
under	O
the	O
GPL	B-License
.	O
</s>
<s>
In	O
the	O
immediate	O
future	O
,	O
extension	O
of	O
these	O
procedures	O
to	O
systems	O
that	O
are	O
infinite	O
and	O
periodic	O
in	O
one	O
or	O
more	O
dimensions	O
(	O
polymers	B-Language
,	O
slabs	O
,	O
nanotubes	O
,	O
solids	O
)	O
,	O
and	O
to	O
electronic	O
transport	O
.	O
</s>
<s>
In	O
consequence	O
,	O
it	O
allows	O
for	O
multiple	O
task	O
divisions	O
,	O
this	O
utilises	O
mesh	O
division	O
software	O
,	O
MPI	B-Application
and	O
OpenMP	B-Application
.	O
</s>
<s>
The	O
language	O
of	O
most	O
of	O
the	O
code	O
is	O
Fortran	B-Application
90	O
(	O
almost	O
50.000	O
lines	O
at	O
present	O
)	O
.	O
</s>
<s>
Other	O
languages	O
,	O
such	O
as	O
C	B-Language
or	O
Perl	B-Language
,	O
are	O
also	O
used	O
.	O
</s>
<s>
The	O
package	O
is	O
licensed	O
under	O
the	O
GNU	B-License
General	I-License
Public	I-License
License	I-License
(	O
GPL	B-License
)	O
.	O
</s>
