<s>
Qbox	B-Application
is	O
an	O
open-source	B-Application
software	I-Application
package	O
for	O
atomic-scale	O
simulations	O
of	O
molecules	O
,	O
liquids	O
and	O
solids	O
.	O
</s>
<s>
Qbox	B-Application
is	O
released	O
under	O
a	O
GNU	B-License
General	I-License
Public	I-License
License	I-License
(	O
GPL	B-License
)	O
with	O
documentation	O
provided	O
at	O
.	O
</s>
<s>
It	O
is	O
available	O
as	O
a	O
FreeBSD	B-Operating_System
port	O
.	O
</s>
<s>
Qbox	B-Application
computes	O
molecular	O
dynamics	O
trajectories	O
of	O
atoms	O
using	O
Newton	O
's	O
equations	O
of	O
motion	O
,	O
with	O
forces	O
derived	O
from	O
electronic	O
structure	O
calculations	O
performed	O
using	O
Density	O
Functional	O
Theory	O
.	O
</s>
<s>
Simulations	O
can	O
be	O
performed	O
either	O
within	O
the	O
Born-Oppenheimer	O
approximation	O
or	O
using	O
Car-Parrinello	B-Application
molecular	I-Application
dynamics	I-Application
.	O
</s>
<s>
Various	O
levels	O
of	O
Density	O
Functional	O
Theory	O
approximations	O
can	O
be	O
used	O
,	O
including	O
the	O
local-density	O
approximation	O
(	O
LDA	O
)	O
,	O
the	O
generalized	O
gradient	O
approximation	O
(	O
GGA	O
)	O
,	O
or	O
hybrid	O
functionals	O
that	O
incorporate	O
a	O
fraction	O
of	O
Hartree-Fock	O
exchange	B-General_Concept
energy	I-General_Concept
.	O
</s>
<s>
Qbox	B-Application
is	O
written	O
in	O
C++	B-Language
and	O
implements	O
parallelism	O
using	O
both	O
the	O
message	B-Application
passing	I-Application
interface	I-Application
(	O
MPI	O
)	O
and	O
the	O
OpenMP	B-Application
application	O
programming	O
interface	O
.	O
</s>
<s>
It	O
makes	O
use	O
of	O
the	O
BLAS	B-Application
,	O
LAPACK	B-Application
,	O
ScaLAPACK	B-Application
,	O
FFTW	B-Application
and	O
Apache	B-Language
Xerces	I-Language
libraries	O
.	O
</s>
<s>
Qbox	B-Application
was	O
designed	O
for	O
operation	O
on	O
massively	B-Operating_System
parallel	I-Operating_System
computers	I-Operating_System
such	O
as	O
the	O
IBM	B-Operating_System
Blue	I-Operating_System
Gene	I-Operating_System
supercomputer	O
,	O
or	O
the	O
Cray	B-Device
XC40	I-Device
supercomputer	O
.	O
</s>
<s>
In	O
2006	O
it	O
was	O
used	O
to	O
establish	O
a	O
performance	O
record	O
on	O
the	O
BlueGene/L	B-Operating_System
computer	O
installed	O
at	O
the	O
Lawrence	O
Livermore	O
National	O
Laboratory	O
.	O
</s>
<s>
The	O
functionality	O
of	O
Qbox	B-Application
can	O
be	O
enhanced	O
by	O
coupling	O
it	O
with	O
other	O
simulation	O
software	O
using	O
a	O
client-server	B-Operating_System
paradigm	O
.	O
</s>
<s>
Examples	O
of	O
Qbox	B-Application
coupled	O
operation	O
include	O
:	O
</s>
