<s>
OpenAtom	B-Application
is	O
a	O
massively	O
parallel	O
quantum	O
chemistry	O
application	O
written	O
in	O
Charm++	B-Language
for	O
simulations	O
on	O
supercomputers	O
.	O
</s>
<s>
Its	O
developmental	O
version	O
was	O
called	O
LeanCP	B-Application
.	O
</s>
<s>
A	O
particular	O
approach	O
that	O
has	O
proved	O
to	O
be	O
relatively	O
efficient	O
and	O
useful	O
is	O
Car-Parrinello	B-Application
ab	O
initio	O
molecular	O
dynamics	O
(	O
CPAIMD	O
)	O
.	O
</s>
<s>
Using	O
Charm++	B-Language
and	O
its	O
concept	O
of	O
processor	O
virtualization	O
,	O
the	O
phases	O
are	O
discretized	O
into	O
multiple	O
virtual	O
processors	O
which	O
are	O
,	O
in	O
turn	O
,	O
mapped	O
flexibly	O
onto	O
physical	O
processors	O
,	O
thereby	O
allowing	O
significant	O
interleaving	O
of	O
work	O
.	O
</s>
<s>
OpenAtom	B-Application
has	O
shown	O
good	O
scaling	O
up	O
to	O
262,144	O
cores	O
of	O
IBM	O
Blue	O
Gene/Q	O
and	O
131,072	O
cores	O
of	O
Blue	O
Waters	O
,	O
a	O
Cray	O
XE6/XK7	O
system	O
at	O
NCSA	O
.	O
</s>
<s>
OpenAtom	B-Application
is	O
freely	O
available	O
for	O
download	O
at	O
the	O
OpenAtom	B-Application
.	O
</s>
