<s>
RMG	B-Application
(	O
Real	O
Space	O
MultiGrid	O
)	O
is	O
an	O
open	B-Application
source	I-Application
density	O
functional	O
theory	O
electronic	O
structure	O
code	O
distributed	O
under	O
the	O
GNU	B-License
General	I-License
Public	I-License
License	I-License
.	O
</s>
<s>
RMG	B-Application
is	O
highly	O
scalable	O
;	O
it	O
has	O
been	O
run	O
on	O
supercomputers	O
with	O
thousands	O
of	O
CPU	O
cores	O
.	O
</s>
<s>
RMG	B-Application
's	O
main	O
feature	O
is	O
that	O
it	O
uses	O
real-space	O
mesh	O
as	O
a	O
basis	O
,	O
rather	O
plane	O
waves	O
or	O
other	O
types	O
of	O
basis	O
set	O
functions	O
.	O
</s>
<s>
This	O
avoids	O
the	O
need	O
for	O
Fourier	B-Algorithm
transforms	I-Algorithm
,	O
and	O
makes	O
RMG	B-Application
highly	O
scalable	O
.	O
</s>
<s>
Domain	B-Algorithm
decomposition	I-Algorithm
is	O
used	O
to	O
assign	O
different	O
regions	O
of	O
space	O
to	O
individual	O
CPU	O
cores	O
or	O
nodes	O
.	O
</s>
<s>
RMG	B-Application
scales	O
nearly	O
linearly	O
up	O
to	O
100k	O
processor	O
cores	O
and	O
20k	O
GPUs	O
on	O
Cray	O
XK6	O
.	O
</s>
<s>
RMG	B-Application
was	O
originally	O
developed	O
in	O
1993	O
–	O
1994	O
at	O
North	O
Carolina	O
State	O
University	O
.	O
</s>
<s>
It	O
was	O
written	O
in	O
C	O
with	O
small	O
parts	O
being	O
in	O
FORTRAN	B-Application
.	O
</s>
<s>
MPI	B-Application
is	O
used	O
for	O
inter-node	O
communication	O
and	O
C++11	B-Language
threads	O
for	O
intra-node	O
parallelization	O
.	O
</s>
<s>
Other	O
libraries	O
used	O
are	O
Lapack	B-Application
,	O
ScaLAPACK	B-Application
,	O
FFTW	B-Application
,	O
libxc	O
and	O
spglib	O
.	O
</s>
<s>
RMG	B-Application
runs	O
on	O
laptops	O
,	O
desktops	O
,	O
workstations	O
,	O
clusters	O
or	O
supercomputers	O
.	O
</s>
<s>
It	O
can	O
run	O
on	O
Linux	B-Application
,	O
Unix	B-Application
,	O
Windows	B-Application
and	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
operating	O
systems	O
.	O
</s>
