<s>
Massively	B-Language
Parallel	I-Language
Quantum	I-Language
Chemistry	I-Language
(	O
MPQC	B-Language
)	O
is	O
an	O
ab	O
initio	O
computational	O
chemistry	O
software	O
program	O
.	O
</s>
<s>
Three	O
features	O
distinguish	O
it	O
from	O
other	O
quantum	O
chemistry	O
programs	O
such	O
as	O
Gaussian	B-Application
and	O
GAMESS	B-Application
:	O
it	O
is	O
open-source	B-Application
,	O
has	O
an	O
object-oriented	B-Language
design	O
,	O
and	O
is	O
created	O
from	O
the	O
beginning	O
as	O
a	O
parallel	B-Operating_System
processing	I-Operating_System
program	O
.	O
</s>
<s>
It	O
is	O
available	O
in	O
Ubuntu	B-Operating_System
and	O
Debian	O
.	O
</s>
<s>
MPQC	B-Language
provides	O
implementations	O
for	O
a	O
number	O
of	O
important	O
methods	O
for	O
calculating	O
electronic	O
structure	O
,	O
including	O
Hartree	O
–	O
Fock	O
,	O
Møller	O
–	O
Plesset	O
perturbation	O
theory	O
(	O
including	O
its	O
explicitly	O
correlated	O
linear	O
R12	O
versions	O
)	O
,	O
and	O
density	O
functional	O
theory	O
.	O
</s>
