<s>
Psi	B-Application
is	O
an	O
ab	O
initio	O
computational	O
chemistry	O
package	O
originally	O
written	O
by	O
the	O
research	O
group	O
of	O
Henry	O
F	O
.	O
Schaefer	O
,	O
III	O
(	O
University	O
of	O
Georgia	O
)	O
.	O
</s>
<s>
Utilizing	O
Psi	B-Application
,	O
one	O
can	O
perform	O
a	O
calculation	O
on	O
a	O
molecular	O
system	O
with	O
various	O
kinds	O
of	O
methods	O
such	O
as	O
Hartree-Fock	O
,	O
Post-Hartree	O
–	O
Fock	O
electron	O
correlation	O
methods	O
,	O
and	O
density	O
functional	O
theory	O
.	O
</s>
<s>
The	O
major	O
part	O
of	O
the	O
program	O
is	O
written	O
in	O
C++	B-Language
,	O
while	O
Python	B-Language
API	B-General_Concept
is	O
also	O
available	O
,	O
which	O
allows	O
users	O
to	O
perform	O
complex	O
computations	O
or	O
automate	O
tasks	O
easily	O
.	O
</s>
<s>
Psi4	O
is	O
the	O
latest	O
release	O
of	O
the	O
program	O
package	O
-	O
it	O
is	O
open	B-Application
source	I-Application
,	O
released	O
as	O
free	B-Application
under	O
the	O
GPL	B-License
through	O
GitHub	B-Application
.	O
</s>
<s>
Psi4	O
is	O
available	O
on	O
Linux	B-Application
releases	O
such	O
as	O
Fedora	O
and	O
Ubuntu	O
.	O
</s>
<s>
The	O
basic	O
capabilities	O
of	O
Psi	B-Application
are	O
concentrated	O
around	O
the	O
following	O
methods	O
of	O
quantum	O
chemistry	O
:	O
</s>
