<s>
General	O
Atomic	O
and	O
Molecular	O
Electronic	O
Structure	O
System	O
(	O
GAMESS-UK	O
)	O
is	O
a	O
computer	O
software	O
program	O
for	O
computational	O
chemistry	O
.	O
</s>
<s>
The	O
original	O
code	O
split	O
in	O
1981	O
into	O
GAMESS-UK	O
and	O
GAMESS	B-Application
(	O
US	O
)	O
variants	O
,	O
which	O
now	O
differ	O
significantly	O
.	O
</s>
<s>
Many	O
of	O
the	O
early	O
developments	O
in	O
the	O
UK	O
version	O
arose	O
from	O
the	O
earlier	O
UK	O
based	O
ATMOL	O
program	O
,	O
which	O
,	O
unlike	O
GAMESS	B-Application
,	O
lacked	O
analytical	O
gradients	O
for	O
geometry	O
optimisation	O
.	O
</s>
<s>
GAMESS-UK	O
can	O
perform	O
many	O
general	O
computational	O
chemistry	O
calculations	O
,	O
including	O
Hartree	O
–	O
Fock	O
method	O
,	O
Møller	O
–	O
Plesset	O
perturbation	O
theory	O
(	O
MP2	O
&	O
MP3	O
)	O
,	O
coupled	O
cluster	O
(	O
CCSD	O
&	O
CCSD(T )	O
)	O
,	O
density	O
functional	O
theory	O
(	O
DFT	O
)	O
,	O
configuration	O
interaction	O
(	O
CI	O
)	O
,	O
and	O
other	O
advanced	O
electronic	O
structure	O
methods	O
.	O
</s>
