<s>
ONETEP	B-Application
(	O
Order-N	O
Electronic	O
Total	O
Energy	O
Package	O
)	O
is	O
a	O
linear-scaling	O
density	O
functional	O
theory	O
software	O
package	O
able	O
to	O
run	O
on	O
parallel	B-Operating_System
computers	I-Operating_System
.	O
</s>
<s>
It	O
uses	O
a	O
basis	O
of	O
non-orthogonal	O
generalized	O
Wannier	O
functions	O
(	O
NGWFs	O
)	O
expressed	O
in	O
terms	O
of	O
periodic	O
cardinal	B-Algorithm
sine	I-Algorithm
(	O
psinc	O
)	O
functions	O
,	O
which	O
are	O
in	O
turn	O
equivalent	O
to	O
a	O
basis	O
of	O
plane-waves	O
.	O
</s>
<s>
ONETEP	B-Application
therefore	O
combines	O
the	O
advantages	O
of	O
the	O
plane-wave	O
approach	O
(	O
controllable	O
accuracy	O
and	O
variational	O
convergence	O
of	O
the	O
total	O
energy	O
with	O
respect	O
to	O
the	O
size	O
of	O
the	O
basis	O
)	O
with	O
computational	O
effort	O
that	O
scales	O
linearly	O
with	O
the	O
size	O
of	O
the	O
system	O
.	O
</s>
<s>
The	O
ONETEP	B-Application
approach	O
involves	O
simultaneous	O
optimization	O
of	O
the	O
density	O
kernel	O
(	O
a	O
generalization	O
of	O
occupation	O
numbers	O
to	O
non-orthogonal	O
basis	O
,	O
which	O
represents	O
the	O
density	O
matrix	O
in	O
the	O
basis	O
of	O
NGWFs	O
)	O
and	O
the	O
NGWFs	O
themselves	O
.	O
</s>
<s>
ONETEP	B-Application
has	O
been	O
developed	O
by	O
a	O
UK-centric	O
group	O
of	O
academics	O
based	O
at	O
the	O
universities	O
of	O
Cambridge	O
,	O
Southampton	O
,	O
Warwick	O
,	O
Imperial	O
College	O
London	O
and	O
Gdańsk	O
University	O
of	O
Technology	O
.	O
</s>
<s>
It	O
is	O
available	O
to	O
academics	O
at	O
a	O
reduced	O
rate	O
,	O
and	O
licenses	O
can	O
be	O
obtained	O
for	O
non-academic	O
usage	O
from	O
the	O
developers	O
or	O
through	O
Accelrys	O
 '	O
Materials	B-Application
Studio	I-Application
package	O
.	O
</s>
