<s>
FHI-aims	B-Application
(	O
Fritz	O
Haber	O
Institute	O
ab	O
initio	O
materials	O
simulations	O
)	O
is	O
a	O
software	O
package	O
for	O
computational	O
molecular	O
and	O
materials	O
science	O
written	O
in	O
Fortran	B-Application
.	O
</s>
<s>
Originally	O
developed	O
at	O
the	O
Fritz	O
Haber	O
Institute	O
in	O
Berlin	O
,	O
the	O
ongoing	O
development	O
of	O
the	O
FHI-aims	B-Application
source	O
code	O
is	O
now	O
driven	O
by	O
a	O
worldwide	O
community	O
of	O
collaborating	O
research	O
institutions	O
.	O
</s>
<s>
The	O
FHI-aims	B-Application
software	O
package	O
is	O
an	O
all-electron	O
,	O
full-potential	O
electronic	O
structure	O
code	O
utilizing	O
numeric	O
atom-centered	O
basis	O
functions	O
for	O
its	O
electronic	O
structure	O
calculations	O
.	O
</s>
<s>
The	O
localized	O
basis	O
set	O
enables	O
the	O
accurate	O
treatment	O
of	O
all	O
electrons	O
on	O
the	O
same	O
footing	O
in	O
periodic	B-Algorithm
and	O
non-periodic	O
systems	O
without	O
relying	O
on	O
the	O
approximation	O
for	O
the	O
core	O
states	O
,	O
such	O
as	O
pseudopotentials	O
.	O
</s>
<s>
The	O
workload	O
of	O
the	O
simulations	O
is	O
efficiently	O
distributable	O
for	O
parallel	B-Operating_System
computing	I-Operating_System
using	O
the	O
MPI	B-Application
communication	O
protocol	O
.	O
</s>
<s>
The	O
primary	O
production	O
methods	O
of	O
FHI-aims	B-Application
are	O
density	O
functional	O
theory	O
as	O
well	O
as	O
many-body	O
methods	O
and	O
higher-level	O
quantum	O
chemistry	O
approaches	O
.	O
</s>
<s>
For	O
the	O
exchange-correlation	O
treatment	O
,	O
local	O
(	O
LDA	O
)	O
,	O
semi-local	O
(	O
e.g.	O
,	O
PBE	O
,	O
PBEsol	O
)	O
,	O
meta-GGA	O
,	O
and	O
hybrid	O
(	O
e.g.	O
,	O
HSE06	O
,	O
B3LYP	O
)	O
functionals	O
have	O
been	O
implemented	O
.	O
</s>
<s>
Moreover	O
,	O
thermodynamic	O
properties	O
of	O
the	O
molecules	O
and	O
solids	O
are	O
accessible	O
via	O
Born-Oppenheimer	O
molecular	O
dynamics	O
and	O
path	B-Algorithm
integral	I-Algorithm
molecular	I-Algorithm
dynamics	I-Algorithm
methods	O
.	O
</s>
<s>
Since	O
FHI-aims	B-Application
is	O
an	O
all-electron	O
full-potential	O
code	O
that	O
is	O
computationally	O
efficient	O
without	O
compromising	O
accuracy	O
,	O
the	O
choice	O
of	O
basis	O
function	O
is	O
crucial	O
in	O
order	O
to	O
achieve	O
the	O
said	O
accuracy	O
.	O
</s>
<s>
Therefore	O
,	O
FHI-aims	B-Application
is	O
based	O
on	O
numerically	O
tabulated	O
atom-centered	O
orbitals	O
(	O
NAOs	O
)	O
of	O
the	O
form	O
:	O
</s>
<s>
The	O
first	O
line	O
of	O
code	O
of	O
the	O
actual	O
FHI-aims	B-Application
code	O
was	O
written	O
in	O
late	O
2004	O
,	O
using	O
the	O
atomic	O
solver	O
employed	O
in	O
the	O
Fritz	O
Haber	O
Institute	O
pseudopotential	O
program	O
package	O
fhi98PP	O
as	O
a	O
foundation	O
to	O
obtain	O
radial	O
functions	O
for	O
use	O
as	O
basis	O
functions	O
.	O
</s>
<s>
The	O
first	O
developments	O
benefitted	O
heavily	O
from	O
the	O
excellent	O
set	O
of	O
numerical	O
technologies	O
described	O
in	O
several	O
publications	O
by	O
Bernard	O
Delley	O
and	O
coworkers	O
in	O
the	O
context	O
of	O
the	O
DMol3	B-Application
code	O
,	O
as	O
well	O
as	O
from	O
many	O
broader	O
methodological	O
developments	O
published	O
in	O
the	O
electronic	O
structure	O
theory	O
community	O
over	O
the	O
years	O
.	O
</s>
<s>
Initial	O
efforts	O
in	O
FHI-aims	B-Application
focused	O
on	O
developing	O
a	O
complete	O
numeric	O
atom-centered	O
basis	O
set	O
library	O
for	O
density-functional	O
theory	O
from	O
"	O
light	O
"	O
to	O
highly	O
accurate	O
(	O
few	O
meV/atom	O
)	O
accuracy	O
for	O
total	O
energies	O
,	O
available	O
for	O
all	O
relevant	O
elements	O
(	O
Z	O
=	O
1-102	O
)	O
across	O
the	O
periodic	B-Algorithm
table	O
.	O
</s>
<s>
By	O
2006	O
,	O
work	O
on	O
parallel	O
functionality	O
,	O
support	O
for	O
periodic	B-Algorithm
boundary	I-Algorithm
conditions	I-Algorithm
,	O
total	O
energy	O
gradients	O
(	O
forces	O
)	O
and	O
on	O
exact	O
exchange	B-General_Concept
and	O
many-body	O
perturbation	O
theory	O
had	O
commenced	O
.	O
</s>
