<s>
Car	B-Application
–	I-Application
Parrinello	I-Application
molecular	I-Application
dynamics	I-Application
or	O
CPMD	B-Application
refers	O
to	O
either	O
a	O
method	O
used	O
in	O
molecular	O
dynamics	O
(	O
also	O
known	O
as	O
the	O
Car	B-Application
–	I-Application
Parrinello	I-Application
method	I-Application
)	O
or	O
the	O
computational	O
chemistry	O
software	O
package	O
used	O
to	O
implement	O
this	O
method	O
.	O
</s>
<s>
The	O
CPMD	B-Application
method	O
is	O
one	O
of	O
the	O
major	O
methods	O
for	O
calculating	O
ab-initio	O
molecular	O
dynamics	O
(	O
ab-inito	O
MD	O
or	O
AIMD	O
)	O
.	O
</s>
<s>
The	O
CPMD	B-Application
method	O
is	O
related	O
to	O
the	O
more	O
common	O
Born	O
–	O
Oppenheimer	O
molecular	O
dynamics	O
(	O
BOMD	O
)	O
method	O
in	O
that	O
the	O
quantum	O
mechanical	O
effect	O
of	O
the	O
electrons	O
is	O
included	O
in	O
the	O
calculation	O
of	O
energy	O
and	O
forces	O
for	O
the	O
classical	O
motion	O
of	O
the	O
nuclei	O
.	O
</s>
<s>
CPMD	B-Application
and	O
BOMD	O
are	O
different	O
types	O
of	O
AIMD	O
.	O
</s>
<s>
However	O
,	O
whereas	O
BOMD	O
treats	O
the	O
electronic	O
structure	O
problem	O
within	O
the	O
time-independent	O
Schrödinger	O
equation	O
,	O
CPMD	B-Application
explicitly	O
includes	O
the	O
electrons	O
as	O
active	O
degrees	O
of	O
freedom	O
,	O
via	O
(	O
fictitious	O
)	O
dynamical	O
variables	O
.	O
</s>
<s>
The	O
Car	B-Application
–	I-Application
Parrinello	I-Application
method	I-Application
is	O
a	O
type	O
of	O
molecular	O
dynamics	O
,	O
usually	O
employing	O
periodic	O
boundary	O
conditions	O
,	O
planewave	O
basis	O
sets	O
,	O
and	O
density	O
functional	O
theory	O
,	O
proposed	O
by	O
Roberto	O
Car	O
and	O
Michele	O
Parrinello	O
in	O
1985	O
,	O
who	O
were	O
subsequently	O
awarded	O
the	O
Dirac	O
Medal	O
by	O
ICTP	O
in	O
2009	O
.	O
</s>
<s>
In	O
contrast	O
to	O
Born	O
–	O
Oppenheimer	O
molecular	O
dynamics	O
wherein	O
the	O
nuclear	O
(	O
ions	O
)	O
degree	O
of	O
freedom	O
are	O
propagated	O
using	O
ionic	O
forces	O
which	O
are	O
calculated	O
at	O
each	O
iteration	O
by	O
approximately	O
solving	O
the	O
electronic	O
problem	O
with	O
conventional	O
matrix	B-Algorithm
diagonalization	I-Algorithm
methods	O
,	O
the	O
CarParrinello	O
method	O
explicitly	O
introduces	O
the	O
electronic	O
degrees	O
of	O
freedom	O
as	O
(	O
fictitious	O
)	O
dynamical	O
variables	O
,	O
writing	O
an	O
extended	O
Lagrangian	O
for	O
the	O
system	O
which	O
leads	O
to	O
a	O
system	O
of	O
coupled	O
equations	O
of	O
motion	O
for	O
both	O
ions	O
and	O
electrons	O
.	O
</s>
<s>
Currently	O
,	O
the	O
CPMD	B-Application
method	O
can	O
be	O
applied	O
to	O
systems	O
that	O
consist	O
of	O
a	O
few	O
tens	O
or	O
hundreds	O
of	O
atoms	O
and	O
access	O
timescales	O
on	O
the	O
order	O
of	O
tens	O
of	O
picoseconds	O
.	O
</s>
<s>
In	O
CPMD	B-Application
the	O
core	O
electrons	O
are	O
usually	O
described	O
by	O
a	O
pseudopotential	O
and	O
the	O
wavefunction	O
of	O
the	O
valence	O
electrons	O
are	O
approximated	O
by	O
a	O
plane	O
wave	O
basis	O
set	O
.	O
</s>
<s>
the	O
Verlet	B-Language
integration	I-Language
algorithm	O
)	O
.	O
</s>
<s>
Compared	O
to	O
BOMD	O
,	O
CPMD	B-Application
allows	O
for	O
a	O
more	O
accurate	O
description	O
of	O
the	O
electronic	O
structure	O
and	O
results	O
in	O
a	O
more	O
accurate	O
simulation	O
of	O
the	O
system	O
.	O
</s>
<s>
However	O
,	O
CPMD	B-Application
is	O
computationally	O
demanding	O
and	O
requires	O
significant	O
computational	O
resources	O
.	O
</s>
<s>
CPMD	B-Application
is	O
an	O
approximation	O
of	O
the	O
Born	O
–	O
Oppenheimer	O
MD	O
(	O
BOMD	O
)	O
method	O
.	O
</s>
<s>
In	O
BOMD	O
,	O
the	O
electrons	O
 '	O
wave	O
function	O
must	O
be	O
minimized	O
via	O
matrix	B-Algorithm
diagonalization	I-Algorithm
at	O
every	O
step	O
in	O
the	O
trajectory	O
.	O
</s>
<s>
CPMD	B-Application
uses	O
fictitious	O
dynamics	O
to	O
keep	O
the	O
electrons	O
close	O
to	O
the	O
ground	O
state	O
,	O
preventing	O
the	O
need	O
for	O
a	O
costly	O
self-consistent	O
iterative	O
minimization	O
at	O
each	O
time	O
step	O
.	O
</s>
<s>
CP2K	B-Application
:	O
an	O
open-source	O
software	O
package	O
for	O
AIMD	O
.	O
</s>
<s>
Quantum	B-Application
Espresso	I-Application
:	O
an	O
open-source	O
package	O
for	O
performing	O
DFT	O
calculations	O
.	O
</s>
<s>
VASP	B-Application
:	O
a	O
commercial	O
software	O
package	O
for	O
performing	O
DFT	O
calculations	O
.	O
</s>
<s>
Gaussian	B-Application
:	O
a	O
commercial	O
software	O
package	O
that	O
can	O
perform	O
AIMD	O
.	O
</s>
<s>
NWChem	B-Application
:	O
an	O
open-source	O
software	O
package	O
for	O
AIMD	O
.	O
</s>
<s>
LAMMPS	B-Application
:	O
an	O
open-source	O
software	O
package	O
for	O
performing	O
classical	O
and	O
ab	O
initio	O
MD	O
simulations	O
.	O
</s>
<s>
SIESTA	B-Application
:	O
an	O
open-source	O
software	O
package	O
for	O
AIMD	O
.	O
</s>
<s>
Solving	O
the	O
heat	O
transfer	O
problems	O
(	O
heat	O
conduction	O
and	O
thermal	O
radiation	O
)	O
between	O
Si/Ge	O
superlattices	B-General_Concept
.	O
</s>
<s>
Predicting	O
the	O
amorphous	O
phase	O
of	O
the	O
phase-change	B-Device
memory	I-Device
material	O
GeSbTe	O
.	O
</s>
