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fix_nve.cpp
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Tue, Aug 20, 16:38
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text/x-c
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Thu, Aug 22, 16:38 (1 d, 22 h)
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rLAMMPS lammps
fix_nve.cpp
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/* ----------------------------------------------------------------------
LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
http://lammps.sandia.gov, Sandia National Laboratories
Steve Plimpton, sjplimp@sandia.gov
Copyright (2003) Sandia Corporation. Under the terms of Contract
DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
certain rights in this software. This software is distributed under
the GNU General Public License.
See the README file in the top-level LAMMPS directory.
------------------------------------------------------------------------- */
#include "stdio.h"
#include "string.h"
#include "fix_nve.h"
#include "atom.h"
#include "force.h"
#include "update.h"
#include "respa.h"
#include "error.h"
using
namespace
LAMMPS_NS
;
using
namespace
FixConst
;
/* ---------------------------------------------------------------------- */
FixNVE
::
FixNVE
(
LAMMPS
*
lmp
,
int
narg
,
char
**
arg
)
:
Fix
(
lmp
,
narg
,
arg
)
{
if
(
strcmp
(
style
,
"nve/sphere"
)
!=
0
&&
narg
<
3
)
error
->
all
(
FLERR
,
"Illegal fix nve command"
);
dynamic_group_allow
=
1
;
time_integrate
=
1
;
}
/* ---------------------------------------------------------------------- */
int
FixNVE
::
setmask
()
{
int
mask
=
0
;
mask
|=
INITIAL_INTEGRATE
;
mask
|=
FINAL_INTEGRATE
;
mask
|=
INITIAL_INTEGRATE_RESPA
;
mask
|=
FINAL_INTEGRATE_RESPA
;
return
mask
;
}
/* ---------------------------------------------------------------------- */
void
FixNVE
::
init
()
{
dtv
=
update
->
dt
;
dtf
=
0.5
*
update
->
dt
*
force
->
ftm2v
;
if
(
strstr
(
update
->
integrate_style
,
"respa"
))
step_respa
=
((
Respa
*
)
update
->
integrate
)
->
step
;
}
/* ----------------------------------------------------------------------
allow for both per-type and per-atom mass
------------------------------------------------------------------------- */
void
FixNVE
::
initial_integrate
(
int
vflag
)
{
double
dtfm
;
// update v and x of atoms in group
double
**
x
=
atom
->
x
;
double
**
v
=
atom
->
v
;
double
**
f
=
atom
->
f
;
double
*
rmass
=
atom
->
rmass
;
double
*
mass
=
atom
->
mass
;
int
*
type
=
atom
->
type
;
int
*
mask
=
atom
->
mask
;
int
nlocal
=
atom
->
nlocal
;
if
(
igroup
==
atom
->
firstgroup
)
nlocal
=
atom
->
nfirst
;
if
(
rmass
)
{
for
(
int
i
=
0
;
i
<
nlocal
;
i
++
)
if
(
mask
[
i
]
&
groupbit
)
{
dtfm
=
dtf
/
rmass
[
i
];
v
[
i
][
0
]
+=
dtfm
*
f
[
i
][
0
];
v
[
i
][
1
]
+=
dtfm
*
f
[
i
][
1
];
v
[
i
][
2
]
+=
dtfm
*
f
[
i
][
2
];
x
[
i
][
0
]
+=
dtv
*
v
[
i
][
0
];
x
[
i
][
1
]
+=
dtv
*
v
[
i
][
1
];
x
[
i
][
2
]
+=
dtv
*
v
[
i
][
2
];
}
}
else
{
for
(
int
i
=
0
;
i
<
nlocal
;
i
++
)
if
(
mask
[
i
]
&
groupbit
)
{
dtfm
=
dtf
/
mass
[
type
[
i
]];
v
[
i
][
0
]
+=
dtfm
*
f
[
i
][
0
];
v
[
i
][
1
]
+=
dtfm
*
f
[
i
][
1
];
v
[
i
][
2
]
+=
dtfm
*
f
[
i
][
2
];
x
[
i
][
0
]
+=
dtv
*
v
[
i
][
0
];
x
[
i
][
1
]
+=
dtv
*
v
[
i
][
1
];
x
[
i
][
2
]
+=
dtv
*
v
[
i
][
2
];
}
}
}
/* ---------------------------------------------------------------------- */
void
FixNVE
::
final_integrate
()
{
double
dtfm
;
// update v of atoms in group
double
**
v
=
atom
->
v
;
double
**
f
=
atom
->
f
;
double
*
rmass
=
atom
->
rmass
;
double
*
mass
=
atom
->
mass
;
int
*
type
=
atom
->
type
;
int
*
mask
=
atom
->
mask
;
int
nlocal
=
atom
->
nlocal
;
if
(
igroup
==
atom
->
firstgroup
)
nlocal
=
atom
->
nfirst
;
if
(
rmass
)
{
for
(
int
i
=
0
;
i
<
nlocal
;
i
++
)
if
(
mask
[
i
]
&
groupbit
)
{
dtfm
=
dtf
/
rmass
[
i
];
v
[
i
][
0
]
+=
dtfm
*
f
[
i
][
0
];
v
[
i
][
1
]
+=
dtfm
*
f
[
i
][
1
];
v
[
i
][
2
]
+=
dtfm
*
f
[
i
][
2
];
}
}
else
{
for
(
int
i
=
0
;
i
<
nlocal
;
i
++
)
if
(
mask
[
i
]
&
groupbit
)
{
dtfm
=
dtf
/
mass
[
type
[
i
]];
v
[
i
][
0
]
+=
dtfm
*
f
[
i
][
0
];
v
[
i
][
1
]
+=
dtfm
*
f
[
i
][
1
];
v
[
i
][
2
]
+=
dtfm
*
f
[
i
][
2
];
}
}
}
/* ---------------------------------------------------------------------- */
void
FixNVE
::
initial_integrate_respa
(
int
vflag
,
int
ilevel
,
int
iloop
)
{
dtv
=
step_respa
[
ilevel
];
dtf
=
0.5
*
step_respa
[
ilevel
]
*
force
->
ftm2v
;
// innermost level - NVE update of v and x
// all other levels - NVE update of v
if
(
ilevel
==
0
)
initial_integrate
(
vflag
);
else
final_integrate
();
}
/* ---------------------------------------------------------------------- */
void
FixNVE
::
final_integrate_respa
(
int
ilevel
,
int
iloop
)
{
dtf
=
0.5
*
step_respa
[
ilevel
]
*
force
->
ftm2v
;
final_integrate
();
}
/* ---------------------------------------------------------------------- */
void
FixNVE
::
reset_dt
()
{
dtv
=
update
->
dt
;
dtf
=
0.5
*
update
->
dt
*
force
->
ftm2v
;
}
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