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fix_drag.cpp
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Created
Mon, Oct 7, 14:30
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3 KB
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text/x-c
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Wed, Oct 9, 14:30 (2 d)
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blob
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21410849
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rLAMMPS lammps
fix_drag.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 "math.h"
#include "stdlib.h"
#include "string.h"
#include "fix_drag.h"
#include "atom.h"
#include "update.h"
#include "respa.h"
#include "domain.h"
#include "error.h"
using
namespace
LAMMPS_NS
;
/* ---------------------------------------------------------------------- */
FixDrag
::
FixDrag
(
LAMMPS
*
lmp
,
int
narg
,
char
**
arg
)
:
Fix
(
lmp
,
narg
,
arg
)
{
if
(
narg
!=
8
)
error
->
all
(
"Illegal fix drag command"
);
xflag
=
yflag
=
zflag
=
1
;
if
(
strcmp
(
arg
[
3
],
"NULL"
)
==
0
)
xflag
=
0
;
else
xc
=
atof
(
arg
[
3
]);
if
(
strcmp
(
arg
[
4
],
"NULL"
)
==
0
)
yflag
=
0
;
else
yc
=
atof
(
arg
[
4
]);
if
(
strcmp
(
arg
[
5
],
"NULL"
)
==
0
)
zflag
=
0
;
else
zc
=
atof
(
arg
[
5
]);
f_mag
=
atof
(
arg
[
6
]);
delta
=
atof
(
arg
[
7
]);
}
/* ---------------------------------------------------------------------- */
int
FixDrag
::
setmask
()
{
int
mask
=
0
;
mask
|=
POST_FORCE
;
mask
|=
POST_FORCE_RESPA
;
return
mask
;
}
/* ---------------------------------------------------------------------- */
void
FixDrag
::
init
()
{
if
(
strcmp
(
update
->
integrate_style
,
"respa"
)
==
0
)
nlevels_respa
=
((
Respa
*
)
update
->
integrate
)
->
nlevels
;
}
/* ---------------------------------------------------------------------- */
void
FixDrag
::
setup
()
{
if
(
strcmp
(
update
->
integrate_style
,
"verlet"
)
==
0
)
post_force
(
1
);
else
{
((
Respa
*
)
update
->
integrate
)
->
copy_flevel_f
(
nlevels_respa
-
1
);
post_force_respa
(
1
,
nlevels_respa
-
1
,
0
);
((
Respa
*
)
update
->
integrate
)
->
copy_f_flevel
(
nlevels_respa
-
1
);
}
}
/* ---------------------------------------------------------------------- */
void
FixDrag
::
post_force
(
int
vflag
)
{
// apply drag force to atoms in group of magnitude f_mag
// apply in direction (r-r0) if atom is further than delta away
double
**
x
=
atom
->
x
;
double
**
f
=
atom
->
f
;
int
*
mask
=
atom
->
mask
;
int
nlocal
=
atom
->
nlocal
;
double
dx
,
dy
,
dz
,
r
,
prefactor
;
for
(
int
i
=
0
;
i
<
nlocal
;
i
++
)
if
(
mask
[
i
]
&
groupbit
)
{
dx
=
x
[
i
][
0
]
-
xc
;
dy
=
x
[
i
][
1
]
-
yc
;
dz
=
x
[
i
][
2
]
-
zc
;
if
(
!
xflag
)
dx
=
0.0
;
if
(
!
yflag
)
dy
=
0.0
;
if
(
!
zflag
)
dz
=
0.0
;
domain
->
minimum_image
(
&
dx
,
&
dy
,
&
dz
);
r
=
sqrt
(
dx
*
dx
+
dy
*
dy
+
dz
*
dz
);
if
(
r
>
delta
)
{
prefactor
=
f_mag
/
r
;
f
[
i
][
0
]
-=
prefactor
*
dx
;
f
[
i
][
1
]
-=
prefactor
*
dy
;
f
[
i
][
2
]
-=
prefactor
*
dz
;
}
}
}
/* ---------------------------------------------------------------------- */
void
FixDrag
::
post_force_respa
(
int
vflag
,
int
ilevel
,
int
iloop
)
{
if
(
ilevel
==
nlevels_respa
-
1
)
post_force
(
vflag
);
}
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