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rLAMMPS lammps
fix_gravity.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 <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "fix_gravity.h"
#include "atom.h"
#include "update.h"
#include "domain.h"
#include "respa.h"
#include "modify.h"
#include "input.h"
#include "variable.h"
#include "math_const.h"
#include "error.h"
#include "force.h"
using
namespace
LAMMPS_NS
;
using
namespace
FixConst
;
using
namespace
MathConst
;
enum
{
CHUTE
,
SPHERICAL
,
VECTOR
};
enum
{
CONSTANT
,
EQUAL
};
/* ---------------------------------------------------------------------- */
FixGravity
::
FixGravity
(
LAMMPS
*
lmp
,
int
narg
,
char
**
arg
)
:
Fix
(
lmp
,
narg
,
arg
),
mstr
(
NULL
),
vstr
(
NULL
),
pstr
(
NULL
),
tstr
(
NULL
),
xstr
(
NULL
),
ystr
(
NULL
),
zstr
(
NULL
)
{
if
(
narg
<
5
)
error
->
all
(
FLERR
,
"Illegal fix gravity command"
);
dynamic_group_allow
=
1
;
scalar_flag
=
1
;
global_freq
=
1
;
extscalar
=
1
;
respa_level_support
=
1
;
ilevel_respa
=
0
;
mstr
=
vstr
=
pstr
=
tstr
=
xstr
=
ystr
=
zstr
=
NULL
;
mstyle
=
vstyle
=
pstyle
=
tstyle
=
xstyle
=
ystyle
=
zstyle
=
CONSTANT
;
if
(
strstr
(
arg
[
3
],
"v_"
)
==
arg
[
3
])
{
int
n
=
strlen
(
&
arg
[
3
][
2
])
+
1
;
mstr
=
new
char
[
n
];
strcpy
(
mstr
,
&
arg
[
3
][
2
]);
mstyle
=
EQUAL
;
}
else
{
magnitude
=
force
->
numeric
(
FLERR
,
arg
[
3
]);
mstyle
=
CONSTANT
;
}
if
(
strcmp
(
arg
[
4
],
"chute"
)
==
0
)
{
if
(
narg
!=
6
)
error
->
all
(
FLERR
,
"Illegal fix gravity command"
);
style
=
CHUTE
;
if
(
strstr
(
arg
[
5
],
"v_"
)
==
arg
[
5
])
{
int
n
=
strlen
(
&
arg
[
5
][
2
])
+
1
;
vstr
=
new
char
[
n
];
strcpy
(
vstr
,
&
arg
[
5
][
2
]);
vstyle
=
EQUAL
;
}
else
{
vert
=
force
->
numeric
(
FLERR
,
arg
[
5
]);
vstyle
=
CONSTANT
;
}
}
else
if
(
strcmp
(
arg
[
4
],
"spherical"
)
==
0
)
{
if
(
narg
!=
7
)
error
->
all
(
FLERR
,
"Illegal fix gravity command"
);
style
=
SPHERICAL
;
if
(
strstr
(
arg
[
5
],
"v_"
)
==
arg
[
5
])
{
int
n
=
strlen
(
&
arg
[
5
][
2
])
+
1
;
pstr
=
new
char
[
n
];
strcpy
(
pstr
,
&
arg
[
5
][
2
]);
pstyle
=
EQUAL
;
}
else
{
phi
=
force
->
numeric
(
FLERR
,
arg
[
5
]);
pstyle
=
CONSTANT
;
}
if
(
strstr
(
arg
[
6
],
"v_"
)
==
arg
[
6
])
{
int
n
=
strlen
(
&
arg
[
6
][
2
])
+
1
;
tstr
=
new
char
[
n
];
strcpy
(
tstr
,
&
arg
[
6
][
2
]);
tstyle
=
EQUAL
;
}
else
{
theta
=
force
->
numeric
(
FLERR
,
arg
[
6
]);
tstyle
=
CONSTANT
;
}
}
else
if
(
strcmp
(
arg
[
4
],
"vector"
)
==
0
)
{
if
(
narg
!=
8
)
error
->
all
(
FLERR
,
"Illegal fix gravity command"
);
style
=
VECTOR
;
if
(
strstr
(
arg
[
5
],
"v_"
)
==
arg
[
5
])
{
int
n
=
strlen
(
&
arg
[
5
][
2
])
+
1
;
xstr
=
new
char
[
n
];
strcpy
(
xstr
,
&
arg
[
5
][
2
]);
xstyle
=
EQUAL
;
}
else
{
xdir
=
force
->
numeric
(
FLERR
,
arg
[
5
]);
xstyle
=
CONSTANT
;
}
if
(
strstr
(
arg
[
6
],
"v_"
)
==
arg
[
6
])
{
int
n
=
strlen
(
&
arg
[
6
][
2
])
+
1
;
ystr
=
new
char
[
n
];
strcpy
(
ystr
,
&
arg
[
6
][
2
]);
ystyle
=
EQUAL
;
}
else
{
ydir
=
force
->
numeric
(
FLERR
,
arg
[
6
]);
ystyle
=
CONSTANT
;
}
if
(
strstr
(
arg
[
7
],
"v_"
)
==
arg
[
7
])
{
int
n
=
strlen
(
&
arg
[
7
][
2
])
+
1
;
zstr
=
new
char
[
n
];
strcpy
(
zstr
,
&
arg
[
7
][
2
]);
zstyle
=
EQUAL
;
}
else
{
zdir
=
force
->
numeric
(
FLERR
,
arg
[
7
]);
zstyle
=
CONSTANT
;
}
}
else
error
->
all
(
FLERR
,
"Illegal fix gravity command"
);
degree2rad
=
MY_PI
/
180.0
;
time_origin
=
update
->
ntimestep
;
eflag
=
0
;
egrav
=
0.0
;
}
/* ---------------------------------------------------------------------- */
FixGravity
::~
FixGravity
()
{
delete
[]
mstr
;
delete
[]
vstr
;
delete
[]
pstr
;
delete
[]
tstr
;
delete
[]
xstr
;
delete
[]
ystr
;
delete
[]
zstr
;
}
/* ---------------------------------------------------------------------- */
int
FixGravity
::
setmask
()
{
int
mask
=
0
;
mask
|=
POST_FORCE
;
mask
|=
THERMO_ENERGY
;
mask
|=
POST_FORCE_RESPA
;
return
mask
;
}
/* ---------------------------------------------------------------------- */
void
FixGravity
::
init
()
{
if
(
strstr
(
update
->
integrate_style
,
"respa"
))
{
ilevel_respa
=
((
Respa
*
)
update
->
integrate
)
->
nlevels
-
1
;
if
(
respa_level
>=
0
)
ilevel_respa
=
MIN
(
respa_level
,
ilevel_respa
);
}
// check variables
if
(
mstr
)
{
mvar
=
input
->
variable
->
find
(
mstr
);
if
(
mvar
<
0
)
error
->
all
(
FLERR
,
"Variable name for fix gravity does not exist"
);
if
(
!
input
->
variable
->
equalstyle
(
mvar
))
error
->
all
(
FLERR
,
"Variable for fix gravity is invalid style"
);
}
if
(
vstr
)
{
vvar
=
input
->
variable
->
find
(
vstr
);
if
(
vvar
<
0
)
error
->
all
(
FLERR
,
"Variable name for fix gravity does not exist"
);
if
(
!
input
->
variable
->
equalstyle
(
vvar
))
error
->
all
(
FLERR
,
"Variable for fix gravity is invalid style"
);
}
if
(
pstr
)
{
pvar
=
input
->
variable
->
find
(
pstr
);
if
(
pvar
<
0
)
error
->
all
(
FLERR
,
"Variable name for fix gravity does not exist"
);
if
(
!
input
->
variable
->
equalstyle
(
pvar
))
error
->
all
(
FLERR
,
"Variable for fix gravity is invalid style"
);
}
if
(
tstr
)
{
tvar
=
input
->
variable
->
find
(
tstr
);
if
(
tvar
<
0
)
error
->
all
(
FLERR
,
"Variable name for fix gravity does not exist"
);
if
(
!
input
->
variable
->
equalstyle
(
tvar
))
error
->
all
(
FLERR
,
"Variable for fix gravity is invalid style"
);
}
if
(
xstr
)
{
xvar
=
input
->
variable
->
find
(
xstr
);
if
(
xvar
<
0
)
error
->
all
(
FLERR
,
"Variable name for fix gravity does not exist"
);
if
(
!
input
->
variable
->
equalstyle
(
xvar
))
error
->
all
(
FLERR
,
"Variable for fix gravity is invalid style"
);
}
if
(
ystr
)
{
yvar
=
input
->
variable
->
find
(
ystr
);
if
(
yvar
<
0
)
error
->
all
(
FLERR
,
"Variable name for fix gravity does not exist"
);
if
(
!
input
->
variable
->
equalstyle
(
yvar
))
error
->
all
(
FLERR
,
"Variable for fix gravity is invalid style"
);
}
if
(
zstr
)
{
zvar
=
input
->
variable
->
find
(
zstr
);
if
(
zvar
<
0
)
error
->
all
(
FLERR
,
"Variable name for fix gravity does not exist"
);
if
(
!
input
->
variable
->
equalstyle
(
zvar
))
error
->
all
(
FLERR
,
"Variable for fix gravity is invalid style"
);
}
varflag
=
CONSTANT
;
if
(
mstyle
!=
CONSTANT
||
vstyle
!=
CONSTANT
||
pstyle
!=
CONSTANT
||
tstyle
!=
CONSTANT
||
xstyle
!=
CONSTANT
||
ystyle
!=
CONSTANT
||
zstyle
!=
CONSTANT
)
varflag
=
EQUAL
;
// set gravity components once and for all
if
(
varflag
==
CONSTANT
)
set_acceleration
();
}
/* ---------------------------------------------------------------------- */
void
FixGravity
::
setup
(
int
vflag
)
{
if
(
strstr
(
update
->
integrate_style
,
"verlet"
))
post_force
(
vflag
);
else
{
((
Respa
*
)
update
->
integrate
)
->
copy_flevel_f
(
ilevel_respa
);
post_force_respa
(
vflag
,
ilevel_respa
,
0
);
((
Respa
*
)
update
->
integrate
)
->
copy_f_flevel
(
ilevel_respa
);
}
}
/* ---------------------------------------------------------------------- */
void
FixGravity
::
post_force
(
int
vflag
)
{
// update gravity due to variables
if
(
varflag
!=
CONSTANT
)
{
modify
->
clearstep_compute
();
if
(
mstyle
==
EQUAL
)
magnitude
=
input
->
variable
->
compute_equal
(
mvar
);
if
(
vstyle
==
EQUAL
)
vert
=
input
->
variable
->
compute_equal
(
vvar
);
if
(
pstyle
==
EQUAL
)
phi
=
input
->
variable
->
compute_equal
(
pvar
);
if
(
tstyle
==
EQUAL
)
theta
=
input
->
variable
->
compute_equal
(
tvar
);
if
(
xstyle
==
EQUAL
)
xdir
=
input
->
variable
->
compute_equal
(
xvar
);
if
(
ystyle
==
EQUAL
)
ydir
=
input
->
variable
->
compute_equal
(
yvar
);
if
(
zstyle
==
EQUAL
)
zdir
=
input
->
variable
->
compute_equal
(
zvar
);
modify
->
addstep_compute
(
update
->
ntimestep
+
1
);
set_acceleration
();
}
double
**
x
=
atom
->
x
;
double
**
f
=
atom
->
f
;
double
*
rmass
=
atom
->
rmass
;
double
*
mass
=
atom
->
mass
;
int
*
mask
=
atom
->
mask
;
int
*
type
=
atom
->
type
;
int
nlocal
=
atom
->
nlocal
;
double
massone
;
eflag
=
0
;
egrav
=
0.0
;
if
(
rmass
)
{
for
(
int
i
=
0
;
i
<
nlocal
;
i
++
)
if
(
mask
[
i
]
&
groupbit
)
{
massone
=
rmass
[
i
];
f
[
i
][
0
]
+=
massone
*
xacc
;
f
[
i
][
1
]
+=
massone
*
yacc
;
f
[
i
][
2
]
+=
massone
*
zacc
;
egrav
-=
massone
*
(
xacc
*
x
[
i
][
0
]
+
yacc
*
x
[
i
][
1
]
+
zacc
*
x
[
i
][
2
]);
}
}
else
{
for
(
int
i
=
0
;
i
<
nlocal
;
i
++
)
if
(
mask
[
i
]
&
groupbit
)
{
massone
=
mass
[
type
[
i
]];
f
[
i
][
0
]
+=
massone
*
xacc
;
f
[
i
][
1
]
+=
massone
*
yacc
;
f
[
i
][
2
]
+=
massone
*
zacc
;
egrav
-=
massone
*
(
xacc
*
x
[
i
][
0
]
+
yacc
*
x
[
i
][
1
]
+
zacc
*
x
[
i
][
2
]);
}
}
}
/* ---------------------------------------------------------------------- */
void
FixGravity
::
post_force_respa
(
int
vflag
,
int
ilevel
,
int
iloop
)
{
if
(
ilevel
==
ilevel_respa
)
post_force
(
vflag
);
}
/* ---------------------------------------------------------------------- */
void
FixGravity
::
set_acceleration
()
{
if
(
style
==
CHUTE
||
style
==
SPHERICAL
)
{
if
(
style
==
CHUTE
)
{
phi
=
0.0
;
theta
=
180.0
-
vert
;
}
if
(
domain
->
dimension
==
3
)
{
xgrav
=
sin
(
degree2rad
*
theta
)
*
cos
(
degree2rad
*
phi
);
ygrav
=
sin
(
degree2rad
*
theta
)
*
sin
(
degree2rad
*
phi
);
zgrav
=
cos
(
degree2rad
*
theta
);
}
else
{
xgrav
=
sin
(
degree2rad
*
theta
);
ygrav
=
cos
(
degree2rad
*
theta
);
zgrav
=
0.0
;
}
}
else
if
(
style
==
VECTOR
)
{
if
(
domain
->
dimension
==
3
)
{
double
length
=
sqrt
(
xdir
*
xdir
+
ydir
*
ydir
+
zdir
*
zdir
);
xgrav
=
xdir
/
length
;
ygrav
=
ydir
/
length
;
zgrav
=
zdir
/
length
;
}
else
{
double
length
=
sqrt
(
xdir
*
xdir
+
ydir
*
ydir
);
xgrav
=
xdir
/
length
;
ygrav
=
ydir
/
length
;
zgrav
=
0.0
;
}
}
xacc
=
magnitude
*
xgrav
;
yacc
=
magnitude
*
ygrav
;
zacc
=
magnitude
*
zgrav
;
}
/* ----------------------------------------------------------------------
potential energy in gravity field
------------------------------------------------------------------------- */
double
FixGravity
::
compute_scalar
()
{
// only sum across procs one time
if
(
eflag
==
0
)
{
MPI_Allreduce
(
&
egrav
,
&
egrav_all
,
1
,
MPI_DOUBLE
,
MPI_SUM
,
world
);
eflag
=
1
;
}
return
egrav_all
;
}
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