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rLAMMPS lammps
fix_wall_piston.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 <string.h>
#include <stdlib.h>
#include "fix_wall_piston.h"
#include "atom.h"
#include "modify.h"
#include "domain.h"
#include "lattice.h"
#include "update.h"
#include "error.h"
#include "random_mars.h"
#include "force.h"
#include "comm.h"
#include "math_const.h"
using
namespace
LAMMPS_NS
;
using
namespace
FixConst
;
using
namespace
MathConst
;
/* ---------------------------------------------------------------------- */
FixWallPiston
::
FixWallPiston
(
LAMMPS
*
lmp
,
int
narg
,
char
**
arg
)
:
Fix
(
lmp
,
narg
,
arg
),
randomt
(
NULL
),
gfactor1
(
NULL
),
gfactor2
(
NULL
)
{
force_reneighbor
=
1
;
next_reneighbor
=
-
1
;
if
(
narg
<
4
)
error
->
all
(
FLERR
,
"Illegal fix wall/piston command"
);
randomt
=
NULL
;
gfactor1
=
gfactor2
=
NULL
;
tempflag
=
0
;
scaleflag
=
1
;
roughflag
=
0
;
rampflag
=
0
;
rampNL1flag
=
0
;
rampNL2flag
=
0
;
rampNL3flag
=
0
;
rampNL4flag
=
0
;
rampNL5flag
=
0
;
t_target
=
z0
=
vx
=
vy
=
vz
=
0.0
;
xloflag
=
xhiflag
=
yloflag
=
yhiflag
=
zloflag
=
zhiflag
=
0
;
int
iarg
=
3
;
while
(
iarg
<
narg
)
{
if
(
strcmp
(
arg
[
iarg
],
"xlo"
)
==
0
)
error
->
all
(
FLERR
,
"Fix wall/piston command only available at zlo"
);
else
if
(
strcmp
(
arg
[
iarg
],
"ylo"
)
==
0
)
error
->
all
(
FLERR
,
"Fix wall/piston command only available at zlo"
);
else
if
(
strcmp
(
arg
[
iarg
],
"zlo"
)
==
0
)
{
zloflag
=
1
;
iarg
++
;
if
(
domain
->
boundary
[
2
][
0
]
!=
2
)
error
->
all
(
FLERR
,
"Must shrink-wrap piston boundary"
);
}
else
if
(
strcmp
(
arg
[
iarg
],
"xhi"
)
==
0
)
error
->
all
(
FLERR
,
"Fix wall/piston command only available at zlo"
);
else
if
(
strcmp
(
arg
[
iarg
],
"yhi"
)
==
0
)
error
->
all
(
FLERR
,
"Fix wall/piston command only available at zlo"
);
else
if
(
strcmp
(
arg
[
iarg
],
"zhi"
)
==
0
)
error
->
all
(
FLERR
,
"Fix wall/piston command only available at zlo"
);
else
if
(
strcmp
(
arg
[
iarg
],
"vel"
)
==
0
)
{
if
(
iarg
+
2
>
narg
)
error
->
all
(
FLERR
,
"Illegal fix wall/piston command"
);
vz
=
force
->
numeric
(
FLERR
,
arg
[
iarg
+
1
]);
iarg
+=
2
;
}
else
if
(
strcmp
(
arg
[
iarg
],
"pos"
)
==
0
)
{
if
(
iarg
+
2
>
narg
)
error
->
all
(
FLERR
,
"Illegal fix wall/piston command"
);
z0
=
force
->
numeric
(
FLERR
,
arg
[
iarg
+
1
]);
iarg
+=
2
;
}
else
if
(
strcmp
(
arg
[
iarg
],
"temp"
)
==
0
)
{
if
(
iarg
+
5
>
narg
)
error
->
all
(
FLERR
,
"Illegal fix wall/piston command"
);
tempflag
=
1
;
t_target
=
force
->
numeric
(
FLERR
,
arg
[
iarg
+
1
]);
t_period
=
force
->
numeric
(
FLERR
,
arg
[
iarg
+
2
]);
tseed
=
force
->
inumeric
(
FLERR
,
arg
[
iarg
+
3
]);
t_extent
=
force
->
numeric
(
FLERR
,
arg
[
iarg
+
4
]);
if
(
t_target
<=
0
)
error
->
all
(
FLERR
,
"Illegal fix wall/piston command"
);
if
(
t_period
<=
0
)
error
->
all
(
FLERR
,
"Illegal fix wall/piston command"
);
if
(
t_extent
<=
0
)
error
->
all
(
FLERR
,
"Illegal fix wall/piston command"
);
if
(
tseed
<=
0
)
error
->
all
(
FLERR
,
"Illegal fix wall/piston command"
);
randomt
=
new
RanMars
(
lmp
,
tseed
+
comm
->
me
);
gfactor1
=
new
double
[
atom
->
ntypes
+
1
];
gfactor2
=
new
double
[
atom
->
ntypes
+
1
];
iarg
+=
5
;
}
else
if
(
strcmp
(
arg
[
iarg
],
"rough"
)
==
0
)
{
roughflag
=
1
;
roughdist
=
force
->
numeric
(
FLERR
,
arg
[
iarg
+
1
]);
iarg
+=
2
;
}
else
if
(
strcmp
(
arg
[
iarg
],
"ramp"
)
==
0
)
{
rampflag
=
1
;
iarg
++
;
}
else
if
(
strcmp
(
arg
[
iarg
],
"rampNL1"
)
==
0
)
{
rampNL1flag
=
1
;
iarg
++
;
}
else
if
(
strcmp
(
arg
[
iarg
],
"rampNL2"
)
==
0
)
{
rampNL2flag
=
1
;
iarg
++
;
}
else
if
(
strcmp
(
arg
[
iarg
],
"rampNL3"
)
==
0
)
{
rampNL3flag
=
1
;
iarg
++
;
}
else
if
(
strcmp
(
arg
[
iarg
],
"rampNL4"
)
==
0
)
{
rampNL4flag
=
1
;
iarg
++
;
}
else
if
(
strcmp
(
arg
[
iarg
],
"rampNL5"
)
==
0
)
{
rampNL5flag
=
1
;
iarg
++
;
}
else
if
(
strcmp
(
arg
[
iarg
],
"units"
)
==
0
)
{
if
(
iarg
+
2
>
narg
)
error
->
all
(
FLERR
,
"Illegal fix wall/piston command"
);
if
(
strcmp
(
arg
[
iarg
+
1
],
"box"
)
==
0
)
scaleflag
=
0
;
else
if
(
strcmp
(
arg
[
iarg
+
1
],
"lattice"
)
==
0
)
scaleflag
=
1
;
else
error
->
all
(
FLERR
,
"Illegal fix wall/piston command"
);
iarg
+=
2
;
}
else
error
->
all
(
FLERR
,
"Illegal fix wall/piston command"
);
}
if
(
vx
<
0.0
||
vy
<
0.0
||
vz
<
0.0
)
error
->
all
(
FLERR
,
"Illegal fix wall/piston velocity"
);
if
((
xloflag
||
xhiflag
)
&&
domain
->
xperiodic
)
error
->
all
(
FLERR
,
"Cannot use wall in periodic dimension"
);
if
((
yloflag
||
yhiflag
)
&&
domain
->
yperiodic
)
error
->
all
(
FLERR
,
"Cannot use wall in periodic dimension"
);
if
((
zloflag
||
zhiflag
)
&&
domain
->
zperiodic
)
error
->
all
(
FLERR
,
"Cannot use wall in periodic dimension"
);
// setup scaling
const
double
zscale
=
(
scaleflag
)
?
domain
->
lattice
->
zlattice
:
1.0
;
vz
*=
zscale
;
z0
*=
zscale
;
roughdist
*=
zscale
;
if
(
rampflag
||
rampNL1flag
||
rampNL2flag
||
rampNL3flag
||
rampNL4flag
||
rampNL5flag
)
{
maxvx
=
vx
;
maxvy
=
vy
;
maxvz
=
vz
;
}
}
/* ---------------------------------------------------------------------- */
FixWallPiston
::~
FixWallPiston
()
{
delete
[]
gfactor2
;
delete
[]
gfactor1
;
delete
randomt
;
}
/* ---------------------------------------------------------------------- */
int
FixWallPiston
::
setmask
()
{
int
mask
=
0
;
mask
|=
INITIAL_INTEGRATE
;
mask
|=
POST_INTEGRATE
;
mask
|=
POST_INTEGRATE_RESPA
;
return
mask
;
}
/* ---------------------------------------------------------------------- */
void
FixWallPiston
::
initial_integrate
(
int
vflag
)
{
next_reneighbor
=
update
->
ntimestep
;
}
/* ---------------------------------------------------------------------- */
void
FixWallPiston
::
post_integrate
()
{
double
zlo
;
double
**
x
=
atom
->
x
;
double
**
v
=
atom
->
v
;
int
*
mask
=
atom
->
mask
;
int
nlocal
=
atom
->
nlocal
;
double
t
=
(
update
->
ntimestep
-
update
->
beginstep
)
*
update
->
dt
;
double
tott
=
(
update
->
endstep
-
update
->
beginstep
)
*
update
->
dt
;
double
tt
=
t
*
t
;
double
ttt
=
tt
*
t
;
double
tttt
=
tt
*
tt
;
double
t0p5
=
sqrt
(
t
/
tott
);
double
t1p5
=
t0p5
*
t0p5
*
t0p5
;
double
t2p5
=
t1p5
*
t0p5
*
t0p5
;
if
(
rampflag
)
{
paccelx
=
maxvx
/
tott
;
paccely
=
maxvy
/
tott
;
paccelz
=
maxvz
/
tott
;
if
(
zloflag
)
{
zlo
=
z0
+
0.5
*
paccelz
*
tt
;
vz
=
paccelz
*
t
;
}
}
else
if
(
rampNL1flag
)
{
paccelz
=
maxvz
/
tott
;
angfreq
=
MY_2PI
/
(
0.5
*
tott
);
if
(
zloflag
)
{
zlo
=
z0
+
paccelz
*
(
0.5
*
tt
+
1.0
/
(
angfreq
*
angfreq
)
-
1.0
/
(
angfreq
*
angfreq
)
*
cos
(
angfreq
*
t
));
vz
=
paccelz
*
(
t
+
1.0
/
angfreq
*
sin
(
angfreq
*
t
));
}
else
error
->
all
(
FLERR
,
"NL ramp in wall/piston only implemented in zlo for now"
);
}
else
if
(
rampNL2flag
)
{
paccelz
=
maxvz
/
tott
;
angfreq
=
3.0
*
MY_2PI
/
tott
;
if
(
zloflag
)
{
zlo
=
z0
+
paccelz
*
(
0.5
*
tt
+
4.0
/
(
3.0
*
angfreq
*
angfreq
)
*
(
1.0
-
cos
(
angfreq
*
t
))
+
1.0
/
(
6.0
*
angfreq
*
angfreq
)
*
(
1.0
-
cos
(
2.0
*
angfreq
*
t
)));
vz
=
paccelz
*
(
t
+
4.0
/
(
3.0
*
angfreq
)
*
sin
(
angfreq
*
t
)
+
1.0
/
(
3.0
*
angfreq
)
*
sin
(
2.0
*
angfreq
*
t
));
}
else
error
->
all
(
FLERR
,
"NL ramp in wall/piston only implemented in zlo for now"
);
}
else
if
(
rampNL3flag
)
{
paccelz
=
maxvz
/
tott
;
if
(
zloflag
)
{
zlo
=
z0
+
paccelz
*
tott
*
tott
/
2.5
*
(
t2p5
);
vz
=
paccelz
*
tott
*
(
t1p5
);
}
else
error
->
all
(
FLERR
,
"NL ramp in wall/piston only implemented in zlo for now"
);
}
else
if
(
rampNL4flag
)
{
paccelz
=
maxvz
/
tott
;
if
(
zloflag
)
{
zlo
=
z0
+
paccelz
/
tott
/
3.0
*
(
ttt
);
vz
=
paccelz
/
tott
*
(
tt
);
}
else
error
->
all
(
FLERR
,
"NL ramp in wall/piston only implemented in zlo for now"
);
}
else
if
(
rampNL5flag
)
{
paccelz
=
maxvz
/
tott
;
if
(
zloflag
)
{
zlo
=
z0
+
paccelz
/
tott
/
tott
/
4.0
*
(
tttt
);
vz
=
paccelz
/
tott
/
tott
*
(
ttt
);
}
else
error
->
all
(
FLERR
,
"NL ramp in wall/piston only implemented in zlo for now"
);
}
else
{
if
(
zloflag
)
{
zlo
=
z0
+
vz
*
t
;
}
}
if
(
update
->
ntimestep
%
1000
==
0
)
if
(
comm
->
me
==
0
)
{
if
(
screen
)
fprintf
(
screen
,
"SHOCK: step "
BIGINT_FORMAT
" t %g zpos %g vz %g az %g zlo %g
\n
"
,
update
->
ntimestep
,
t
,
zlo
,
vz
,
paccelz
,
domain
->
boxlo
[
2
]);
if
(
logfile
)
fprintf
(
logfile
,
"SHOCK: step "
BIGINT_FORMAT
" t %g zpos %g vz %g az %g zlo %g
\n
"
,
update
->
ntimestep
,
t
,
zlo
,
vz
,
paccelz
,
domain
->
boxlo
[
2
]);
}
// VIRIAL PRESSURE CONTRIBUTION?
for
(
int
i
=
0
;
i
<
nlocal
;
i
++
)
{
if
(
mask
[
i
]
&
groupbit
)
{
roughoff
=
0.0
;
if
(
roughflag
)
{
roughoff
+=
roughdist
*
fabs
((
x
[
i
][
0
]
-
domain
->
boxlo
[
0
])
/
(
domain
->
boxhi
[
0
]
-
domain
->
boxlo
[
0
])
-
0.5
);
roughoff
+=
roughdist
*
fabs
((
x
[
i
][
1
]
-
domain
->
boxlo
[
1
])
/
(
domain
->
boxhi
[
1
]
-
domain
->
boxlo
[
1
])
-
0.5
);
}
if
(
zloflag
&&
x
[
i
][
2
]
<
zlo
-
roughoff
)
{
x
[
i
][
2
]
=
2.0
*
(
zlo
-
roughoff
)
-
x
[
i
][
2
];
v
[
i
][
2
]
=
2.0
*
vz
-
v
[
i
][
2
];
}
}
}
double
**
f
=
atom
->
f
;
int
*
type
=
atom
->
type
;
double
gamma1
,
gamma2
;
double
tsqrt
=
sqrt
(
t_target
);
if
(
atom
->
mass
)
{
if
(
tempflag
)
{
for
(
int
i
=
1
;
i
<=
atom
->
ntypes
;
i
++
)
{
gfactor1
[
i
]
=
-
atom
->
mass
[
i
]
/
t_period
/
force
->
ftm2v
;
gfactor2
[
i
]
=
sqrt
(
atom
->
mass
[
i
])
*
sqrt
(
24.0
*
force
->
boltz
/
t_period
/
update
->
dt
/
force
->
mvv2e
)
/
force
->
ftm2v
;
}
}
for
(
int
i
=
0
;
i
<
nlocal
;
i
++
)
{
// SET TEMP AHEAD OF PISTON
if
(
tempflag
&&
x
[
i
][
2
]
<=
domain
->
boxlo
[
2
]
+
t_extent
)
{
gamma1
=
gfactor1
[
type
[
i
]];
gamma2
=
gfactor2
[
type
[
i
]]
*
tsqrt
;
f
[
i
][
0
]
+=
gamma1
*
v
[
i
][
0
]
+
gamma2
*
(
randomt
->
uniform
()
-
0.5
);
f
[
i
][
1
]
+=
gamma1
*
v
[
i
][
1
]
+
gamma2
*
(
randomt
->
uniform
()
-
0.5
);
f
[
i
][
2
]
+=
gamma1
*
(
v
[
i
][
2
]
-
vz
)
+
gamma2
*
(
randomt
->
uniform
()
-
0.5
);
}
}
}
else
{
double
*
rmass
=
atom
->
rmass
;
double
boltz
=
force
->
boltz
;
double
dt
=
update
->
dt
;
double
mvv2e
=
force
->
mvv2e
;
double
ftm2v
=
force
->
ftm2v
;
for
(
int
i
=
0
;
i
<
nlocal
;
i
++
)
{
// SET TEMP AHEAD OF PISTON
if
(
tempflag
&&
x
[
i
][
2
]
<=
domain
->
boxlo
[
2
]
+
t_extent
)
{
gamma1
=
-
rmass
[
i
]
/
t_period
/
ftm2v
;
gamma2
=
sqrt
(
rmass
[
i
])
*
sqrt
(
24.0
*
boltz
/
t_period
/
dt
/
mvv2e
)
/
ftm2v
;
gamma2
*=
tsqrt
;
f
[
i
][
0
]
+=
gamma1
*
v
[
i
][
0
]
+
gamma2
*
(
randomt
->
uniform
()
-
0.5
);
f
[
i
][
1
]
+=
gamma1
*
v
[
i
][
1
]
+
gamma2
*
(
randomt
->
uniform
()
-
0.5
);
f
[
i
][
2
]
+=
gamma1
*
v
[
i
][
2
]
+
gamma2
*
(
randomt
->
uniform
()
-
0.5
);
}
}
}
}
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