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fix_ti_rs.cpp
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Tue, Oct 8, 07:04
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rLAMMPS lammps
fix_ti_rs.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.
------------------------------------------------------------------------- */
/* -------------------------------------------------------------------------
Contributing authors:
Rodrigo Freitas (Unicamp/Brazil) - rodrigohb@gmail.com
Maurice de Koning (Unicamp/Brazil) - dekoning@ifi.unicamp.br
------------------------------------------------------------------------- */
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include "fix_ti_rs.h"
#include "atom.h"
#include "update.h"
#include "respa.h"
#include "error.h"
#include "force.h"
using
namespace
LAMMPS_NS
;
using
namespace
FixConst
;
/* ---------------------------------------------------------------------- */
// Class constructor initialize all variables.
FixTIRS
::
FixTIRS
(
LAMMPS
*
lmp
,
int
narg
,
char
**
arg
)
:
Fix
(
lmp
,
narg
,
arg
)
{
// Checking the input information.
if
(
narg
<
7
||
narg
>
9
)
error
->
all
(
FLERR
,
"Illegal fix ti/rs command"
);
// Fix flags.
vector_flag
=
1
;
size_vector
=
2
;
global_freq
=
1
;
extvector
=
1
;
// Time variables.
t_switch
=
force
->
bnumeric
(
FLERR
,
arg
[
5
]);
t_equil
=
force
->
bnumeric
(
FLERR
,
arg
[
6
]);
t0
=
update
->
ntimestep
;
if
(
t_switch
<=
0
)
error
->
all
(
FLERR
,
"Illegal fix ti/rs command"
);
if
(
t_equil
<=
0
)
error
->
all
(
FLERR
,
"Illegal fix ti/rs command"
);
// Coupling parameter limits and initialization.
l_initial
=
force
->
numeric
(
FLERR
,
arg
[
3
]);
l_final
=
force
->
numeric
(
FLERR
,
arg
[
4
]);
sf
=
1
;
if
(
narg
>
7
)
{
if
(
strcmp
(
arg
[
7
],
"function"
)
==
0
)
sf
=
force
->
inumeric
(
FLERR
,
arg
[
8
]);
else
error
->
all
(
FLERR
,
"Illegal fix ti/rs switching function"
);
if
((
sf
<
1
)
||
(
sf
>
3
))
error
->
all
(
FLERR
,
"Illegal fix ti/rs switching function"
);
}
lambda
=
switch_func
(
0
);
dlambda
=
dswitch_func
(
0
);
}
/* ---------------------------------------------------------------------- */
FixTIRS
::~
FixTIRS
()
{
// unregister callbacks to this fix from Atom class
atom
->
delete_callback
(
id
,
0
);
atom
->
delete_callback
(
id
,
1
);
}
/* ---------------------------------------------------------------------- */
int
FixTIRS
::
setmask
()
{
int
mask
=
0
;
mask
|=
INITIAL_INTEGRATE
;
mask
|=
POST_FORCE
;
return
mask
;
}
/* ---------------------------------------------------------------------- */
void
FixTIRS
::
init
()
{
if
(
strstr
(
update
->
integrate_style
,
"respa"
))
nlevels_respa
=
((
Respa
*
)
update
->
integrate
)
->
nlevels
;
}
/* ---------------------------------------------------------------------- */
void
FixTIRS
::
setup
(
int
vflag
)
{
if
(
strstr
(
update
->
integrate_style
,
"verlet"
))
post_force
(
vflag
);
else
{
((
Respa
*
)
update
->
integrate
)
->
copy_flevel_f
(
nlevels_respa
-
1
);
post_force_respa
(
vflag
,
nlevels_respa
-
1
,
0
);
((
Respa
*
)
update
->
integrate
)
->
copy_f_flevel
(
nlevels_respa
-
1
);
}
}
/* ---------------------------------------------------------------------- */
void
FixTIRS
::
min_setup
(
int
vflag
)
{
post_force
(
vflag
);
}
/* ---------------------------------------------------------------------- */
void
FixTIRS
::
post_force
(
int
vflag
)
{
int
*
mask
=
atom
->
mask
;
int
nlocal
=
atom
->
nlocal
;
double
**
f
=
atom
->
f
;
// Scaling forces.
for
(
int
i
=
0
;
i
<
nlocal
;
i
++
)
{
if
(
mask
[
i
]
&
groupbit
)
{
f
[
i
][
0
]
=
lambda
*
f
[
i
][
0
];
f
[
i
][
1
]
=
lambda
*
f
[
i
][
1
];
f
[
i
][
2
]
=
lambda
*
f
[
i
][
2
];
}
}
}
/* ---------------------------------------------------------------------- */
void
FixTIRS
::
post_force_respa
(
int
vflag
,
int
ilevel
,
int
iloop
)
{
if
(
ilevel
==
nlevels_respa
-
1
)
post_force
(
vflag
);
}
/* ---------------------------------------------------------------------- */
void
FixTIRS
::
min_post_force
(
int
vflag
)
{
post_force
(
vflag
);
}
/* ---------------------------------------------------------------------- */
void
FixTIRS
::
initial_integrate
(
int
vflag
)
{
// Update the coupling parameter value.
const
bigint
t
=
update
->
ntimestep
-
(
t0
+
t_equil
);
const
double
r_switch
=
1.0
/
t_switch
;
if
(
(
t
>=
0
)
&&
(
t
<=
t_switch
)
)
{
lambda
=
switch_func
(
t
*
r_switch
);
dlambda
=
dswitch_func
(
t
*
r_switch
);
}
if
(
(
t
>=
t_equil
+
t_switch
)
&&
(
t
<=
(
t_equil
+
2
*
t_switch
))
)
{
lambda
=
switch_func
(
1.0
-
(
t
-
t_switch
-
t_equil
)
*
r_switch
);
dlambda
=
-
dswitch_func
(
1.0
-
(
t
-
t_switch
-
t_equil
)
*
r_switch
);
}
}
/* ---------------------------------------------------------------------- */
double
FixTIRS
::
compute_vector
(
int
n
)
{
linfo
[
0
]
=
lambda
;
linfo
[
1
]
=
dlambda
;
return
linfo
[
n
];
}
/* ---------------------------------------------------------------------- */
double
FixTIRS
::
switch_func
(
double
t
)
{
if
(
sf
==
2
)
return
l_initial
/
(
1
+
t
*
(
l_initial
/
l_final
-
1
));
if
(
sf
==
3
)
return
l_initial
/
(
1
+
log2
(
1
+
t
)
*
(
l_initial
/
l_final
-
1
));
// Default option is sf = 1.
return
l_initial
+
(
l_final
-
l_initial
)
*
t
;
}
/* ---------------------------------------------------------------------- */
double
FixTIRS
::
dswitch_func
(
double
t
)
{
double
aux
=
(
1.0
/
l_initial
-
1.0
/
l_final
);
if
(
sf
==
2
)
return
lambda
*
lambda
*
aux
/
t_switch
;
if
(
sf
==
3
)
return
lambda
*
lambda
*
aux
/
(
t_switch
*
log
(
2
)
*
(
1
+
t
));
// Default option is sf = 1.
return
(
l_final
-
l_initial
)
/
t_switch
;
}
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