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pair_buck_coul_msm.cpp
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Tue, Sep 3, 02:57
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text/x-c
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Thu, Sep 5, 02:57 (2 d)
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rLAMMPS lammps
pair_buck_coul_msm.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 "pair_buck_coul_msm.h"
#include "atom.h"
#include "comm.h"
#include "force.h"
#include "kspace.h"
#include "neighbor.h"
#include "neigh_list.h"
#include "math_const.h"
#include "memory.h"
#include "error.h"
using
namespace
LAMMPS_NS
;
using
namespace
MathConst
;
/* ---------------------------------------------------------------------- */
PairBuckCoulMSM
::
PairBuckCoulMSM
(
LAMMPS
*
lmp
)
:
PairBuckCoulLong
(
lmp
)
{
ewaldflag
=
pppmflag
=
0
;
msmflag
=
1
;
nmax
=
0
;
ftmp
=
NULL
;
}
/* ---------------------------------------------------------------------- */
PairBuckCoulMSM
::~
PairBuckCoulMSM
()
{
if
(
ftmp
)
memory
->
destroy
(
ftmp
);
}
/* ---------------------------------------------------------------------- */
void
PairBuckCoulMSM
::
compute
(
int
eflag
,
int
vflag
)
{
int
i
,
j
,
ii
,
jj
,
inum
,
jnum
,
itype
,
jtype
;
double
qtmp
,
xtmp
,
ytmp
,
ztmp
,
delx
,
dely
,
delz
,
evdwl
,
ecoul
,
fpair
,
fcoul
;
double
rsq
,
r2inv
,
r6inv
,
forcecoul
,
forcebuck
,
factor_coul
,
factor_lj
;
double
egamma
,
fgamma
,
prefactor
;
double
r
,
rexp
;
int
*
ilist
,
*
jlist
,
*
numneigh
,
**
firstneigh
;
int
eflag_old
=
eflag
;
if
(
force
->
kspace
->
scalar_pressure_flag
&&
vflag
)
{
if
(
vflag
>
2
)
error
->
all
(
FLERR
,
"Must use 'kspace_modify pressure/scalar no' "
"to obtain per-atom virial with kspace_style MSM"
);
if
(
atom
->
nmax
>
nmax
)
{
if
(
ftmp
)
memory
->
destroy
(
ftmp
);
nmax
=
atom
->
nmax
;
memory
->
create
(
ftmp
,
nmax
,
3
,
"pair:ftmp"
);
}
memset
(
&
ftmp
[
0
][
0
],
0
,
nmax
*
3
*
sizeof
(
double
));
// must switch on global energy computation if not already on
if
(
eflag
==
0
||
eflag
==
2
)
{
eflag
++
;
}
}
evdwl
=
ecoul
=
0.0
;
if
(
eflag
||
vflag
)
ev_setup
(
eflag
,
vflag
);
else
evflag
=
vflag_fdotr
=
0
;
double
**
x
=
atom
->
x
;
double
**
f
=
atom
->
f
;
double
*
q
=
atom
->
q
;
int
*
type
=
atom
->
type
;
int
nlocal
=
atom
->
nlocal
;
double
*
special_coul
=
force
->
special_coul
;
double
*
special_lj
=
force
->
special_lj
;
int
newton_pair
=
force
->
newton_pair
;
double
qqrd2e
=
force
->
qqrd2e
;
inum
=
list
->
inum
;
ilist
=
list
->
ilist
;
numneigh
=
list
->
numneigh
;
firstneigh
=
list
->
firstneigh
;
// loop over neighbors of my atoms
for
(
ii
=
0
;
ii
<
inum
;
ii
++
)
{
i
=
ilist
[
ii
];
qtmp
=
q
[
i
];
xtmp
=
x
[
i
][
0
];
ytmp
=
x
[
i
][
1
];
ztmp
=
x
[
i
][
2
];
itype
=
type
[
i
];
jlist
=
firstneigh
[
i
];
jnum
=
numneigh
[
i
];
for
(
jj
=
0
;
jj
<
jnum
;
jj
++
)
{
j
=
jlist
[
jj
];
factor_lj
=
special_lj
[
sbmask
(
j
)];
factor_coul
=
special_coul
[
sbmask
(
j
)];
j
&=
NEIGHMASK
;
delx
=
xtmp
-
x
[
j
][
0
];
dely
=
ytmp
-
x
[
j
][
1
];
delz
=
ztmp
-
x
[
j
][
2
];
rsq
=
delx
*
delx
+
dely
*
dely
+
delz
*
delz
;
jtype
=
type
[
j
];
if
(
rsq
<
cutsq
[
itype
][
jtype
])
{
r2inv
=
1.0
/
rsq
;
r
=
sqrt
(
rsq
);
if
(
rsq
<
cut_coulsq
)
{
prefactor
=
qqrd2e
*
qtmp
*
q
[
j
]
/
r
;
egamma
=
1.0
-
(
r
/
cut_coul
)
*
force
->
kspace
->
gamma
(
r
/
cut_coul
);
fgamma
=
1.0
+
(
rsq
/
cut_coulsq
)
*
force
->
kspace
->
dgamma
(
r
/
cut_coul
);
forcecoul
=
prefactor
*
fgamma
;
if
(
factor_coul
<
1.0
)
forcecoul
-=
(
1.0
-
factor_coul
)
*
prefactor
;
}
else
forcecoul
=
0.0
;
if
(
rsq
<
cut_ljsq
[
itype
][
jtype
])
{
r6inv
=
r2inv
*
r2inv
*
r2inv
;
rexp
=
exp
(
-
r
*
rhoinv
[
itype
][
jtype
]);
forcebuck
=
buck1
[
itype
][
jtype
]
*
r
*
rexp
-
buck2
[
itype
][
jtype
]
*
r6inv
;
}
else
forcebuck
=
0.0
;
if
(
!
(
force
->
kspace
->
scalar_pressure_flag
&&
vflag
))
{
fpair
=
(
forcecoul
+
factor_lj
*
forcebuck
)
*
r2inv
;
f
[
i
][
0
]
+=
delx
*
fpair
;
f
[
i
][
1
]
+=
dely
*
fpair
;
f
[
i
][
2
]
+=
delz
*
fpair
;
if
(
newton_pair
||
j
<
nlocal
)
{
f
[
j
][
0
]
-=
delx
*
fpair
;
f
[
j
][
1
]
-=
dely
*
fpair
;
f
[
j
][
2
]
-=
delz
*
fpair
;
}
}
else
{
// separate Buck and Coulombic forces
fpair
=
(
factor_lj
*
forcebuck
)
*
r2inv
;
f
[
i
][
0
]
+=
delx
*
fpair
;
f
[
i
][
1
]
+=
dely
*
fpair
;
f
[
i
][
2
]
+=
delz
*
fpair
;
if
(
newton_pair
||
j
<
nlocal
)
{
f
[
j
][
0
]
-=
delx
*
fpair
;
f
[
j
][
1
]
-=
dely
*
fpair
;
f
[
j
][
2
]
-=
delz
*
fpair
;
}
fcoul
=
(
forcecoul
)
*
r2inv
;
ftmp
[
i
][
0
]
+=
delx
*
fcoul
;
ftmp
[
i
][
1
]
+=
dely
*
fcoul
;
ftmp
[
i
][
2
]
+=
delz
*
fcoul
;
if
(
newton_pair
||
j
<
nlocal
)
{
ftmp
[
j
][
0
]
-=
delx
*
fcoul
;
ftmp
[
j
][
1
]
-=
dely
*
fcoul
;
ftmp
[
j
][
2
]
-=
delz
*
fcoul
;
}
}
if
(
eflag
)
{
if
(
rsq
<
cut_coulsq
)
{
ecoul
=
prefactor
*
egamma
;
if
(
factor_coul
<
1.0
)
ecoul
-=
(
1.0
-
factor_coul
)
*
prefactor
;
}
else
ecoul
=
0.0
;
if
(
eflag_old
&&
rsq
<
cut_ljsq
[
itype
][
jtype
])
{
evdwl
=
a
[
itype
][
jtype
]
*
rexp
-
c
[
itype
][
jtype
]
*
r6inv
-
offset
[
itype
][
jtype
];
evdwl
*=
factor_lj
;
}
else
evdwl
=
0.0
;
}
if
(
evflag
)
ev_tally
(
i
,
j
,
nlocal
,
newton_pair
,
evdwl
,
ecoul
,
fpair
,
delx
,
dely
,
delz
);
}
}
}
if
(
vflag_fdotr
)
virial_fdotr_compute
();
if
(
force
->
kspace
->
scalar_pressure_flag
&&
vflag
)
{
for
(
i
=
0
;
i
<
3
;
i
++
)
virial
[
i
]
+=
force
->
pair
->
eng_coul
/
3.0
;
for
(
int
i
=
0
;
i
<
nmax
;
i
++
)
{
f
[
i
][
0
]
+=
ftmp
[
i
][
0
];
f
[
i
][
1
]
+=
ftmp
[
i
][
1
];
f
[
i
][
2
]
+=
ftmp
[
i
][
2
];
}
}
}
/* ---------------------------------------------------------------------- */
double
PairBuckCoulMSM
::
single
(
int
i
,
int
j
,
int
itype
,
int
jtype
,
double
rsq
,
double
factor_coul
,
double
factor_lj
,
double
&
fforce
)
{
double
r2inv
,
r6inv
,
r
,
rexp
,
egamma
,
fgamma
,
prefactor
;
double
forcecoul
,
forcebuck
,
phicoul
,
phibuck
;
r2inv
=
1.0
/
rsq
;
if
(
rsq
<
cut_coulsq
)
{
r
=
sqrt
(
rsq
);
prefactor
=
force
->
qqrd2e
*
atom
->
q
[
i
]
*
atom
->
q
[
j
]
/
r
;
egamma
=
1.0
-
(
r
/
cut_coul
)
*
force
->
kspace
->
gamma
(
r
/
cut_coul
);
fgamma
=
1.0
+
(
rsq
/
cut_coulsq
)
*
force
->
kspace
->
dgamma
(
r
/
cut_coul
);
forcecoul
=
prefactor
*
fgamma
;
if
(
factor_coul
<
1.0
)
forcecoul
-=
(
1.0
-
factor_coul
)
*
prefactor
;
}
else
forcecoul
=
0.0
;
if
(
rsq
<
cut_ljsq
[
itype
][
jtype
])
{
r6inv
=
r2inv
*
r2inv
*
r2inv
;
r
=
sqrt
(
rsq
);
rexp
=
exp
(
-
r
*
rhoinv
[
itype
][
jtype
]);
forcebuck
=
buck1
[
itype
][
jtype
]
*
r
*
rexp
-
buck2
[
itype
][
jtype
]
*
r6inv
;
}
else
forcebuck
=
0.0
;
fforce
=
(
forcecoul
+
factor_lj
*
forcebuck
)
*
r2inv
;
double
eng
=
0.0
;
if
(
rsq
<
cut_coulsq
)
{
phicoul
=
prefactor
*
egamma
;
if
(
factor_coul
<
1.0
)
phicoul
-=
(
1.0
-
factor_coul
)
*
prefactor
;
eng
+=
phicoul
;
}
if
(
rsq
<
cut_ljsq
[
itype
][
jtype
])
{
phibuck
=
a
[
itype
][
jtype
]
*
rexp
-
c
[
itype
][
jtype
]
*
r6inv
-
offset
[
itype
][
jtype
];
eng
+=
factor_lj
*
phibuck
;
}
return
eng
;
}
/* ---------------------------------------------------------------------- */
void
*
PairBuckCoulMSM
::
extract
(
const
char
*
str
,
int
&
dim
)
{
dim
=
0
;
if
(
strcmp
(
str
,
"cut_coul"
)
==
0
)
return
(
void
*
)
&
cut_coul
;
return
NULL
;
}
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