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pair_lj_cut_opt.cpp
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Fri, Aug 23, 05:07
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text/x-c++
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rLAMMPS lammps
pair_lj_cut_opt.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:
James Fischer, High Performance Technologies, Inc.
David Richie, Stone Ridge Technology
Vincent Natoli, Stone Ridge Technology
------------------------------------------------------------------------- */
#include <stdlib.h>
#include "pair_lj_cut_opt.h"
#include "atom.h"
#include "force.h"
#include "neigh_list.h"
using
namespace
LAMMPS_NS
;
/* ---------------------------------------------------------------------- */
PairLJCutOpt
::
PairLJCutOpt
(
LAMMPS
*
lmp
)
:
PairLJCut
(
lmp
)
{}
/* ---------------------------------------------------------------------- */
void
PairLJCutOpt
::
compute
(
int
eflag
,
int
vflag
)
{
if
(
eflag
||
vflag
)
ev_setup
(
eflag
,
vflag
);
else
evflag
=
vflag_fdotr
=
0
;
if
(
evflag
)
{
if
(
eflag
)
{
if
(
force
->
newton_pair
)
return
eval
<
1
,
1
,
1
>
();
else
return
eval
<
1
,
1
,
0
>
();
}
else
{
if
(
force
->
newton_pair
)
return
eval
<
1
,
0
,
1
>
();
else
return
eval
<
1
,
0
,
0
>
();
}
}
else
{
if
(
force
->
newton_pair
)
return
eval
<
0
,
0
,
1
>
();
else
return
eval
<
0
,
0
,
0
>
();
}
}
/* ---------------------------------------------------------------------- */
template
<
int
EVFLAG
,
int
EFLAG
,
int
NEWTON_PAIR
>
void
PairLJCutOpt
::
eval
()
{
typedef
struct
{
double
x
,
y
,
z
;
}
vec3_t
;
typedef
struct
{
double
cutsq
,
lj1
,
lj2
,
lj3
,
lj4
,
offset
;
double
_pad
[
2
];
}
fast_alpha_t
;
int
i
,
j
,
ii
,
jj
,
inum
,
jnum
,
itype
,
jtype
,
sbindex
;
double
factor_lj
;
double
evdwl
=
0.0
;
double
**
_noalias
x
=
atom
->
x
;
double
**
_noalias
f
=
atom
->
f
;
int
*
_noalias
type
=
atom
->
type
;
int
nlocal
=
atom
->
nlocal
;
double
*
_noalias
special_lj
=
force
->
special_lj
;
inum
=
list
->
inum
;
int
*
_noalias
ilist
=
list
->
ilist
;
int
**
_noalias
firstneigh
=
list
->
firstneigh
;
int
*
_noalias
numneigh
=
list
->
numneigh
;
vec3_t
*
_noalias
xx
=
(
vec3_t
*
)
x
[
0
];
vec3_t
*
_noalias
ff
=
(
vec3_t
*
)
f
[
0
];
int
ntypes
=
atom
->
ntypes
;
int
ntypes2
=
ntypes
*
ntypes
;
fast_alpha_t
*
_noalias
fast_alpha
=
(
fast_alpha_t
*
)
malloc
(
ntypes2
*
sizeof
(
fast_alpha_t
));
for
(
i
=
0
;
i
<
ntypes
;
i
++
)
for
(
j
=
0
;
j
<
ntypes
;
j
++
)
{
fast_alpha_t
&
a
=
fast_alpha
[
i
*
ntypes
+
j
];
a
.
cutsq
=
cutsq
[
i
+
1
][
j
+
1
];
a
.
lj1
=
lj1
[
i
+
1
][
j
+
1
];
a
.
lj2
=
lj2
[
i
+
1
][
j
+
1
];
a
.
lj3
=
lj3
[
i
+
1
][
j
+
1
];
a
.
lj4
=
lj4
[
i
+
1
][
j
+
1
];
a
.
offset
=
offset
[
i
+
1
][
j
+
1
];
}
fast_alpha_t
*
_noalias
tabsix
=
fast_alpha
;
// loop over neighbors of my atoms
for
(
ii
=
0
;
ii
<
inum
;
ii
++
)
{
i
=
ilist
[
ii
];
double
xtmp
=
xx
[
i
].
x
;
double
ytmp
=
xx
[
i
].
y
;
double
ztmp
=
xx
[
i
].
z
;
itype
=
type
[
i
]
-
1
;
int
*
_noalias
jlist
=
firstneigh
[
i
];
jnum
=
numneigh
[
i
];
double
tmpfx
=
0.0
;
double
tmpfy
=
0.0
;
double
tmpfz
=
0.0
;
fast_alpha_t
*
_noalias
tabsixi
=
(
fast_alpha_t
*
)
&
tabsix
[
itype
*
ntypes
];
for
(
jj
=
0
;
jj
<
jnum
;
jj
++
)
{
j
=
jlist
[
jj
];
sbindex
=
sbmask
(
j
);
if
(
sbindex
==
0
)
{
double
delx
=
xtmp
-
xx
[
j
].
x
;
double
dely
=
ytmp
-
xx
[
j
].
y
;
double
delz
=
ztmp
-
xx
[
j
].
z
;
double
rsq
=
delx
*
delx
+
dely
*
dely
+
delz
*
delz
;
jtype
=
type
[
j
]
-
1
;
fast_alpha_t
&
a
=
tabsixi
[
jtype
];
if
(
rsq
<
a
.
cutsq
)
{
double
r2inv
=
1.0
/
rsq
;
double
r6inv
=
r2inv
*
r2inv
*
r2inv
;
double
forcelj
=
r6inv
*
(
a
.
lj1
*
r6inv
-
a
.
lj2
);
double
fpair
=
forcelj
*
r2inv
;
tmpfx
+=
delx
*
fpair
;
tmpfy
+=
dely
*
fpair
;
tmpfz
+=
delz
*
fpair
;
if
(
NEWTON_PAIR
||
j
<
nlocal
)
{
ff
[
j
].
x
-=
delx
*
fpair
;
ff
[
j
].
y
-=
dely
*
fpair
;
ff
[
j
].
z
-=
delz
*
fpair
;
}
if
(
EFLAG
)
evdwl
=
r6inv
*
(
a
.
lj3
*
r6inv
-
a
.
lj4
)
-
a
.
offset
;
if
(
EVFLAG
)
ev_tally
(
i
,
j
,
nlocal
,
NEWTON_PAIR
,
evdwl
,
0.0
,
fpair
,
delx
,
dely
,
delz
);
}
}
else
{
factor_lj
=
special_lj
[
sbindex
];
j
&=
NEIGHMASK
;
double
delx
=
xtmp
-
xx
[
j
].
x
;
double
dely
=
ytmp
-
xx
[
j
].
y
;
double
delz
=
ztmp
-
xx
[
j
].
z
;
double
rsq
=
delx
*
delx
+
dely
*
dely
+
delz
*
delz
;
int
jtype1
=
type
[
j
];
jtype
=
jtype1
-
1
;
fast_alpha_t
&
a
=
tabsixi
[
jtype
];
if
(
rsq
<
a
.
cutsq
)
{
double
r2inv
=
1.0
/
rsq
;
double
r6inv
=
r2inv
*
r2inv
*
r2inv
;
fast_alpha_t
&
a
=
tabsixi
[
jtype
];
double
forcelj
=
r6inv
*
(
a
.
lj1
*
r6inv
-
a
.
lj2
);
double
fpair
=
factor_lj
*
forcelj
*
r2inv
;
tmpfx
+=
delx
*
fpair
;
tmpfy
+=
dely
*
fpair
;
tmpfz
+=
delz
*
fpair
;
if
(
NEWTON_PAIR
||
j
<
nlocal
)
{
ff
[
j
].
x
-=
delx
*
fpair
;
ff
[
j
].
y
-=
dely
*
fpair
;
ff
[
j
].
z
-=
delz
*
fpair
;
}
if
(
EFLAG
)
{
evdwl
=
r6inv
*
(
a
.
lj3
*
r6inv
-
a
.
lj4
)
-
a
.
offset
;
evdwl
*=
factor_lj
;
}
if
(
EVFLAG
)
ev_tally
(
i
,
j
,
nlocal
,
NEWTON_PAIR
,
evdwl
,
0.0
,
fpair
,
delx
,
dely
,
delz
);
}
}
}
ff
[
i
].
x
+=
tmpfx
;
ff
[
i
].
y
+=
tmpfy
;
ff
[
i
].
z
+=
tmpfz
;
}
free
(
fast_alpha
);
fast_alpha
=
0
;
if
(
vflag_fdotr
)
virial_fdotr_compute
();
}
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