Page Menu
Home
c4science
Search
Configure Global Search
Log In
Files
F88046775
pair_coul_long_cs.cpp
No One
Temporary
Actions
Download File
Edit File
Delete File
View Transforms
Subscribe
Mute Notifications
Award Token
Subscribers
None
File Metadata
Details
File Info
Storage
Attached
Created
Wed, Oct 16, 12:13
Size
5 KB
Mime Type
text/x-c
Expires
Fri, Oct 18, 12:13 (1 d, 21 h)
Engine
blob
Format
Raw Data
Handle
21703952
Attached To
rLAMMPS lammps
pair_coul_long_cs.cpp
View Options
/* ----------------------------------------------------------------------
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 author: Hendrik Heenen (hendrik.heenen@mytum.de)
------------------------------------------------------------------------- */
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "pair_coul_long_cs.h"
#include "atom.h"
#include "comm.h"
#include "force.h"
#include "kspace.h"
#include "neighbor.h"
#include "neigh_list.h"
#include "update.h"
#include "integrate.h"
#include "respa.h"
#include "memory.h"
#include "error.h"
using
namespace
LAMMPS_NS
;
#define EWALD_F 1.12837917
#define EWALD_P 9.95473818e-1
#define B0 -0.1335096380159268
#define B1 -2.57839507e-1
#define B2 -1.37203639e-1
#define B3 -8.88822059e-3
#define B4 -5.80844129e-3
#define B5 1.14652755e-1
#define EPSILON 1.0e-20
#define EPS_EWALD 1.0e-6
#define EPS_EWALD_SQR 1.0e-12
/* ---------------------------------------------------------------------- */
PairCoulLongCS
::
PairCoulLongCS
(
LAMMPS
*
lmp
)
:
PairCoulLong
(
lmp
)
{
ewaldflag
=
pppmflag
=
1
;
ftable
=
NULL
;
qdist
=
0.0
;
}
/* ---------------------------------------------------------------------- */
void
PairCoulLongCS
::
compute
(
int
eflag
,
int
vflag
)
{
int
i
,
j
,
ii
,
jj
,
inum
,
jnum
,
itable
,
itype
,
jtype
;
double
qtmp
,
xtmp
,
ytmp
,
ztmp
,
delx
,
dely
,
delz
,
ecoul
,
fpair
;
double
fraction
,
table
;
double
r
,
r2inv
,
forcecoul
,
factor_coul
;
double
grij
,
expm2
,
prefactor
,
t
,
erfc
,
u
;
int
*
ilist
,
*
jlist
,
*
numneigh
,
**
firstneigh
;
double
rsq
;
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
;
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_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
<
cut_coulsq
)
{
rsq
+=
EPSILON
;
// Add Epsilon for case: r = 0; Interaction must be removed by special bond;
r2inv
=
1.0
/
rsq
;
if
(
!
ncoultablebits
||
rsq
<=
tabinnersq
)
{
r
=
sqrt
(
rsq
);
prefactor
=
qqrd2e
*
scale
[
itype
][
jtype
]
*
qtmp
*
q
[
j
];
if
(
factor_coul
<
1.0
)
{
// When bonded parts are being calculated a minimal distance (EPS_EWALD)
// has to be added to the prefactor and erfc in order to make the
// used approximation functions for the Ewald correction valid
grij
=
g_ewald
*
(
r
+
EPS_EWALD
);
expm2
=
exp
(
-
grij
*
grij
);
t
=
1.0
/
(
1.0
+
EWALD_P
*
grij
);
u
=
1.0
-
t
;
erfc
=
t
*
(
1.
+
u
*
(
B0
+
u
*
(
B1
+
u
*
(
B2
+
u
*
(
B3
+
u
*
(
B4
+
u
*
B5
))))))
*
expm2
;
prefactor
/=
(
r
+
EPS_EWALD
);
forcecoul
=
prefactor
*
(
erfc
+
EWALD_F
*
grij
*
expm2
-
(
1.0
-
factor_coul
));
// Additionally r2inv needs to be accordingly modified since the later
// scaling of the overall force shall be consistent
r2inv
=
1.0
/
(
rsq
+
EPS_EWALD_SQR
);
}
else
{
grij
=
g_ewald
*
r
;
expm2
=
exp
(
-
grij
*
grij
);
t
=
1.0
/
(
1.0
+
EWALD_P
*
grij
);
u
=
1.0
-
t
;
erfc
=
t
*
(
1.
+
u
*
(
B0
+
u
*
(
B1
+
u
*
(
B2
+
u
*
(
B3
+
u
*
(
B4
+
u
*
B5
))))))
*
expm2
;
prefactor
/=
r
;
forcecoul
=
prefactor
*
(
erfc
+
EWALD_F
*
grij
*
expm2
);
}
}
else
{
union_int_float_t
rsq_lookup
;
rsq_lookup
.
f
=
rsq
;
itable
=
rsq_lookup
.
i
&
ncoulmask
;
itable
>>=
ncoulshiftbits
;
fraction
=
(
rsq_lookup
.
f
-
rtable
[
itable
])
*
drtable
[
itable
];
table
=
ftable
[
itable
]
+
fraction
*
dftable
[
itable
];
forcecoul
=
scale
[
itype
][
jtype
]
*
qtmp
*
q
[
j
]
*
table
;
if
(
factor_coul
<
1.0
)
{
table
=
ctable
[
itable
]
+
fraction
*
dctable
[
itable
];
prefactor
=
scale
[
itype
][
jtype
]
*
qtmp
*
q
[
j
]
*
table
;
forcecoul
-=
(
1.0
-
factor_coul
)
*
prefactor
;
}
}
fpair
=
forcecoul
*
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
;
}
if
(
eflag
)
{
if
(
!
ncoultablebits
||
rsq
<=
tabinnersq
)
ecoul
=
prefactor
*
erfc
;
else
{
table
=
etable
[
itable
]
+
fraction
*
detable
[
itable
];
ecoul
=
scale
[
itype
][
jtype
]
*
qtmp
*
q
[
j
]
*
table
;
}
if
(
factor_coul
<
1.0
)
ecoul
-=
(
1.0
-
factor_coul
)
*
prefactor
;
}
if
(
evflag
)
ev_tally
(
i
,
j
,
nlocal
,
newton_pair
,
0.0
,
ecoul
,
fpair
,
delx
,
dely
,
delz
);
}
}
}
if
(
vflag_fdotr
)
virial_fdotr_compute
();
}
Event Timeline
Log In to Comment