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rLAMMPS lammps
pair_gw.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 author: German Samolyuk (ORNL)
based on PairTersoff by Aidan Thompson (SNL)
------------------------------------------------------------------------- */
#include "math.h"
#include "stdio.h"
#include "stdlib.h"
#include "string.h"
#include "pair_gw.h"
#include "atom.h"
#include "neighbor.h"
#include "neigh_list.h"
#include "neigh_request.h"
#include "force.h"
#include "comm.h"
#include "memory.h"
#include "error.h"
#include "math_const.h"
using
namespace
LAMMPS_NS
;
using
namespace
MathConst
;
#define MAXLINE 1024
#define DELTA 4
/* ---------------------------------------------------------------------- */
PairGW
::
PairGW
(
LAMMPS
*
lmp
)
:
Pair
(
lmp
)
{
single_enable
=
0
;
restartinfo
=
0
;
one_coeff
=
1
;
manybody_flag
=
1
;
nelements
=
0
;
elements
=
NULL
;
nparams
=
maxparam
=
0
;
params
=
NULL
;
elem2param
=
NULL
;
map
=
NULL
;
}
/* ----------------------------------------------------------------------
check if allocated, since class can be destructed when incomplete
------------------------------------------------------------------------- */
PairGW
::~
PairGW
()
{
if
(
elements
)
for
(
int
i
=
0
;
i
<
nelements
;
i
++
)
delete
[]
elements
[
i
];
delete
[]
elements
;
memory
->
destroy
(
params
);
memory
->
destroy
(
elem2param
);
if
(
allocated
)
{
memory
->
destroy
(
setflag
);
memory
->
destroy
(
cutsq
);
delete
[]
map
;
}
}
/* ---------------------------------------------------------------------- */
void
PairGW
::
compute
(
int
eflag
,
int
vflag
)
{
int
i
,
j
,
k
,
ii
,
jj
,
kk
,
inum
,
jnum
;
int
itag
,
jtag
,
itype
,
jtype
,
ktype
,
iparam_ij
,
iparam_ijk
;
double
xtmp
,
ytmp
,
ztmp
,
delx
,
dely
,
delz
,
evdwl
,
fpair
;
double
rsq
,
rsq1
,
rsq2
;
double
delr1
[
3
],
delr2
[
3
],
fi
[
3
],
fj
[
3
],
fk
[
3
];
double
zeta_ij
,
prefactor
;
int
*
ilist
,
*
jlist
,
*
numneigh
,
**
firstneigh
;
evdwl
=
0.0
;
if
(
eflag
||
vflag
)
ev_setup
(
eflag
,
vflag
);
else
evflag
=
vflag_fdotr
=
vflag_atom
=
0
;
double
**
x
=
atom
->
x
;
double
**
f
=
atom
->
f
;
tagint
*
tag
=
atom
->
tag
;
int
*
type
=
atom
->
type
;
int
nlocal
=
atom
->
nlocal
;
int
newton_pair
=
force
->
newton_pair
;
inum
=
list
->
inum
;
ilist
=
list
->
ilist
;
numneigh
=
list
->
numneigh
;
firstneigh
=
list
->
firstneigh
;
// loop over full neighbor list of my atoms
for
(
ii
=
0
;
ii
<
inum
;
ii
++
)
{
i
=
ilist
[
ii
];
itag
=
tag
[
i
];
itype
=
map
[
type
[
i
]];
xtmp
=
x
[
i
][
0
];
ytmp
=
x
[
i
][
1
];
ztmp
=
x
[
i
][
2
];
// two-body interactions, skip half of them
jlist
=
firstneigh
[
i
];
jnum
=
numneigh
[
i
];
for
(
jj
=
0
;
jj
<
jnum
;
jj
++
)
{
j
=
jlist
[
jj
];
j
&=
NEIGHMASK
;
jtag
=
tag
[
j
];
if
(
itag
>
jtag
)
{
if
((
itag
+
jtag
)
%
2
==
0
)
continue
;
}
else
if
(
itag
<
jtag
)
{
if
((
itag
+
jtag
)
%
2
==
1
)
continue
;
}
else
{
if
(
x
[
j
][
2
]
<
x
[
i
][
2
])
continue
;
if
(
x
[
j
][
2
]
==
ztmp
&&
x
[
j
][
1
]
<
ytmp
)
continue
;
if
(
x
[
j
][
2
]
==
ztmp
&&
x
[
j
][
1
]
==
ytmp
&&
x
[
j
][
0
]
<
xtmp
)
continue
;
}
jtype
=
map
[
type
[
j
]];
delx
=
xtmp
-
x
[
j
][
0
];
dely
=
ytmp
-
x
[
j
][
1
];
delz
=
ztmp
-
x
[
j
][
2
];
rsq
=
delx
*
delx
+
dely
*
dely
+
delz
*
delz
;
iparam_ij
=
elem2param
[
itype
][
jtype
][
jtype
];
if
(
rsq
>
params
[
iparam_ij
].
cutsq
)
continue
;
repulsive
(
&
params
[
iparam_ij
],
rsq
,
fpair
,
eflag
,
evdwl
);
f
[
i
][
0
]
+=
delx
*
fpair
;
f
[
i
][
1
]
+=
dely
*
fpair
;
f
[
i
][
2
]
+=
delz
*
fpair
;
f
[
j
][
0
]
-=
delx
*
fpair
;
f
[
j
][
1
]
-=
dely
*
fpair
;
f
[
j
][
2
]
-=
delz
*
fpair
;
if
(
evflag
)
ev_tally
(
i
,
j
,
nlocal
,
newton_pair
,
evdwl
,
0.0
,
fpair
,
delx
,
dely
,
delz
);
}
// three-body interactions
// skip immediately if I-J is not within cutoff
for
(
jj
=
0
;
jj
<
jnum
;
jj
++
)
{
j
=
jlist
[
jj
];
j
&=
NEIGHMASK
;
jtype
=
map
[
type
[
j
]];
iparam_ij
=
elem2param
[
itype
][
jtype
][
jtype
];
delr1
[
0
]
=
x
[
j
][
0
]
-
xtmp
;
delr1
[
1
]
=
x
[
j
][
1
]
-
ytmp
;
delr1
[
2
]
=
x
[
j
][
2
]
-
ztmp
;
rsq1
=
delr1
[
0
]
*
delr1
[
0
]
+
delr1
[
1
]
*
delr1
[
1
]
+
delr1
[
2
]
*
delr1
[
2
];
if
(
rsq1
>
params
[
iparam_ij
].
cutsq
)
continue
;
// accumulate bondorder zeta for each i-j interaction via loop over k
zeta_ij
=
1.0
;
for
(
kk
=
0
;
kk
<
jnum
;
kk
++
)
{
if
(
jj
==
kk
)
continue
;
k
=
jlist
[
kk
];
k
&=
NEIGHMASK
;
ktype
=
map
[
type
[
k
]];
iparam_ijk
=
elem2param
[
itype
][
jtype
][
ktype
];
delr2
[
0
]
=
x
[
k
][
0
]
-
xtmp
;
delr2
[
1
]
=
x
[
k
][
1
]
-
ytmp
;
delr2
[
2
]
=
x
[
k
][
2
]
-
ztmp
;
rsq2
=
delr2
[
0
]
*
delr2
[
0
]
+
delr2
[
1
]
*
delr2
[
1
]
+
delr2
[
2
]
*
delr2
[
2
];
if
(
rsq2
>
params
[
iparam_ijk
].
cutsq
)
continue
;
zeta_ij
+=
zeta
(
&
params
[
iparam_ijk
],
rsq1
,
rsq2
,
delr1
,
delr2
);
}
// pairwise force due to zeta
force_zeta
(
&
params
[
iparam_ij
],
rsq1
,
zeta_ij
,
fpair
,
prefactor
,
eflag
,
evdwl
);
f
[
i
][
0
]
+=
delr1
[
0
]
*
fpair
;
f
[
i
][
1
]
+=
delr1
[
1
]
*
fpair
;
f
[
i
][
2
]
+=
delr1
[
2
]
*
fpair
;
f
[
j
][
0
]
-=
delr1
[
0
]
*
fpair
;
f
[
j
][
1
]
-=
delr1
[
1
]
*
fpair
;
f
[
j
][
2
]
-=
delr1
[
2
]
*
fpair
;
if
(
evflag
)
ev_tally
(
i
,
j
,
nlocal
,
newton_pair
,
evdwl
,
0.0
,
-
fpair
,
-
delr1
[
0
],
-
delr1
[
1
],
-
delr1
[
2
]);
// attractive term via loop over k
for
(
kk
=
0
;
kk
<
jnum
;
kk
++
)
{
if
(
jj
==
kk
)
continue
;
k
=
jlist
[
kk
];
k
&=
NEIGHMASK
;
ktype
=
map
[
type
[
k
]];
iparam_ijk
=
elem2param
[
itype
][
jtype
][
ktype
];
delr2
[
0
]
=
x
[
k
][
0
]
-
xtmp
;
delr2
[
1
]
=
x
[
k
][
1
]
-
ytmp
;
delr2
[
2
]
=
x
[
k
][
2
]
-
ztmp
;
rsq2
=
delr2
[
0
]
*
delr2
[
0
]
+
delr2
[
1
]
*
delr2
[
1
]
+
delr2
[
2
]
*
delr2
[
2
];
if
(
rsq2
>
params
[
iparam_ijk
].
cutsq
)
continue
;
attractive
(
&
params
[
iparam_ijk
],
prefactor
,
rsq1
,
rsq2
,
delr1
,
delr2
,
fi
,
fj
,
fk
);
f
[
i
][
0
]
+=
fi
[
0
];
f
[
i
][
1
]
+=
fi
[
1
];
f
[
i
][
2
]
+=
fi
[
2
];
f
[
j
][
0
]
+=
fj
[
0
];
f
[
j
][
1
]
+=
fj
[
1
];
f
[
j
][
2
]
+=
fj
[
2
];
f
[
k
][
0
]
+=
fk
[
0
];
f
[
k
][
1
]
+=
fk
[
1
];
f
[
k
][
2
]
+=
fk
[
2
];
if
(
vflag_atom
)
v_tally3
(
i
,
j
,
k
,
fj
,
fk
,
delr1
,
delr2
);
}
// kk
}
// jj
}
// ii
if
(
vflag_fdotr
)
virial_fdotr_compute
();
}
/* ---------------------------------------------------------------------- */
void
PairGW
::
allocate
()
{
allocated
=
1
;
int
n
=
atom
->
ntypes
;
memory
->
create
(
setflag
,
n
+
1
,
n
+
1
,
"pair:setflag"
);
memory
->
create
(
cutsq
,
n
+
1
,
n
+
1
,
"pair:cutsq"
);
map
=
new
int
[
n
+
1
];
}
/* ----------------------------------------------------------------------
global settings
------------------------------------------------------------------------- */
void
PairGW
::
settings
(
int
narg
,
char
**
arg
)
{
if
(
narg
!=
0
)
error
->
all
(
FLERR
,
"Illegal pair_style command"
);
}
/* ----------------------------------------------------------------------
set coeffs for one or more type pairs
------------------------------------------------------------------------- */
void
PairGW
::
coeff
(
int
narg
,
char
**
arg
)
{
int
i
,
j
,
n
;
if
(
!
allocated
)
allocate
();
if
(
narg
!=
3
+
atom
->
ntypes
)
error
->
all
(
FLERR
,
"Incorrect args for pair coefficients"
);
// insure I,J args are * *
if
(
strcmp
(
arg
[
0
],
"*"
)
!=
0
||
strcmp
(
arg
[
1
],
"*"
)
!=
0
)
error
->
all
(
FLERR
,
"Incorrect args for pair coefficients"
);
// read args that map atom types to elements in potential file
// map[i] = which element the Ith atom type is, -1 if NULL
// nelements = # of unique elements
// elements = list of element names
if
(
elements
)
{
for
(
i
=
0
;
i
<
nelements
;
i
++
)
delete
[]
elements
[
i
];
delete
[]
elements
;
}
elements
=
new
char
*
[
atom
->
ntypes
];
for
(
i
=
0
;
i
<
atom
->
ntypes
;
i
++
)
elements
[
i
]
=
NULL
;
nelements
=
0
;
for
(
i
=
3
;
i
<
narg
;
i
++
)
{
if
(
strcmp
(
arg
[
i
],
"NULL"
)
==
0
)
{
map
[
i
-
2
]
=
-
1
;
continue
;
}
for
(
j
=
0
;
j
<
nelements
;
j
++
)
if
(
strcmp
(
arg
[
i
],
elements
[
j
])
==
0
)
break
;
map
[
i
-
2
]
=
j
;
if
(
j
==
nelements
)
{
n
=
strlen
(
arg
[
i
])
+
1
;
elements
[
j
]
=
new
char
[
n
];
strcpy
(
elements
[
j
],
arg
[
i
]);
nelements
++
;
}
}
// read potential file and initialize potential parameters
read_file
(
arg
[
2
]);
setup_params
();
// clear setflag since coeff() called once with I,J = * *
n
=
atom
->
ntypes
;
for
(
i
=
1
;
i
<=
n
;
i
++
)
for
(
j
=
i
;
j
<=
n
;
j
++
)
setflag
[
i
][
j
]
=
0
;
// set setflag i,j for type pairs where both are mapped to elements
int
count
=
0
;
for
(
i
=
1
;
i
<=
n
;
i
++
)
for
(
j
=
i
;
j
<=
n
;
j
++
)
if
(
map
[
i
]
>=
0
&&
map
[
j
]
>=
0
)
{
setflag
[
i
][
j
]
=
1
;
count
++
;
}
if
(
count
==
0
)
error
->
all
(
FLERR
,
"Incorrect args for pair coefficients"
);
}
/* ----------------------------------------------------------------------
init specific to this pair style
------------------------------------------------------------------------- */
void
PairGW
::
init_style
()
{
if
(
atom
->
tag_enable
==
0
)
error
->
all
(
FLERR
,
"Pair style GW requires atom IDs"
);
if
(
force
->
newton_pair
==
0
)
error
->
all
(
FLERR
,
"Pair style GW requires newton pair on"
);
// need a full neighbor list
int
irequest
=
neighbor
->
request
(
this
,
instance_me
);
neighbor
->
requests
[
irequest
]
->
half
=
0
;
neighbor
->
requests
[
irequest
]
->
full
=
1
;
}
/* ----------------------------------------------------------------------
init for one type pair i,j and corresponding j,i
------------------------------------------------------------------------- */
double
PairGW
::
init_one
(
int
i
,
int
j
)
{
if
(
setflag
[
i
][
j
]
==
0
)
error
->
all
(
FLERR
,
"All pair coeffs are not set"
);
return
cutmax
;
}
/* ---------------------------------------------------------------------- */
void
PairGW
::
read_file
(
char
*
file
)
{
int
params_per_line
=
17
;
char
**
words
=
new
char
*
[
params_per_line
+
1
];
memory
->
sfree
(
params
);
params
=
NULL
;
nparams
=
maxparam
=
0
;
// open file on proc 0
FILE
*
fp
;
if
(
comm
->
me
==
0
)
{
fp
=
force
->
open_potential
(
file
);
if
(
fp
==
NULL
)
{
char
str
[
128
];
sprintf
(
str
,
"Cannot open GW potential file %s"
,
file
);
error
->
one
(
FLERR
,
str
);
}
}
// read each line out of file, skipping blank lines or leading '#'
// store line of params if all 3 element tags are in element list
int
n
,
nwords
,
ielement
,
jelement
,
kelement
;
char
line
[
MAXLINE
],
*
ptr
;
int
eof
=
0
;
while
(
1
)
{
if
(
comm
->
me
==
0
)
{
ptr
=
fgets
(
line
,
MAXLINE
,
fp
);
if
(
ptr
==
NULL
)
{
eof
=
1
;
fclose
(
fp
);
}
else
n
=
strlen
(
line
)
+
1
;
}
MPI_Bcast
(
&
eof
,
1
,
MPI_INT
,
0
,
world
);
if
(
eof
)
break
;
MPI_Bcast
(
&
n
,
1
,
MPI_INT
,
0
,
world
);
MPI_Bcast
(
line
,
n
,
MPI_CHAR
,
0
,
world
);
// strip comment, skip line if blank
if
((
ptr
=
strchr
(
line
,
'#'
)))
*
ptr
=
'\0'
;
nwords
=
atom
->
count_words
(
line
);
if
(
nwords
==
0
)
continue
;
// concatenate additional lines until have params_per_line words
while
(
nwords
<
params_per_line
)
{
n
=
strlen
(
line
);
if
(
comm
->
me
==
0
)
{
ptr
=
fgets
(
&
line
[
n
],
MAXLINE
-
n
,
fp
);
if
(
ptr
==
NULL
)
{
eof
=
1
;
fclose
(
fp
);
}
else
n
=
strlen
(
line
)
+
1
;
}
MPI_Bcast
(
&
eof
,
1
,
MPI_INT
,
0
,
world
);
if
(
eof
)
break
;
MPI_Bcast
(
&
n
,
1
,
MPI_INT
,
0
,
world
);
MPI_Bcast
(
line
,
n
,
MPI_CHAR
,
0
,
world
);
if
((
ptr
=
strchr
(
line
,
'#'
)))
*
ptr
=
'\0'
;
nwords
=
atom
->
count_words
(
line
);
}
if
(
nwords
!=
params_per_line
)
error
->
all
(
FLERR
,
"Incorrect format in GW potential file"
);
// words = ptrs to all words in line
nwords
=
0
;
words
[
nwords
++
]
=
strtok
(
line
,
"
\t\n\r\f
"
);
while
((
words
[
nwords
++
]
=
strtok
(
NULL
,
"
\t\n\r\f
"
)))
continue
;
// ielement,jelement,kelement = 1st args
// if all 3 args are in element list, then parse this line
// else skip to next line
for
(
ielement
=
0
;
ielement
<
nelements
;
ielement
++
)
if
(
strcmp
(
words
[
0
],
elements
[
ielement
])
==
0
)
break
;
if
(
ielement
==
nelements
)
continue
;
for
(
jelement
=
0
;
jelement
<
nelements
;
jelement
++
)
if
(
strcmp
(
words
[
1
],
elements
[
jelement
])
==
0
)
break
;
if
(
jelement
==
nelements
)
continue
;
for
(
kelement
=
0
;
kelement
<
nelements
;
kelement
++
)
if
(
strcmp
(
words
[
2
],
elements
[
kelement
])
==
0
)
break
;
if
(
kelement
==
nelements
)
continue
;
// load up parameter settings and error check their values
if
(
nparams
==
maxparam
)
{
maxparam
+=
DELTA
;
params
=
(
Param
*
)
memory
->
srealloc
(
params
,
maxparam
*
sizeof
(
Param
),
"pair:params"
);
}
params
[
nparams
].
ielement
=
ielement
;
params
[
nparams
].
jelement
=
jelement
;
params
[
nparams
].
kelement
=
kelement
;
params
[
nparams
].
powerm
=
atof
(
words
[
3
]);
params
[
nparams
].
gamma
=
atof
(
words
[
4
]);
params
[
nparams
].
lam3
=
atof
(
words
[
5
]);
params
[
nparams
].
c
=
atof
(
words
[
6
]);
params
[
nparams
].
d
=
atof
(
words
[
7
]);
params
[
nparams
].
h
=
atof
(
words
[
8
]);
params
[
nparams
].
powern
=
atof
(
words
[
9
]);
params
[
nparams
].
beta
=
atof
(
words
[
10
]);
params
[
nparams
].
lam2
=
atof
(
words
[
11
]);
params
[
nparams
].
bigb
=
atof
(
words
[
12
]);
params
[
nparams
].
bigr
=
atof
(
words
[
13
]);
params
[
nparams
].
bigd
=
atof
(
words
[
14
]);
params
[
nparams
].
lam1
=
atof
(
words
[
15
]);
params
[
nparams
].
biga
=
atof
(
words
[
16
]);
// currently only allow m exponent of 1 or 3
params
[
nparams
].
powermint
=
int
(
params
[
nparams
].
powerm
);
if
(
params
[
nparams
].
c
<
0.0
||
params
[
nparams
].
d
<
0.0
||
params
[
nparams
].
powern
<
0.0
||
params
[
nparams
].
beta
<
0.0
||
params
[
nparams
].
lam2
<
0.0
||
params
[
nparams
].
bigb
<
0.0
||
params
[
nparams
].
bigr
<
0.0
||
params
[
nparams
].
bigd
<
0.0
||
params
[
nparams
].
bigd
>
params
[
nparams
].
bigr
||
params
[
nparams
].
lam1
<
0.0
||
params
[
nparams
].
biga
<
0.0
||
params
[
nparams
].
powerm
-
params
[
nparams
].
powermint
!=
0.0
||
(
params
[
nparams
].
powermint
!=
3
&&
params
[
nparams
].
powermint
!=
1
)
||
params
[
nparams
].
gamma
<
0.0
)
error
->
all
(
FLERR
,
"Illegal GW parameter"
);
nparams
++
;
}
delete
[]
words
;
}
/* ---------------------------------------------------------------------- */
void
PairGW
::
setup_params
()
{
int
i
,
j
,
k
,
m
,
n
;
// set elem2param for all element triplet combinations
// must be a single exact match to lines read from file
// do not allow for ACB in place of ABC
memory
->
destroy
(
elem2param
);
memory
->
create
(
elem2param
,
nelements
,
nelements
,
nelements
,
"pair:elem2param"
);
for
(
i
=
0
;
i
<
nelements
;
i
++
)
for
(
j
=
0
;
j
<
nelements
;
j
++
)
for
(
k
=
0
;
k
<
nelements
;
k
++
)
{
n
=
-
1
;
for
(
m
=
0
;
m
<
nparams
;
m
++
)
{
if
(
i
==
params
[
m
].
ielement
&&
j
==
params
[
m
].
jelement
&&
k
==
params
[
m
].
kelement
)
{
if
(
n
>=
0
)
error
->
all
(
FLERR
,
"Potential file has duplicate entry"
);
n
=
m
;
}
}
if
(
n
<
0
)
error
->
all
(
FLERR
,
"Potential file is missing an entry"
);
elem2param
[
i
][
j
][
k
]
=
n
;
}
// compute parameter values derived from inputs
for
(
m
=
0
;
m
<
nparams
;
m
++
)
{
params
[
m
].
cut
=
params
[
m
].
bigr
+
params
[
m
].
bigd
;
params
[
m
].
cutsq
=
params
[
m
].
cut
*
params
[
m
].
cut
;
params
[
m
].
c1
=
pow
(
2.0
*
params
[
m
].
powern
*
1.0e-16
,
-
1.0
/
params
[
m
].
powern
);
params
[
m
].
c2
=
pow
(
2.0
*
params
[
m
].
powern
*
1.0e-8
,
-
1.0
/
params
[
m
].
powern
);
params
[
m
].
c3
=
1.0
/
params
[
m
].
c2
;
params
[
m
].
c4
=
1.0
/
params
[
m
].
c1
;
}
// set cutmax to max of all params
cutmax
=
0.0
;
for
(
m
=
0
;
m
<
nparams
;
m
++
)
if
(
params
[
m
].
cut
>
cutmax
)
cutmax
=
params
[
m
].
cut
;
}
/* ---------------------------------------------------------------------- */
void
PairGW
::
repulsive
(
Param
*
param
,
double
rsq
,
double
&
fforce
,
int
eflag
,
double
&
eng
)
{
double
r
,
tmp_fc
,
tmp_fc_d
,
tmp_exp
;
r
=
sqrt
(
rsq
);
tmp_fc
=
gw_fc
(
r
,
param
);
tmp_fc_d
=
gw_fc_d
(
r
,
param
);
tmp_exp
=
exp
(
-
param
->
lam1
*
r
);
fforce
=
-
param
->
biga
*
tmp_exp
*
(
tmp_fc_d
-
tmp_fc
*
param
->
lam1
)
/
r
;
if
(
eflag
)
eng
=
tmp_fc
*
param
->
biga
*
tmp_exp
;
}
/* ---------------------------------------------------------------------- */
double
PairGW
::
zeta
(
Param
*
param
,
double
rsqij
,
double
rsqik
,
double
*
delrij
,
double
*
delrik
)
{
double
rij
,
rik
,
costheta
,
arg
,
ex_delr
;
rij
=
sqrt
(
rsqij
);
rik
=
sqrt
(
rsqik
);
costheta
=
(
delrij
[
0
]
*
delrik
[
0
]
+
delrij
[
1
]
*
delrik
[
1
]
+
delrij
[
2
]
*
delrik
[
2
])
/
(
rij
*
rik
);
if
(
param
->
powermint
==
3
)
arg
=
pow
(
param
->
lam3
*
(
rij
-
rik
),
3.0
);
else
arg
=
param
->
lam3
*
(
rij
-
rik
);
if
(
arg
>
69.0776
)
ex_delr
=
1.e30
;
else
if
(
arg
<
-
69.0776
)
ex_delr
=
0.0
;
else
ex_delr
=
exp
(
arg
);
return
gw_fc
(
rik
,
param
)
*
gw_gijk
(
costheta
,
param
)
*
ex_delr
;
}
/* ---------------------------------------------------------------------- */
void
PairGW
::
force_zeta
(
Param
*
param_i
,
double
rsq
,
double
zeta_ij
,
double
&
fforce
,
double
&
prefactor
,
int
eflag
,
double
&
eng
)
{
double
r
,
fa
,
fa_d
,
bij
;
r
=
sqrt
(
rsq
);
fa
=
gw_fa
(
r
,
param_i
);
fa_d
=
gw_fa_d
(
r
,
param_i
);
bij
=
gw_bij
(
zeta_ij
,
param_i
);
fforce
=
0.5
*
bij
*
fa_d
/
r
;
prefactor
=
-
0.5
*
fa
*
gw_bij_d
(
zeta_ij
,
param_i
);
if
(
eflag
)
eng
=
0.5
*
bij
*
fa
;
}
/* ----------------------------------------------------------------------
attractive term
use param_ij cutoff for rij test
use param_ijk cutoff for rik test
------------------------------------------------------------------------- */
void
PairGW
::
attractive
(
Param
*
param
,
double
prefactor
,
double
rsqij
,
double
rsqik
,
double
*
delrij
,
double
*
delrik
,
double
*
fi
,
double
*
fj
,
double
*
fk
)
{
double
rij_hat
[
3
],
rik_hat
[
3
];
double
rij
,
rijinv
,
rik
,
rikinv
;
rij
=
sqrt
(
rsqij
);
rijinv
=
1.0
/
rij
;
vec3_scale
(
rijinv
,
delrij
,
rij_hat
);
rik
=
sqrt
(
rsqik
);
rikinv
=
1.0
/
rik
;
vec3_scale
(
rikinv
,
delrik
,
rik_hat
);
gw_zetaterm_d
(
prefactor
,
rij_hat
,
rij
,
rik_hat
,
rik
,
fi
,
fj
,
fk
,
param
);
}
/* ---------------------------------------------------------------------- */
double
PairGW
::
gw_fc
(
double
r
,
Param
*
param
)
{
double
gw_R
=
param
->
bigr
;
double
gw_D
=
param
->
bigd
;
if
(
r
<
gw_R
-
gw_D
)
return
1.0
;
if
(
r
>
gw_R
+
gw_D
)
return
0.0
;
return
0.5
*
(
1.0
-
sin
(
MY_PI2
*
(
r
-
gw_R
)
/
gw_D
));
}
/* ---------------------------------------------------------------------- */
double
PairGW
::
gw_fc_d
(
double
r
,
Param
*
param
)
{
double
gw_R
=
param
->
bigr
;
double
gw_D
=
param
->
bigd
;
if
(
r
<
gw_R
-
gw_D
)
return
0.0
;
if
(
r
>
gw_R
+
gw_D
)
return
0.0
;
return
-
(
MY_PI4
/
gw_D
)
*
cos
(
MY_PI2
*
(
r
-
gw_R
)
/
gw_D
);
}
/* ---------------------------------------------------------------------- */
double
PairGW
::
gw_fa
(
double
r
,
Param
*
param
)
{
if
(
r
>
param
->
bigr
+
param
->
bigd
)
return
0.0
;
return
-
param
->
bigb
*
exp
(
-
param
->
lam2
*
r
)
*
gw_fc
(
r
,
param
);
}
/* ---------------------------------------------------------------------- */
double
PairGW
::
gw_fa_d
(
double
r
,
Param
*
param
)
{
if
(
r
>
param
->
bigr
+
param
->
bigd
)
return
0.0
;
return
param
->
bigb
*
exp
(
-
param
->
lam2
*
r
)
*
(
param
->
lam2
*
gw_fc
(
r
,
param
)
-
gw_fc_d
(
r
,
param
));
}
/* ---------------------------------------------------------------------- */
double
PairGW
::
gw_bij
(
double
zeta_ij
,
Param
*
param_i
)
{
double
tmp
=
param_i
->
beta
*
zeta_ij
;
return
pow
(
tmp
,
-
param_i
->
powern
);
}
/* ---------------------------------------------------------------------- */
double
PairGW
::
gw_bij_d
(
double
zeta_ij
,
Param
*
param_i
)
{
double
tmp
=
param_i
->
beta
*
zeta_ij
;
return
-
param_i
->
powern
*
pow
(
tmp
,
-
param_i
->
powern
-
1
)
*
tmp
/
zeta_ij
;
}
/* ---------------------------------------------------------------------- */
void
PairGW
::
gw_zetaterm_d
(
double
prefactor
,
double
*
rij_hat
,
double
rij
,
double
*
rik_hat
,
double
rik
,
double
*
dri
,
double
*
drj
,
double
*
drk
,
Param
*
param
)
{
double
gijk
,
gijk_d
,
ex_delr
,
ex_delr_d
,
fc
,
dfc
,
cos_theta
,
tmp
;
double
dcosdri
[
3
],
dcosdrj
[
3
],
dcosdrk
[
3
];
fc
=
gw_fc
(
rik
,
param
);
dfc
=
gw_fc_d
(
rik
,
param
);
if
(
param
->
powermint
==
3
)
tmp
=
pow
(
param
->
lam3
*
(
rij
-
rik
),
3.0
);
else
tmp
=
param
->
lam3
*
(
rij
-
rik
);
if
(
tmp
>
69.0776
)
ex_delr
=
1.e30
;
else
if
(
tmp
<
-
69.0776
)
ex_delr
=
0.0
;
else
ex_delr
=
exp
(
tmp
);
if
(
param
->
powermint
==
3
)
ex_delr_d
=
3.0
*
pow
(
param
->
lam3
,
3.0
)
*
pow
(
rij
-
rik
,
2.0
)
*
ex_delr
;
else
ex_delr_d
=
param
->
lam3
*
ex_delr
;
cos_theta
=
vec3_dot
(
rij_hat
,
rik_hat
);
gijk
=
gw_gijk
(
cos_theta
,
param
);
gijk_d
=
gw_gijk_d
(
cos_theta
,
param
);
costheta_d
(
rij_hat
,
rij
,
rik_hat
,
rik
,
dcosdri
,
dcosdrj
,
dcosdrk
);
// compute the derivative wrt Ri
// dri = -dfc*gijk*ex_delr*rik_hat;
// dri += fc*gijk_d*ex_delr*dcosdri;
// dri += fc*gijk*ex_delr_d*(rik_hat - rij_hat);
vec3_scale
(
-
dfc
*
gijk
*
ex_delr
,
rik_hat
,
dri
);
vec3_scaleadd
(
fc
*
gijk_d
*
ex_delr
,
dcosdri
,
dri
,
dri
);
vec3_scaleadd
(
fc
*
gijk
*
ex_delr_d
,
rik_hat
,
dri
,
dri
);
vec3_scaleadd
(
-
fc
*
gijk
*
ex_delr_d
,
rij_hat
,
dri
,
dri
);
vec3_scale
(
prefactor
,
dri
,
dri
);
// compute the derivative wrt Rj
// drj = fc*gijk_d*ex_delr*dcosdrj;
// drj += fc*gijk*ex_delr_d*rij_hat;
vec3_scale
(
fc
*
gijk_d
*
ex_delr
,
dcosdrj
,
drj
);
vec3_scaleadd
(
fc
*
gijk
*
ex_delr_d
,
rij_hat
,
drj
,
drj
);
vec3_scale
(
prefactor
,
drj
,
drj
);
// compute the derivative wrt Rk
// drk = dfc*gijk*ex_delr*rik_hat;
// drk += fc*gijk_d*ex_delr*dcosdrk;
// drk += -fc*gijk*ex_delr_d*rik_hat;
vec3_scale
(
dfc
*
gijk
*
ex_delr
,
rik_hat
,
drk
);
vec3_scaleadd
(
fc
*
gijk_d
*
ex_delr
,
dcosdrk
,
drk
,
drk
);
vec3_scaleadd
(
-
fc
*
gijk
*
ex_delr_d
,
rik_hat
,
drk
,
drk
);
vec3_scale
(
prefactor
,
drk
,
drk
);
}
/* ---------------------------------------------------------------------- */
void
PairGW
::
costheta_d
(
double
*
rij_hat
,
double
rij
,
double
*
rik_hat
,
double
rik
,
double
*
dri
,
double
*
drj
,
double
*
drk
)
{
// first element is devative wrt Ri, second wrt Rj, third wrt Rk
double
cos_theta
=
vec3_dot
(
rij_hat
,
rik_hat
);
vec3_scaleadd
(
-
cos_theta
,
rij_hat
,
rik_hat
,
drj
);
vec3_scale
(
1.0
/
rij
,
drj
,
drj
);
vec3_scaleadd
(
-
cos_theta
,
rik_hat
,
rij_hat
,
drk
);
vec3_scale
(
1.0
/
rik
,
drk
,
drk
);
vec3_add
(
drj
,
drk
,
dri
);
vec3_scale
(
-
1.0
,
dri
,
dri
);
}
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