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Created
Sun, Aug 25, 04:07
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3 KB
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text/x-c
Expires
Tue, Aug 27, 04:07 (1 d, 23 h)
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20052285
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rLAMMPS lammps
simple.c
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/* ----------------------------------------------------------------------
LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
www.cs.sandia.gov/~sjplimp/lammps.html
Steve Plimpton, sjplimp@sandia.gov, Sandia National Laboratories
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.
------------------------------------------------------------------------- */
/* c_driver = simple example of how an umbrella program
can invoke LAMMPS as a library on some subset of procs
Syntax: simpleC P in.lammps
P = # of procs to run LAMMPS on
must be <= # of procs the driver code itself runs on
in.lammps = LAMMPS input script
See README for compilation instructions */
#include "stdio.h"
#include "stdlib.h"
#include "string.h"
#include "mpi.h"
#include "library.h"
/* this is a LAMMPS include file */
int
main
(
int
narg
,
char
**
arg
)
{
/* setup MPI and various communicators
driver runs on all procs in MPI_COMM_WORLD
comm_lammps only has 1st P procs (could be all or any subset) */
MPI_Init
(
&
narg
,
&
arg
);
if
(
narg
!=
3
)
{
printf
(
"Syntax: simpleC P in.lammps
\n
"
);
exit
(
1
);
}
int
me
,
nprocs
;
MPI_Comm_rank
(
MPI_COMM_WORLD
,
&
me
);
MPI_Comm_size
(
MPI_COMM_WORLD
,
&
nprocs
);
int
nprocs_lammps
=
atoi
(
arg
[
1
]);
if
(
nprocs_lammps
>
nprocs
)
{
if
(
me
==
0
)
printf
(
"ERROR: LAMMPS cannot use more procs than available
\n
"
);
MPI_Abort
(
MPI_COMM_WORLD
,
1
);
}
int
lammps
;
if
(
me
<
nprocs_lammps
)
lammps
=
1
;
else
lammps
=
MPI_UNDEFINED
;
MPI_Comm
comm_lammps
;
MPI_Comm_split
(
MPI_COMM_WORLD
,
lammps
,
0
,
&
comm_lammps
);
/* open LAMMPS input script */
FILE
*
fp
;
if
(
me
==
0
)
{
fp
=
fopen
(
arg
[
2
],
"r"
);
if
(
fp
==
NULL
)
{
printf
(
"ERROR: Could not open LAMMPS input script
\n
"
);
MPI_Abort
(
MPI_COMM_WORLD
,
1
);
}
}
/* run the input script thru LAMMPS one line at a time until end-of-file
driver proc 0 reads a line, Bcasts it to all procs
(could just send it to proc 0 of comm_lammps and let it Bcast)
all LAMMPS procs call lammps_command() on the line */
void
*
ptr
;
if
(
lammps
==
1
)
lammps_open
(
0
,
NULL
,
comm_lammps
,
&
ptr
);
int
n
;
char
line
[
1024
];
while
(
1
)
{
if
(
me
==
0
)
{
if
(
fgets
(
line
,
1024
,
fp
)
==
NULL
)
n
=
0
;
else
n
=
strlen
(
line
)
+
1
;
if
(
n
==
0
)
fclose
(
fp
);
}
MPI_Bcast
(
&
n
,
1
,
MPI_INT
,
0
,
MPI_COMM_WORLD
);
if
(
n
==
0
)
break
;
MPI_Bcast
(
line
,
n
,
MPI_CHAR
,
0
,
MPI_COMM_WORLD
);
if
(
lammps
==
1
)
lammps_command
(
ptr
,
line
);
}
/* run 10 more steps
get coords from LAMMPS
change coords of 1st atom
put coords back into LAMMPS
run a single step with changed coords */
if
(
lammps
==
1
)
{
lammps_command
(
ptr
,
"run 10"
);
int
natoms
=
lammps_get_natoms
(
ptr
);
double
*
x
=
(
double
*
)
malloc
(
3
*
natoms
*
sizeof
(
double
));
lammps_gather_atoms
(
ptr
,
"x"
,
1
,
3
,
x
);
double
epsilon
=
0.1
;
x
[
0
]
+=
epsilon
;
lammps_scatter_atoms
(
ptr
,
"x"
,
1
,
3
,
x
);
free
(
x
);
lammps_command
(
ptr
,
"run 1"
);
}
if
(
lammps
==
1
)
lammps_close
(
ptr
);
/* close down MPI */
MPI_Finalize
();
}
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