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min_cg_fr.cpp
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Wed, Sep 18, 18:34
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Fri, Sep 20, 18:34 (1 d, 23 h)
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rLAMMPS lammps
min_cg_fr.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 "mpi.h"
#include "min_cg_fr.h"
#include "atom.h"
#include "update.h"
#include "output.h"
#include "timer.h"
using
namespace
LAMMPS_NS
;
#define MIN(A,B) ((A) < (B)) ? (A) : (B)
#define MAX(A,B) ((A) > (B)) ? (A) : (B)
#define EPS 1.0e-6
/* ---------------------------------------------------------------------- */
MinCGFR
::
MinCGFR
(
LAMMPS
*
lmp
)
:
MinCG
(
lmp
)
{}
/* ----------------------------------------------------------------------
minimization via conjugate gradient iterations
Fletcher-Reeves formulation
------------------------------------------------------------------------- */
void
MinCGFR
::
iterate
(
int
n
)
{
int
i
,
gradsearch
,
fail
;
double
alpha
,
beta
,
gg
,
dot
,
dotall
;
double
*
f
;
f
=
atom
->
f
[
0
];
for
(
int
i
=
0
;
i
<
ndof
;
i
++
)
h
[
i
]
=
g
[
i
]
=
f
[
i
];
dot
=
0.0
;
for
(
i
=
0
;
i
<
ndof
;
i
++
)
dot
+=
f
[
i
]
*
f
[
i
];
MPI_Allreduce
(
&
dot
,
&
gg
,
1
,
MPI_DOUBLE
,
MPI_SUM
,
world
);
neval
=
0
;
gradsearch
=
1
;
for
(
niter
=
0
;
niter
<
n
;
niter
++
)
{
update
->
ntimestep
++
;
// line minimization along direction h from current atom->x
eprevious
=
ecurrent
;
fail
=
(
this
->*
linemin
)(
ndof
,
atom
->
x
[
0
],
h
,
ecurrent
,
dmin
,
dmax
,
alpha
,
neval
);
// if max_eval exceeded, all done
// if linemin failed or energy did not decrease sufficiently:
// all done if searched in grad direction
// else force next search to be in grad direction (CG restart)
if
(
neval
>=
update
->
max_eval
)
break
;
if
(
fail
||
fabs
(
ecurrent
-
eprevious
)
<=
update
->
tolerance
*
0.5
*
(
fabs
(
ecurrent
)
+
fabs
(
eprevious
)
+
EPS
))
{
if
(
gradsearch
==
1
)
break
;
gradsearch
=
-
1
;
}
// update h from new f = -Grad(x) and old g
// old g,h must have migrated with atoms to do this correctly
// done if size sq of grad vector < EPS
// force new search dir to be grad dir if need to restart CG
// set gradsesarch to 1 if will search in grad dir on next iteration
f
=
atom
->
f
[
0
];
dot
=
0.0
;
for
(
i
=
0
;
i
<
ndof
;
i
++
)
dot
+=
f
[
i
]
*
f
[
i
];
MPI_Allreduce
(
&
dot
,
&
dotall
,
1
,
MPI_DOUBLE
,
MPI_SUM
,
world
);
beta
=
dotall
/
gg
;
gg
=
dotall
;
if
(
gg
<
EPS
)
break
;
if
(
gradsearch
==
-
1
)
beta
=
0.0
;
if
(
beta
==
0.0
)
gradsearch
=
1
;
else
gradsearch
=
0
;
for
(
i
=
0
;
i
<
ndof
;
i
++
)
{
g
[
i
]
=
f
[
i
];
h
[
i
]
=
g
[
i
]
+
beta
*
h
[
i
];
}
// output for thermo, dump, restart files
if
(
output
->
next
==
update
->
ntimestep
)
{
timer
->
stamp
();
output
->
write
(
update
->
ntimestep
);
timer
->
stamp
(
TIME_OUTPUT
);
}
}
}
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