2011-06-09 04:56:17 +08:00
|
|
|
"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c
|
|
|
|
|
|
|
|
:link(lws,http://lammps.sandia.gov)
|
|
|
|
:link(ld,Manual.html)
|
|
|
|
:link(lc,Section_commands.html#comm)
|
|
|
|
|
|
|
|
:line
|
|
|
|
|
|
|
|
pair_style adp command :h3
|
2011-10-07 01:32:51 +08:00
|
|
|
pair_style adp/omp command :h3
|
2011-06-09 04:56:17 +08:00
|
|
|
|
|
|
|
[Syntax:]
|
|
|
|
|
|
|
|
pair_style adp :pre
|
|
|
|
|
|
|
|
[Examples:]
|
|
|
|
|
|
|
|
pair_style adp
|
|
|
|
pair_coeff * * Ta.adp Ta
|
|
|
|
pair_coeff * * ../potentials/AlCu.adp Al Al Cu :pre
|
|
|
|
|
|
|
|
[Description:]
|
|
|
|
|
|
|
|
Style {adp} computes pairwise interactions for metals and metal alloys
|
|
|
|
using the angular dependent potential (ADP) of "(Mishin)"_#Mishin,
|
|
|
|
which is a generalization of the "embedded atom method (EAM)
|
2011-06-20 23:10:04 +08:00
|
|
|
potential"_pair_eam.html. The LAMMPS implementation is discussed in
|
|
|
|
"(Singh)"_#Singh. The total energy Ei of an atom I is given by
|
2011-06-09 04:56:17 +08:00
|
|
|
|
|
|
|
:c,image(Eqs/pair_adp.jpg)
|
|
|
|
|
|
|
|
where F is the embedding energy which is a function of the atomic
|
|
|
|
electron density rho, phi is a pair potential interaction, alpha and
|
|
|
|
beta are the element types of atoms I and J, and s and t = 1,2,3 and
|
|
|
|
refer to the cartesian coordinates. The mu and lambda terms represent
|
|
|
|
the dipole and quadruple distortions of the local atomic environment
|
|
|
|
which extend the original EAM framework by introducing angular forces.
|
|
|
|
|
|
|
|
Note that unlike for other potentials, cutoffs for ADP potentials are
|
|
|
|
not set in the pair_style or pair_coeff command; they are specified in
|
|
|
|
the ADP potential files themselves. Likewise, the ADP potential files
|
|
|
|
list atomic masses; thus you do not need to use the "mass"_mass.html
|
|
|
|
command to specify them.
|
|
|
|
|
|
|
|
The NIST WWW site distributes and documents ADP potentials:
|
|
|
|
|
|
|
|
http://www.ctcms.nist.gov/potentials :pre
|
|
|
|
|
|
|
|
Note that these must be converted into the extended DYNAMO {setfl}
|
|
|
|
format discussed below.
|
|
|
|
|
|
|
|
The NIST site is maintained by Chandler Becker (cbecker at nist.gov)
|
|
|
|
who is good resource for info on interatomic potentials and file
|
|
|
|
formats.
|
|
|
|
|
|
|
|
:line
|
|
|
|
|
|
|
|
Only a single pair_coeff command is used with the {adp} style which
|
|
|
|
specifies an extended DYNAMO {setfl} file, which contains information
|
|
|
|
for M elements. These are mapped to LAMMPS atom types by specifying N
|
|
|
|
additional arguments after the filename in the pair_coeff command,
|
|
|
|
where N is the number of LAMMPS atom types:
|
|
|
|
|
|
|
|
filename
|
|
|
|
N element names = mapping of extended {setfl} elements to atom types :ul
|
|
|
|
|
2013-06-29 01:19:51 +08:00
|
|
|
See the "pair_coeff"_pair_coeff.html doc page for alternate ways to
|
|
|
|
specify the path for the potential file.
|
|
|
|
|
2011-06-20 23:25:04 +08:00
|
|
|
As an example, the potentials/AlCu.adp file, included in the
|
|
|
|
potentials directory of the LAMMPS distrbution, is an extended {setfl}
|
2011-06-09 04:56:17 +08:00
|
|
|
file which has tabulated ADP values for w elements and their alloy
|
|
|
|
interactions: Cu and Al. If your LAMMPS simulation has 4 atoms types
|
|
|
|
and you want the 1st 3 to be Al, and the 4th to be Cu, you would use
|
|
|
|
the following pair_coeff command:
|
|
|
|
|
|
|
|
pair_coeff * * AlCu.adp Al Al Al Cu :pre
|
|
|
|
|
|
|
|
The 1st 2 arguments must be * * so as to span all LAMMPS atom types.
|
|
|
|
The first three Al arguments map LAMMPS atom types 1,2,3 to the Al
|
|
|
|
element in the extended {setfl} file. The final Cu argument maps
|
|
|
|
LAMMPS atom type 4 to the Al element in the extended {setfl} file.
|
|
|
|
Note that there is no requirement that your simulation use all the
|
|
|
|
elements specified by the extended {setfl} file.
|
|
|
|
|
|
|
|
If a mapping value is specified as NULL, the mapping is not performed.
|
|
|
|
This can be used when an {adp} potential is used as part of the
|
|
|
|
{hybrid} pair style. The NULL values are placeholders for atom types
|
|
|
|
that will be used with other potentials.
|
|
|
|
|
|
|
|
{Adp} files in the {potentials} directory of the LAMMPS distribution
|
|
|
|
have an ".adp" suffix. A DYNAMO {setfl} file extended for ADP is
|
|
|
|
formatted as follows. Basically it is the standard {setfl} format
|
|
|
|
with additional tabulated functions u and w added to the file after
|
|
|
|
the tabulated pair potentials. See the "pair_eam"_pair_eam.html
|
|
|
|
command for further details on the {setfl} format.
|
|
|
|
|
|
|
|
lines 1,2,3 = comments (ignored)
|
|
|
|
line 4: Nelements Element1 Element2 ... ElementN
|
|
|
|
line 5: Nrho, drho, Nr, dr, cutoff :ul
|
|
|
|
|
|
|
|
Following the 5 header lines are Nelements sections, one for each
|
|
|
|
element, each with the following format:
|
|
|
|
|
|
|
|
line 1 = atomic number, mass, lattice constant, lattice type (e.g. FCC)
|
|
|
|
embedding function F(rho) (Nrho values)
|
|
|
|
density function rho(r) (Nr values) :ul
|
|
|
|
|
|
|
|
Following the Nelements sections, Nr values for each pair potential
|
|
|
|
phi(r) array are listed for all i,j element pairs in the same format
|
|
|
|
as other arrays. Since these interactions are symmetric (i,j = j,i)
|
|
|
|
only phi arrays with i >= j are listed, in the following order: i,j =
|
|
|
|
(1,1), (2,1), (2,2), (3,1), (3,2), (3,3), (4,1), ..., (Nelements,
|
2012-04-20 22:26:22 +08:00
|
|
|
Nelements). The tabulated values for each phi function are listed as
|
|
|
|
r*phi (in units of eV-Angstroms), since they are for atom pairs, the
|
|
|
|
same as for "other EAM files"_pair_eam.html.
|
2011-06-09 04:56:17 +08:00
|
|
|
|
|
|
|
After the phi(r) arrays, each of the u(r) arrays are listed in the
|
|
|
|
same order with the same assumptions of symmetry. Directly following
|
2012-04-20 22:26:22 +08:00
|
|
|
the u(r), the w(r) arrays are listed. Note that phi(r) is the only
|
|
|
|
array tabulated with a scaling by r.
|
2011-06-09 04:56:17 +08:00
|
|
|
|
|
|
|
:line
|
|
|
|
|
2014-08-15 00:30:25 +08:00
|
|
|
Styles with a {cuda}, {gpu}, {intel}, {kk}, {omp}, or {opt} suffix are
|
|
|
|
functionally the same as the corresponding style without the suffix.
|
|
|
|
They have been optimized to run faster, depending on your available
|
|
|
|
hardware, as discussed in "Section_accelerate"_Section_accelerate.html
|
|
|
|
of the manual. The accelerated styles take the same arguments and
|
|
|
|
should produce the same results, except for round-off and precision
|
|
|
|
issues.
|
|
|
|
|
|
|
|
These accelerated styles are part of the USER-CUDA, GPU, USER-INTEL,
|
|
|
|
KOKKOS, USER-OMP and OPT packages, respectively. They are only
|
|
|
|
enabled if LAMMPS was built with those packages. See the "Making
|
|
|
|
LAMMPS"_Section_start.html#start_3 section for more info.
|
2011-10-07 01:32:51 +08:00
|
|
|
|
|
|
|
You can specify the accelerated styles explicitly in your input script
|
|
|
|
by including their suffix, or you can use the "-suffix command-line
|
2012-01-28 07:39:14 +08:00
|
|
|
switch"_Section_start.html#start_7 when you invoke LAMMPS, or you can
|
2011-10-07 01:32:51 +08:00
|
|
|
use the "suffix"_suffix.html command in your input script.
|
|
|
|
|
2011-12-14 04:35:35 +08:00
|
|
|
See "Section_accelerate"_Section_accelerate.html of the manual for
|
|
|
|
more instructions on how to use the accelerated styles effectively.
|
2011-10-07 01:32:51 +08:00
|
|
|
|
|
|
|
:line
|
|
|
|
|
2011-06-09 04:56:17 +08:00
|
|
|
[Mixing, shift, table, tail correction, restart, rRESPA info]:
|
|
|
|
|
|
|
|
For atom type pairs I,J and I != J, where types I and J correspond to
|
|
|
|
two different element types, no special mixing rules are needed, since
|
|
|
|
the ADP potential files specify alloy interactions explicitly.
|
|
|
|
|
|
|
|
This pair style does not support the "pair_modify"_pair_modify.html
|
|
|
|
shift, table, and tail options.
|
|
|
|
|
|
|
|
This pair style does not write its information to "binary restart
|
|
|
|
files"_restart.html, since it is stored in tabulated potential files.
|
|
|
|
Thus, you need to re-specify the pair_style and pair_coeff commands in
|
|
|
|
an input script that reads a restart file.
|
|
|
|
|
|
|
|
This pair style can only be used via the {pair} keyword of the
|
|
|
|
"run_style respa"_run_style.html command. It does not support the
|
|
|
|
{inner}, {middle}, {outer} keywords.
|
|
|
|
|
|
|
|
:line
|
|
|
|
|
|
|
|
[Restrictions:]
|
|
|
|
|
2011-08-27 02:53:00 +08:00
|
|
|
This pair style is part of the MANYBODY package. It is only enabled
|
2011-06-09 04:56:17 +08:00
|
|
|
if LAMMPS was built with that package (which it is by default).
|
|
|
|
|
|
|
|
[Related commands:]
|
|
|
|
|
|
|
|
"pair_coeff"_pair_coeff.html, "pair_eam"_pair_eam.html
|
|
|
|
|
|
|
|
[Default:] none
|
|
|
|
|
|
|
|
:line
|
|
|
|
|
2011-06-20 23:10:04 +08:00
|
|
|
:link(Mishin)
|
|
|
|
[(Mishin)] Mishin, Mehl, and Papaconstantopoulos, Acta Mater, 53, 4029
|
|
|
|
(2005).
|
|
|
|
|
|
|
|
:link(Singh)
|
|
|
|
[(Singh)] Singh and Warner, Acta Mater, 58, 5797-5805 (2010),
|