forked from lijiext/lammps
140 lines
5.0 KiB
Plaintext
140 lines
5.0 KiB
Plaintext
"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 zbl command :h3
|
|
pair_style zbl/gpu command :h3
|
|
pair_style zbl/omp command :h3
|
|
|
|
[Syntax:]
|
|
|
|
pair_style zbl inner outer :pre
|
|
|
|
inner = distance where switching function begins
|
|
outer = global cutoff for ZBL interaction :ul
|
|
|
|
[Examples:]
|
|
|
|
pair_style zbl 3.0 4.0
|
|
pair_coeff * * 73.0 73.0
|
|
pair_coeff 1 1 14.0 14.0 :pre
|
|
|
|
[Description:]
|
|
|
|
Style {zbl} computes the Ziegler-Biersack-Littmark (ZBL) screened nuclear
|
|
repulsion for describing high-energy collisions between atoms.
|
|
"(Ziegler)"_#Ziegler. It includes an additional switching function
|
|
that ramps the energy, force, and curvature smoothly to zero
|
|
between an inner and outer cutoff. The potential
|
|
energy due to a pair of atoms at a distance r_ij is given by:
|
|
|
|
:c,image(Eqs/pair_zbl.jpg)
|
|
|
|
where e is the electron charge, epsilon_0 is the electrical
|
|
permittivity of vacuum, and Z_i and Z_j are the nuclear charges of the
|
|
two atoms. The switching function S(r) is identical to that used by
|
|
"pair_style lj/gromacs"_pair_gromacs.html. Here, the inner and outer
|
|
cutoff are the same for all pairs of atom types.
|
|
|
|
The following coefficients must be defined for each pair of atom types
|
|
via the "pair_coeff"_pair_coeff.html command as in the examples above,
|
|
or in the LAMMPS data file.
|
|
|
|
Z_i (atomic number for first atom type, e.g. 13.0 for aluminum) :ul
|
|
Z_j (ditto for second atom type) :ul
|
|
|
|
The values of Z_i and Z_j are normally equal to the atomic
|
|
numbers of the two atom types. Thus, the user may optionally
|
|
specify only the coefficients for each I==I pair, and rely
|
|
on the obvious mixing rule for cross interactions (see below).
|
|
Note that when I==I it is required that Z_i == Z_j. When used
|
|
with "hybrid/overlay"_pair_hybrid.html and pairs are assigned
|
|
to more than one sub-style, the mixing rule is not used and
|
|
each pair of types interacting with the ZBL sub-style must
|
|
be included in a pair_coeff command.
|
|
|
|
IMPORTANT NOTE: The numerical values of the exponential decay
|
|
constants in the screening function depend on the unit of distance. In
|
|
the above equation they are given for units of angstroms. LAMMPS will
|
|
automatically convert these values to the distance unit of the
|
|
specified LAMMPS "units"_units.html setting. The values of Z should
|
|
always be given as multiples of a proton's charge, e.g. 29.0 for
|
|
copper.
|
|
|
|
:line
|
|
|
|
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.
|
|
|
|
You can specify the accelerated styles explicitly in your input script
|
|
by including their suffix, or you can use the "-suffix command-line
|
|
switch"_Section_start.html#start_7 when you invoke LAMMPS, or you can
|
|
use the "suffix"_suffix.html command in your input script.
|
|
|
|
See "Section_accelerate"_Section_accelerate.html of the manual for
|
|
more instructions on how to use the accelerated styles effectively.
|
|
|
|
:line
|
|
|
|
[Mixing, shift, table, tail correction, restart, rRESPA info]:
|
|
|
|
For atom type pairs I,J and I != J, the Z_i and Z_j coefficients
|
|
can be mixed by taking Z_i and Z_j from the values specified for
|
|
I == I and J == J cases. When used
|
|
with "hybrid/overlay"_pair_hybrid.html and pairs are assigned
|
|
to more than one sub-style, the mixing rule is not used and
|
|
each pair of types interacting with the ZBL sub-style
|
|
must be included in a pair_coeff command.
|
|
The "pair_modify"_pair_modify.html mix option has no effect on
|
|
the mixing behavior
|
|
|
|
The ZBL pair style does not support the "pair_modify"_pair_modify.html
|
|
shift option, since the ZBL interaction is already smoothed to 0.0 at
|
|
the cutoff.
|
|
|
|
The "pair_modify"_pair_modify.html table option is not relevant for
|
|
this pair style.
|
|
|
|
This pair style does not support the "pair_modify"_pair_modify.html
|
|
tail option for adding long-range tail corrections to energy and
|
|
pressure, since there are no corrections for a potential that goes to
|
|
0.0 at the cutoff.
|
|
|
|
This pair style does not write information to "binary restart
|
|
files"_restart.html, so pair_style and pair_coeff commands must be
|
|
specified 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:] none
|
|
|
|
[Related commands:]
|
|
|
|
"pair_coeff"_pair_coeff.html
|
|
|
|
[Default:] none
|
|
|
|
:line
|
|
|
|
:link(Ziegler)
|
|
[(Ziegler)] J.F. Ziegler, J. P. Biersack and U. Littmark, "The
|
|
Stopping and Range of Ions in Matter," Volume 1, Pergamon, 1985.
|