forked from lijiext/lammps
130 lines
4.4 KiB
Plaintext
130 lines
4.4 KiB
Plaintext
"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c
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:link(lws,http://lammps.sandia.gov)
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:link(ld,Manual.html)
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:link(lc,Section_commands.html#comm)
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:line
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pair_style zbl command :h3
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pair_style zbl/omp command :h3
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[Syntax:]
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pair_style zbl inner outer :pre
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inner = distance where switching function begins
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outer = global cutoff for ZBL interaction :ul
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[Examples:]
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pair_style zbl 3.0 4.0
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pair_coeff * * 73.0
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pair_coeff 1 1 14.0 :pre
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[Description:]
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Style {zbl} computes the Ziegler-Biersack-Littmark (ZBL) screened nuclear
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repulsion for describing high-energy collisions between atoms.
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"(Ziegler)"_#Ziegler. It includes an additional switching function
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that ramps the energy, force, and curvature smoothly to zero
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between an inner and outer cutoff. The potential
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energy due to a pair of atoms at a distance r_ij is given by:
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:c,image(Eqs/pair_zbl.jpg)
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where e is the electron
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charge, epsilon_0 is the electrical permittivity of vacuum, and
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Z_i and Z_j are the nuclear charges of the two atoms in electron
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charge units.
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The switching
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function S(r) is identical to that used by
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"pair_style lj/gromacs"_pair_gromacs.html.
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Here, the inner and outer cutoff are the same
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for all pairs of atom types.
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The following coefficient must be defined for each pair of atom types
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via the "pair_coeff"_pair_coeff.html command as in the examples above,
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or in the LAMMPS data file.
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Z can not be specified for two different atoms types.
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Therefore the lists of atom types I and atom types J must match.
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Z (electron charge) :ul
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Although Z must be defined for all atom type pairs I,J, it is only
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stored for individual atom types, i.e. when I = J. Z is normally equal
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to the atomic number of the atom type.
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IMPORTANT NOTE: The numerical values of the exponential decay
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constants in the screening function depend on the unit of distance. In
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the above equation they are given for units of angstroms. LAMMPS will
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automatically convert these values to the distance unit of the
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specified LAMMPS "units"_units.html setting. The values of Z should
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always be given in units of electron charge.
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:line
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Styles with a {cuda}, {gpu}, {omp}, or {opt} suffix are functionally
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the same as the corresponding style without the suffix. They have
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been optimized to run faster, depending on your available hardware, as
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discussed in "Section_accelerate"_Section_accelerate.html of the
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manual. The accelerated styles take the same arguments and should
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produce the same results, except for round-off and precision issues.
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These accelerated styles are part of the USER-CUDA, GPU, USER-OMP and OPT
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packages, respectively. They are only enabled if LAMMPS was built with
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those packages. See the "Making LAMMPS"_Section_start.html#start_3
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section for more info.
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You can specify the accelerated styles explicitly in your input script
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by including their suffix, or you can use the "-suffix command-line
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switch"_Section_start.html#start_7 when you invoke LAMMPS, or you can
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use the "suffix"_suffix.html command in your input script.
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See "Section_accelerate"_Section_accelerate.html of the manual for
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more instructions on how to use the accelerated styles effectively.
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:line
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[Mixing, shift, table, tail correction, restart, rRESPA info]:
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Mixing is not relevant for this pair style, since as explained above,
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Z values are stored on a per-type basis, and both Zi and Zj are used
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explicitly in the ZBL formula.
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The ZBL pair style does not support the "pair_modify"_pair_modify.html
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shift option, since the ZBL interaction is already smoothed to 0.0 at
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the cutoff.
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The "pair_modify"_pair_modify.html table option is not relevant for
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this pair style.
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This pair style does not support the "pair_modify"_pair_modify.html
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tail option for adding long-range tail corrections to energy and
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pressure, since there are no corrections for a potential that goes to
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0.0 at the cutoff.
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This pair style does not write information to "binary restart
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files"_restart.html, so pair_style and pair_coeff commands must be
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specified in an input script that reads a restart file.
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This pair style can only be used via the {pair} keyword of the
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"run_style respa"_run_style.html command. It does not support the
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{inner}, {middle}, {outer} keywords.
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:line
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[Restrictions:] none
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[Related commands:]
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"pair_coeff"_pair_coeff.html
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[Default:] none
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:line
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:link(Ziegler)
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[(Ziegler)] J.F. Ziegler, J. P. Biersack and U. Littmark, "The
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Stopping and Range of Ions in Matter," Volume 1, Pergamon, 1985.
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