git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@14950 f3b2605a-c512-4ea7-a41b-209d697bcdaa

doc/html/_sources/pair_zbl.txt

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+.. index:: pair_style zbl
+
+pair_style zbl command
+======================
+
+pair_style zbl/gpu command
+==========================
+
+pair_style zbl/omp command
+==========================
+
+Syntax
+""""""
+
+.. parsed-literal::
+
+   pair_style zbl inner outer
+
+* inner = distance where switching function begins
+* outer = global cutoff for ZBL interaction
+
+Examples
+""""""""
+
+.. parsed-literal::
+
+   pair_style zbl 3.0 4.0
+   pair_coeff * * 73.0 73.0
+   pair_coeff 1 1 14.0 14.0
+
+Description
+"""""""""""
+
+Style *zbl* computes the Ziegler-Biersack-Littmark (ZBL) screened nuclear
+repulsion for describing high-energy collisions between atoms.
+:ref:`(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:
+
+.. image:: Eqs/pair_zbl.jpg
+   :align: center
+
+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
+:doc:`pair_style lj/gromacs <pair_gromacs>`.  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 :doc:`pair_coeff <pair_coeff>` 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)
+
+* Z_j (ditto for second atom type)
+
+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 :doc:`hybrid/overlay <pair_hybrid>` 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.
+
+.. 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 :doc:`units <units>` setting.  The values of Z should
+   always be given as multiples of a proton's charge, e.g. 29.0 for
+   copper.
+
+
+----------
+
+
+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 :doc:`Section_accelerate <Section_accelerate>`
+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 :ref:`Making LAMMPS <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 :ref:`-suffix command-line switch <start_7>` when you invoke LAMMPS, or you can
+use the :doc:`suffix <suffix>` command in your input script.
+
+See :doc:`Section_accelerate <Section_accelerate>` of the manual for
+more instructions on how to use the accelerated styles effectively.
+
+
+----------
+
+
+**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 :doc:`hybrid/overlay <pair_hybrid>` 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 :doc:`pair_modify <pair_modify>` mix option has no effect on
+the mixing behavior
+
+The ZBL pair style does not support the :doc:`pair_modify <pair_modify>`
+shift option, since the ZBL interaction is already smoothed to 0.0 at
+the cutoff.
+
+The :doc:`pair_modify <pair_modify>` table option is not relevant for
+this pair style.
+
+This pair style does not support the :doc:`pair_modify <pair_modify>`
+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 :doc:`binary restart files <restart>`, 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
+:doc:`run_style respa <run_style>` command.  It does not support the
+*inner*\ , *middle*\ , *outer* keywords.
+
+
+----------
+
+
+Restrictions
+""""""""""""
+ none
+
+Related commands
+""""""""""""""""
+
+:doc:`pair_coeff <pair_coeff>`
+
+**Default:** none
+
+
+----------
+
+
+.. _Ziegler:
+
+
+
+**(Ziegler)** J.F. Ziegler, J. P. Biersack and U. Littmark, "The
+Stopping and Range of Ions in Matter," Volume 1, Pergamon, 1985.
+
+
+.. _lws: http://lammps.sandia.gov
+.. _ld: Manual.html
+.. _lc: Section_commands.html#comm