forked from lijiext/lammps
96 lines
3.4 KiB
Plaintext
96 lines
3.4 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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bond_coeff command :h3
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[Syntax:]
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bond_coeff N args :pre
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N = bond type (see asterisk form below)
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args = coefficients for one or more bond types :ul
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[Examples:]
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bond_coeff 5 80.0 1.2
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bond_coeff * 30.0 1.5 1.0 1.0
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bond_coeff 1*4 30.0 1.5 1.0 1.0
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bond_coeff 1 harmonic 200.0 1.0 :pre
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[Description:]
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Specify the bond force field coefficients for one or more bond types.
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The number and meaning of the coefficients depends on the bond style.
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Bond coefficients can also be set in the data file read by the
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"read_data"_read_data.html command or in a restart file.
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N can be specified in one of two ways. An explicit numeric value can
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be used, as in the 1st example above. Or a wild-card asterisk can be
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used to set the coefficients for multiple bond types. This takes the
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form "*" or "*n" or "n*" or "m*n". If N = the number of bond types,
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then an asterisk with no numeric values means all types from 1 to N. A
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leading asterisk means all types from 1 to n (inclusive). A trailing
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asterisk means all types from n to N (inclusive). A middle asterisk
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means all types from m to n (inclusive).
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Note that using a bond_coeff command can override a previous setting
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for the same bond type. For example, these commands set the coeffs
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for all bond types, then overwrite the coeffs for just bond type 2:
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bond_coeff * 100.0 1.2
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bond_coeff 2 200.0 1.2 :pre
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A line in a data file that specifies bond coefficients uses the exact
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same format as the arguments of the bond_coeff command in an input
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script, except that wild-card asterisks should not be used since
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coefficients for all N types must be listed in the file. For example,
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under the "Bond Coeffs" section of a data file, the line that
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corresponds to the 1st example above would be listed as
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5 80.0 1.2 :pre
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:line
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Here is an alphabetic list of bond styles defined in LAMMPS. Click on
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the style to display the formula it computes and coefficients
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specified by the associated "bond_coeff"_bond_coeff.html command:
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"bond_style none"_bond_none.html - turn off bonded interactions
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"bond_style hybrid"_bond_hybrid.html - define multiple styles of bond interactions :ul
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"bond_style class2"_bond_class2.html - COMPASS (class 2) bond
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"bond_style fene"_bond_fene.html - FENE (finite-extensible non-linear elastic) bond
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"bond_style fene/expand"_bond_fene_expand.html - FENE bonds with variable size particles
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"bond_style harmonic"_bond_harmonic.html - harmonic bond
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"bond_style morse"_bond_morse.html - Morse bond
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"bond_style nonlinear"_bond_nonlinear.html - nonlinear bond
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"bond_style quartic"_bond_quartic.html - breakable quartic bond
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"bond_style table"_bond_table.html - tabulated by bond length :ul
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There are also additional bond styles submitted by users which are
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included in the LAMMPS distribution. The list of these with links to
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the individual styles are given in the bond section of "this
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page"_Section_commands.html#cmd_5.
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:line
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[Restrictions:]
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This command must come after the simulation box is defined by a
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"read_data"_read_data.html, "read_restart"_read_restart.html, or
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"create_box"_create_box.html command.
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A bond style must be defined before any bond coefficients are set,
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either in the input script or in a data file.
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[Related commands:]
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"bond_style"_bond_style.html
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[Default:] none
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