forked from lijiext/lammps
100 lines
3.6 KiB
Plaintext
100 lines
3.6 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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angle_coeff command :h3
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[Syntax:]
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angle_coeff N args :pre
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N = angle type (see asterisk form below)
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args = coefficients for one or more angle types :ul
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[Examples:]
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angle_coeff 1 300.0 107.0
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angle_coeff * 5.0
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angle_coeff 2*10 5.0 :pre
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[Description:]
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Specify the angle force field coefficients for one or more angle types.
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The number and meaning of the coefficients depends on the angle style.
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Angle 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 angle types. This takes the
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form "*" or "*n" or "n*" or "m*n". If N = the number of angle 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 an angle_coeff command can override a previous setting
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for the same angle type. For example, these commands set the coeffs
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for all angle types, then overwrite the coeffs for just angle type 2:
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angle_coeff * 200.0 107.0 1.2
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angle_coeff 2 50.0 107.0 :pre
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A line in a data file that specifies angle coefficients uses the exact
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same format as the arguments of the angle_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 "Angle 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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1 300.0 107.0 :pre
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The "angle_style class2"_angle_class2.html is an exception to this
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rule, in that an additional argument is used in the input script to
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allow specification of the cross-term coefficients. See its
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doc page for details.
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:line
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Here is an alphabetic list of angle 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 "angle_coeff"_angle_coeff.html command:
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"angle_style none"_angle_none.html - turn off angle interactions
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"angle_style hybrid"_angle_hybrid.html - define multiple styles of angle interactions :ul
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"angle_style charmm"_angle_charmm.html - CHARMM angle
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"angle_style class2"_angle_class2.html - COMPASS (class 2) angle
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"angle_style cosine"_angle_cosine.html - cosine angle potential
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"angle_style cosine/delta"_angle_cosine_delta.html - difference of cosines angle potential
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"angle_style cosine/periodic"_angle_cosine_periodic.html - DREIDING angle
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"angle_style cosine/squared"_angle_cosine_squared.html - cosine squared angle potential
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"angle_style harmonic"_angle_harmonic.html - harmonic angle
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"angle_style table"_angle_table.html - tabulated by angle :ul
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There are also additional angle 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 angle section of "this
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page"_Section_commands.html#3_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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An angle style must be defined before any angle coefficients are
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set, either in the input script or in a data file.
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[Related commands:]
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"angle_style"_angle_style.html
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[Default:] none
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