forked from lijiext/lammps
87 lines
2.7 KiB
Plaintext
87 lines
2.7 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,Commands_all.html)
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:line
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improper_style cvff command :h3
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improper_style cvff/intel command :h3
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improper_style cvff/omp command :h3
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[Syntax:]
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improper_style cvff :pre
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[Examples:]
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improper_style cvff
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improper_coeff 1 80.0 -1 4 :pre
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[Description:]
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The {cvff} improper style uses the potential
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:c,image(Eqs/improper_cvff.jpg)
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where phi is the improper dihedral angle.
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If the 4 atoms in an improper quadruplet (listed in the data file read
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by the "read_data"_read_data.html command) are ordered I,J,K,L then
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the improper dihedral angle is between the plane of I,J,K and the
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plane of J,K,L. Note that because this is effectively a dihedral
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angle, the formula for this improper style is the same as for
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"dihedral_style harmonic"_dihedral_harmonic.html.
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Note that defining 4 atoms to interact in this way, does not mean that
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bonds necessarily exist between I-J, J-K, or K-L, as they would in a
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linear dihedral. Normally, the bonds I-J, I-K, I-L would exist for an
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improper to be defined between the 4 atoms.
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The following coefficients must be defined for each improper type via
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the "improper_coeff"_improper_coeff.html command as in the example
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above, or in the data file or restart files read by the
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"read_data"_read_data.html or "read_restart"_read_restart.html
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commands:
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K (energy)
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d (+1 or -1)
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n (0,1,2,3,4,6) :ul
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:line
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Styles with a {gpu}, {intel}, {kk}, {omp}, or {opt} suffix are
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functionally the same as the corresponding style without the suffix.
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They have been optimized to run faster, depending on your available
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hardware, as discussed on the "Speed packages"_Speed_packages.html doc
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page. 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 GPU, USER-INTEL, KOKKOS,
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USER-OMP and OPT packages, respectively. They are only enabled if
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LAMMPS was built with those packages. See the "Build
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package"_Build_package.html doc page 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"_Run_options.html when you invoke LAMMPS, or you can use the
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"suffix"_suffix.html command in your input script.
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See the "Speed packages"_Speed_packages.html doc page for more
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instructions on how to use the accelerated styles effectively.
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:line
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[Restrictions:]
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This improper style can only be used if LAMMPS was built with the
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MOLECULE package. See the "Build package"_Build_package.html doc page
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for more info.
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[Related commands:]
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"improper_coeff"_improper_coeff.html
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[Default:] none
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