forked from lijiext/lammps
65 lines
1.7 KiB
Plaintext
65 lines
1.7 KiB
Plaintext
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"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_style cosine/periodic command :h3
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[Syntax:]
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angle_style cosine/periodic :pre
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[Examples:]
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angle_style cosine/periodic
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angle_coeff * 75.0 1 6 :pre
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[Description:]
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The {cosine/periodic} angle style uses the following potential, which
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is commonly used in the "DREIDING"_Section_howto.html#4_4 force field,
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particularly for organometallic systems where {n} = 4 might be used
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for an octahedral complex and {n} = 3 might be used for a trigonal
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center:
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:c,image(Eqs/angle_cosine_periodic.jpg)
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where C, B and n are coefficients defined for each angle type.
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See "(Mayo)"_#Mayo for a description of the DREIDING force field
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The following coefficients must be defined for each angle type via the
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"angle_coeff"_angle_coeff.html command as in the example above, or in
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the data file or restart files read by the "read_data"_read_data.html
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or "read_restart"_read_restart.html commands:
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C (energy)
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B = 1 or -1
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n = 1, 2, 3, 4, 5 or 6 for periodicity :ul
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Note that the prefactor C is specified and not the overall force
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constant K = C / n^2. When B = 1, it leads to a minimum for the
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linear geometry. When B = -1, it leads to a maximum for the linear
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geometry.
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[Restrictions:]
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This angle style can only be used if LAMMPS was built with the
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"molecular" package (which it is by default). See the "Making
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LAMMPS"_Section_start.html#2_3 section for more info on packages.
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[Related commands:]
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"angle_coeff"_angle_coeff.html
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[Default:] none
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:line
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:link(Mayo)
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[(Mayo)] Mayo, Olfason, Goddard III, J Phys Chem, 94, 8897-8909
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(1990).
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