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lammps/doc/src/dihedral_helix.txt
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"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c
:link(lws,http://lammps.sandia.gov)
:link(ld,Manual.html)
:link(lc,Section_commands.html#comm)
:line
dihedral_style helix command :h3
dihedral_style helix/omp command :h3
[Syntax:]
dihedral_style helix :pre
[Examples:]
dihedral_style helix
dihedral_coeff 1 80.0 100.0 40.0 :pre
[Description:]
The {helix} dihedral style uses the potential
:c,image(Eqs/dihedral_helix.jpg)
This coarse-grain dihedral potential is described in "(Guo)"_#Guo.
For dihedral angles in the helical region, the energy function is
represented by a standard potential consisting of three minima, one
corresponding to the trans (t) state and the other to gauche states
(g+ and g-). The paper describes how the A,B,C parameters are chosen
so as to balance secondary (largely driven by local interactions) and
tertiary structure (driven by long-range interactions).
The following coefficients must be defined for each dihedral type via the
"dihedral_coeff"_dihedral_coeff.html command as in the example above, or in
the data file or restart files read by the "read_data"_read_data.html
or "read_restart"_read_restart.html commands:
A (energy)
B (energy)
C (energy) :ul
:line
Styles with a {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 "Section_accelerate"_Section_accelerate.html
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 GPU, USER-INTEL, KOKKOS,
USER-OMP and OPT packages, respectively. They are only enabled if
LAMMPS was built with those packages. See the "Making
LAMMPS"_Section_start.html#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 "-suffix command-line
switch"_Section_start.html#start_7 when you invoke LAMMPS, or you can
use the "suffix"_suffix.html command in your input script.
See "Section_accelerate"_Section_accelerate.html of the manual for
more instructions on how to use the accelerated styles effectively.
:line
[Restrictions:]
This dihedral style can only be used if LAMMPS was built with the
MOLECULE package (which it is by default). See the "Making
LAMMPS"_Section_start.html#start_3 section for more info on packages.
[Related commands:]
"dihedral_coeff"_dihedral_coeff.html
[Default:] none
:line
:link(Guo)
[(Guo)] Guo and Thirumalai, Journal of Molecular Biology, 263, 323-43 (1996).
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