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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
pair_style gauss command :h3
pair_style gauss/gpu command :h3
pair_style gauss/omp command :h3
pair_style gauss/cut command :h3
pair_style gauss/cut/omp command :h3
[Syntax:]
pair_style gauss cutoff
pair_style gauss/cut cutoff :pre
cutoff = global cutoff for Gauss interactions (distance units) :ul
[Examples:]
pair_style gauss 12.0
pair_coeff * * 1.0 0.9
pair_coeff 1 4 1.0 0.9 10.0 :pre
pair_style gauss/cut 3.5
pair_coeff 1 4 0.2805 1.45 0.112 :pre
[Description:]
Style {gauss} computes a tethering potential of the form
:c,image(Eqs/pair_gauss.jpg)
between an atom and its corresponding tether site which will typically
be a frozen atom in the simulation. Rc is the cutoff.
The following coefficients must be defined for each pair of atom types
via the "pair_coeff"_pair_coeff.html command as in the examples 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 units)
B (1/distance^2 units)
cutoff (distance units) :ul
The last coefficient is optional. If not specified, the global cutoff
is used.
Style {gauss/cut} computes a generalized Gaussian interaction potential
between pairs of particles:
:c,image(Eqs/pair_gauss_cut.jpg)
where H determines together with the standard deviation sigma_h the
peak height of the Gaussian function, and r_mh the peak position.
Examples of the use of the Gaussian potentials include implicit
solvent simulations of salt ions "(Lenart)"_#Lenart and of surfactants
"(Jusufi)"_#Jusufi. In these instances the Gaussian potential mimics
the hydration barrier between a pair of particles. The hydration
barrier is located at r_mh and has a width of sigma_h. The prefactor
determines the hight of the potential barrier.
The following coefficients must be defined for each pair of atom types
via the "pair_coeff"_pair_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:
H (energy * distance units)
r_mh (distance units)
sigma_h (distance units) :ul
The global cutoff (r_c) specified in the pair_style command is used.
: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
switch7_Section_start.html#start_6 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
[Mixing, shift, table, tail correction, restart, rRESPA info]:
These pair styles do not support mixing. Thus, coefficients for all
I,J pairs must be specified explicitly.
The {gauss} style does not support the "pair_modify"_pair_modify.html
shift option. There is no effect due to the Gaussian well beyond the
cutoff; hence reasonable cutoffs need to be specified.
The {gauss/cut} style supports the "pair_modify"_pair_modify.html shift
option for the energy of the Gauss-potential portion of the pair
interaction.
The "pair_modify"_pair_modify.html table and tail options are not
relevant for these pair styles.
These pair styles write their information to "binary restart
files"_restart.html, so pair_style and pair_coeff commands do not need
to be specified in an input script that reads a restart file.
These pair styles can only be used via the {pair} keyword of the
"run_style respa"_run_style.html command. They do not support the
{inner}, {middle}, {outer} keywords.
The {gauss} pair style tallies an "occupancy" count of how many Gaussian-well
sites have an atom within the distance at which the force is a maximum
= sqrt(0.5/b). This quantity can be accessed via the "compute
pair"_compute_pair.html command as a vector of values of length 1.
To print this quantity to the log file (with a descriptive column
heading) the following commands could be included in an input script:
compute gauss all pair gauss
variable occ equal c_gauss\[1\]
thermo_style custom step temp epair v_occ :pre
:line
[Restrictions:]
The {gauss/cut} style is part of the "user-misc" package. It is only
enabled if LAMMPS is build with that package. See the "Making of
LAMMPS"_Section_start.html#start_3 section for more info.
[Related commands:]
"pair_coeff"_pair_coeff.html,
"pair_style coul/diel"_pair_coul_diel.html
[Default:] none
:link(Lenart)
[(Lenart)] Lenart , Jusufi, and Panagiotopoulos, J Chem Phys, 126,
044509 (2007).
:link(Jusufi)
[(Jusufi)] Jusufi, Hynninen, and Panagiotopoulos, J Phys Chem B, 112,
13783 (2008).
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