"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c

:link(lws,http://lammps.sandia.gov)
:link(ld,Manual.html)
:link(lc,Commands_all.html)

:line

improper_style sqdistharm command :h3

[Syntax:]

improper_style sqdistharm

[Examples:]

improper_style sqdistharm
improper_coeff 1 50.0 0.1 :pre

[Description:]

The {sqdistharm} improper style uses the potential

:c,image(Eqs/improper_sqdistharm.jpg)

where d is the distance between the central atom and the plane formed
by the other three atoms.  If the 4 atoms in an improper quadruplet
(listed in the data file read by the "read_data"_read_data.html
command) are ordered I,J,K,L then the L-atom is assumed to be the
central atom. Note that this is different from the convention used
in the improper_style distance.

The following coefficients must be defined for each improper type via
the improper_coeff command as in the example above, or in the data
file or restart files read by the read_data or read_restart commands:

K (energy/distance^4)
d0^2 (distance^2) :ul

Note that d0^2 (in units distance^2) has be provided and not d0.

:line

[Restrictions:]

This improper style can only be used if LAMMPS was built with the
USER-MISC package.  See the "Build package"_Build_package.html doc
page for more info.

[Related commands:]

"improper_coeff"_improper_coeff.html

[Default:] none
