improper_style sqdistharm command


improper_style sqdistharm


improper_style sqdistharm
improper_coeff 1 50.0 0.1


The sqdistharm improper style uses the potential


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 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)

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


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