improper_style fourier command

Accelerator Variants: fourier/omp


improper_style fourier


improper_style fourier
improper_coeff 1 100.0 0.0 1.0 0.5 1


The fourier improper style uses the following potential:

\[E = K [C_0 + C_1 \cos ( \omega) + C_2 \cos( 2 \omega) ]\]

where K is the force constant, C0, C1, C2 are dimensionless coefficients, and omega is the angle between the IL axis and the IJK plane:


If all parameter (see below) is not zero, the all the three possible angles will taken in account.

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)

  • \(C_0\) (unitless)

  • \(C_1\) (unitless)

  • \(C_2\) (unitless)

  • all (0 or 1, optional)

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 on the Accelerator packages page. 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, INTEL, KOKKOS, OPENMP, and OPT packages, respectively. They are only enabled if LAMMPS was built with those packages. See the Build package page 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 when you invoke LAMMPS, or you can use the suffix command in your input script.

See the Accelerator packages page for more instructions on how to use the accelerated styles effectively.


This angle style can only be used if LAMMPS was built with the MOLECULE package. See the Build package doc page for more info.