# angle_style sdk/omp command

## Syntax

angle_style sdk

angle_style sdk/omp


## Examples

angle_style sdk
angle_coeff 1 300.0 107.0


## Description

The sdk angle style is a combination of the harmonic angle potential,

$E = K (\theta - \theta_0)^2$

where $$\theta_0$$ is the equilibrium value of the angle and $$K$$ a prefactor, with the repulsive part of the non-bonded lj/sdk pair style between the atoms 1 and 3. This angle potential is intended for coarse grained MD simulations with the CMM parameterization using the pair_style lj/sdk. Relative to the pair_style lj/sdk, however, the energy is shifted by $$\epsilon$$, to avoid sudden jumps. Note that the usual 1/2 factor is included in $$K$$.

The following coefficients must be defined for each angle type via the angle_coeff command as in the example above:

• $$K$$ (energy/radian^2)

• $$\theta_0$$ (degrees)

$$\theta_0$$ is specified in degrees, but LAMMPS converts it to radians internally; hence the units of $$K$$ are in energy/radian^2. The also required lj/sdk parameters will be extracted automatically from the pair_style.

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 Speed packages doc 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, USER-INTEL, KOKKOS, USER-OMP and OPT packages, respectively. They are only enabled if LAMMPS was built with those packages. See the Build package doc 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 Speed packages doc page for more instructions on how to use the accelerated styles effectively.

## Restrictions

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