# gran surface superquadric model

## Syntax

    surface superquadric [other model_type/model_name pairs as described here ] keyword values

- zero or more keyword/value pairs may be appended to the end (after all models are specified)

    curvatureLimitFactor values = more or equal 0
    gaussianCurvature values = yes or no
    meanCurvature values = yes or no

## Description

This is the surface model for smooth convex superquadric particles. For contact detection and force calculation algorithms see Podlozhnyuk et al (2017). Calculation of particle radius R1 and R2 in Hertz or Hooke model is based on mean or gaussian curvature radius at a contact point. The effective radius R* is limited by the factor of curvatureLimitFactor with respect to R* calculated using R1 and R2 as volume equivalent radii. If curvatureLimitFactor=0 particle radii R1 and R2 are volume equivalent radii that don’t depend on the contact point.

This model is used in the framework of SUPERQUADRIC simulations. For more information see also the `SUPERQUADRIC guide`.

## Restrictions

> requires atom_style superquadric.

meanCurvature and gaussianCurvature cannot be simultaneously yes

Coarse-graining information:

Using `coarsegraining` in combination with this command might lead to statistically different dynamics and system state. To the best knowledge of the developers, the cross-influence between this command and coarse-graining is unknown.

## Default

curvatureLimitFactor = 0

gaussianCurvature = ‘no’

meanCurvature = ‘no’

(Podlozhnyuk et al.) A.Podlozhnyuk, S.Pirker, C.Kloss, J.Comp.Part.Mech, 4 (1), p 1-18 (2017).