Geometric Models 

#include <psGeometricDistributionModels.hpp>

Geometric models apply purely geometric transformations to the surface, independent of any particle fluxes or surface chemistry. They are typically used to quickly emulate processes such as isotropic or anisotropic etching and deposition.

Each geometric model is defined by a surface distribution function, which specifies how the processed surface is constructed. For instance, an isotropic deposition model uses a spherical distribution of constant radius: a sphere is centered at every surface point, and the outermost envelope of all spheres forms the new surface after deposition.

Anisotropic behavior can be introduced by using non-spherical or directional distributions, such as box-shaped or custom-defined ones. ViennaPS provides three ready-to-use geometric distributions:

  • SphereDistribution — for isotropic processes
  • BoxDistribution — for directional or anisotropic processes
  • CustomSphereDistribution — for user-defined spherical variants

These models can be applied directly as ProcessModelCPU objects within a Process.

Sphere Distribution

Creates an isotropic geometric model using spherical envelopes of constant radius. Each surface point is expanded into a sphere of radius r, and the new surface is formed by the outermost boundary of all spheres.

Constructor:

SphereDistribution(NumericType radius, LSPtr mask = nullptr)

Parameters:

Name Type Description
radius NumericType Radius of the spherical distribution (controls isotropic expansion or shrinkage).
mask SmartPointer<viennals::Domain<NumericType, D>> (optional) Optional mask layer that restricts the process to specific regions.

Box Distribution

Creates an anisotropic geometric model based on box-shaped envelopes. Each surface point is expanded by a rectangular box defined by its half-axis lengths, allowing directional or anisotropic effects.

Constructor:

BoxDistribution(const std::array<viennahrle::CoordType, 3> &halfAxes,
                LSPtr mask = nullptr)

Parameters:

Name Type Description
halfAxes std::array<double, 3> Half-axis lengths of the box distribution in x, y, and z directions.
mask SmartPointer<viennals::Domain<NumericType, D>> (optional) Optional mask layer to confine processing.

Custom Sphere Distribution

Defines a custom isotropic model where the radius of the spherical distribution varies for each surface point. Each surface point uses the corresponding radius from the provided list. Surface points can be extracted by using the ToDiskMesh utility.

Constructor:

CustomSphereDistribution(const std::vector<NumericType> &radii,
                         LSPtr mask = nullptr)

Parameters:

Name Type Description
radii std::vector<NumericType> List of radii for each surface point.
mask SmartPointer<viennals::Domain<NumericType, D>> (optional) Optional mask restricting which surface regions are processed.

Each of these models can be used as input to a Process object:

auto model = SmartPointer<SphereDistribution<double, 3>>(1.0);
Process(domain, model, time).apply();