Surrogate Models
To speed up calculations, kawin supports the use of surrogate models on thermodynamic and kinetic calculations. The functions surrogate module are designed to be interchangeable with the corresponding functions in the thermodynamics module. For binary systems, surrogates can be made for driving forces, interfacial compositions and diffusivities. For multicomponent systems, surrogates can be made for driving forces and growth rates/interfacial compositions.
Creating a surrogate model involves sampling a set of points (
The surrogate module in kawin relies on radial basis functions (
Gaussian:
Multiquadric:
Inverse multiquadric:
Polynomial:
Given
Where the weights are found from the training samples.
In practice, kawin will scale the position of the samples so the average distance between each point is around 1. In addition, the composition inputs and outputs may be transformed to a logarithmic form, which can be necessary for dilute solutions.