RadDiagram supports force layout algorithm which is explained in this article.
The Force-directed layout algorithm (also known as the spring-embedded algorithm) is based on a physical simulation of forces acting on the nodes whereby the links define whether two nodes act upon each other. Each link effectively is like a spring embedded in the diagram. The simulation attempts to find a minimum energy state in such a way that the springsare in their base-state and thus do not pull or push any (linked) node. This force-directed layout is non-deterministic; each layout pass will result in an unpredictable (and hence not reproducible) layout. The optimal length is more and indication in the algorithm than a guarantee that all nodes will be at this distance. The result of the layout is really a combination of the incidence structure of the diagram, the initial topology (positions of the nodes) and the number of iterations.
RadDiagram does not offer any force-directed specific subtypes. The result of this layout depends on the values configured to the LayoutSettings’ Iterations and NodeDistance properties. You can find information about these properties in the Layout Basics article.