Allows for creation of arbitrary scalar potentials to represent forces acting in the system.
The input-field can take any analytical expressions described in the Expressions-page. Within the expression you have access to the variables x, a, and b, where x is the spatial dimension input and a/b are the scalar inputs to the node.
Similar to other expression-nodes, this node sometimes shows errors such as "unable to match input to struct...". This error means the input in the textfield is invalid. See the Expressions-page for a reference of valid expressions.