  We investigate the surface adsorption transition of interacting self-avoiding
square lattice trails onto a straight boundary line. The character of this
adsorption transition depends on the strength of the bulk interaction, which
induces a collapse transition of the trails from a swollen to a collapsed
phase, separated by a critical state. If the trail is in the critical state,
the universality class of the adsorption transition changes; this is known as
the special adsorption point. Using flatPERM, a stochastic growth Monte Carlo
algorithm, we simulate the adsorption of self-avoiding interacting trails on
the square lattice using three different boundary scenarios which differ with
respect to the orientation of the boundary and the type of surface interaction.
We confirm the expected phase diagram, showing swollen, collapsed, and adsorbed
phases in all three scenarios, and confirm universality of the normal
adsorption transition at low values of the bulk interaction strength.
Intriguingly, we cannot confirm universality of the special adsorption
transition. We find different values for the exponents; the most likely
explanation is that this is due to the presence of strong corrections to
scaling at this point.
