Time-dependent propagator with point interaction

We compute the time-dependent Schrodinger propagator with a point interaction in dimension n less-than-or-equal-to 3 including the new cases of n = 2 and the most general interaction supported by a point for n = 1. We also give the small-time asymptotics for n less-than-or-equal-to 3. The case n = 2 has the peculiarity of involving logarithmic terms in the expansion