Herramienta SMT que admite punto fijo

By fixpoint, I presume you mean solving for Horn clause queries. There are many tools that solve problems of a similar nature, but perhaps not with precisely the same format. Philippe Suter's Leon tool uses different algorithms and can solve many correctness queries over recursive programs. Andrey Rybalchenko's ARMC tool solves Horn formulas with linear real arithmetic as well. It can also establish termination conditions. CLP systems with tabling should also be amenable to solving queries in a format that is similar to Z3's (both use Horn formulas as their input format). There are also many symbolic model checking solvers that could be used depending on your context.