Uniform semiclassical approximation in quantum statistical mechanics
  We present a simple method to deal with caustics in the semiclassical approximation to the partition function of a one-dimensional quantum system. The procedure, which makes use of complex trajectories, is applied to the quartic double-well potential. 
C. A. A. de Carvalho, R. M. Cavalcanti, E. S. Fraga, and S. E. Joras