Adiabatic Landau-Zener-St\"uckelberg transition with or without   dissipation in low spin molecular system V15
  The spin one half molecular system V15 shows no barrier against spin reversal. This makes possible direct phonon activation between the two levels. By tuning the field sweeping rate and the thermal coupling between sample and thermal reservoir we have control over the phonon-bottleneck phenomena previously reported in this system. We demonstrate adiabatic motion of molecule spins in time dependent magnetic fields and with different thermal coupling to the cryostat bath. We also discuss the origin of the zero-field tunneling splitting for a half-integer spin. 
I. Chiorescu, W. Wernsdorfer, A. Mueller, S. Miyashita, B. Barbara