A surge of progress in both laser spectroscopy experiments and theoret
ical dynamics methods has facilitated new, highly detailed studies of
water clusters. The geometrical structures and hydrogen-bond tunneling
pathways of the water trimer, tetramer, pentamer, and hexamer systems
have recently been characterized with global analysis of potential su
rfaces, diffusion Monte Carte calculations, and far-infrared laser vib
ration-rotation tunneling spectroscopy. Results from these and other s
tudies are yielding important insights into the cooperativity effects
in hydrogen bonding, aqueous solvation, and hydrogen-bond network rear
rangement dynamics, which promise to enhance our understanding of soli
d and liquid water behavior.