Semiclassical Spectroscopy of Water Clusters Using High-Level Ab Initio Potentials

I will start introducing state-of-art techniques in semiclassical dynamics that allow one to undertake vibrational spectroscopy simulations involving many degrees of freedom and complex molecules. An important class of such systems is represented by water clusters, which also serve as prototypical examples of water (micro-)solvation. I will present some calculations on small water clusters (from the dimer through the decamer) to benchmark my semiclassical approach against MultiMode VCI estimates obtained by means of the ab initio WHBB potential energy surface, which I also adopted for the semiclassical simulations. Then, I will show results of a semiclassical study aimed at determining the minimum water cluster structure able to reproduce the spectroscopic features of liquid water including the libration-bending combination band. For this study, involving a larger number of degrees of freedom, I employed the accurate and faster-to-evaluate MB-Pol potential energy surface. Finally, some remarks about possible developments on water cluster calculations will be briefly illustrated.