Zlatko Bacic's Research Interests
Professor Bacic's group has been developing computational methods for a rigorous treatment of the quantum dynamics and spectroscopy of a wide range of most challenging floppy polyatomic molecules and weakly bound molecular clusters, intractable for conventional bound-state approaches. These novel methods allow accurate prediction of the vibration-rotation levels, tunneling splittings, and spectral shifts of small hydrogen-bonded clusters such as (HF)2, (HCl)2, (H2O)3, and (H2O)4, as well as of molecule-doped van der Waals heteroclusters, e.g., ArnHF and ArnOH. His group's research activity has been recently extended to several problems of significantly higher dimensionality and complexity. One of them is the vibration- tunneling dynamics of hydrogen-bonded dimers, (HF)2 and (HCl)2, in liquid helium droplets, whose description is sought by means of full-dimensional diffusion quantum Monte Carlo (DQMC) calculations.
The DQMC treatment of H2O and NH3 dimers in He droplets will be undertaken in the next stage of the investigation. The objective of another new project is the eigenstate-resolved description of hydrogen-bonded dimers having a low barrier to proton transfer, like H5O2+ and H3O2-, in which the anharmonic proton-transfer motions are coupled to other large-amplitude cluster vibrations. His group is also developing high-dimensional quantum methods for calculating excited vibrational levels of hydrogen atoms adsorbed on metal clusters, including the vibrations of metal atoms, and for coupled anharmonic vibrations of small molecules, e.g., CO and H2O, adsorbed on corrugated metal surfaces.
|FIGURE: Contour plot of the 3D O···H···O subspace of the potential energy surface of the protonated water dimer, H5O2+, in the hyperspherical coordinates ρ, θ, and χ. The cut in χ (asymmetric O···H···O stretch) and ρ (symmetric O···H···O stretch) is shown for the O···H···O bend coordinate θ=175°; χ is in radians and ρ in bohrs. The spacing between the contours is 1000 cm-1.|