State-Resolved Vibrational Spectra of Fluxional Protonated Water Clusters via Tensor Network States

University Of California - Merced, Merced CA

Investigators

Abstract

With support from the Chemical Theory, Models and Computational Methods (CTMC) program in the Division of Chemistry (CHE), Henrik R. Larsson of the University of California, Merced is developing new theoretical methods that will be applied to unravel quantum effects in protonated water clusters. These clusters are key to understanding the fundamental properties of water, such as its acidity, which depend on many complex quantum interactions. Henrik R. Larsson and his research group will be developing methods that are designed to enable an efficient and accurate simulation of protonated water clusters with nearly an order of magnitude increase in complexity relative to previous work. The methods developed in this research are expected to be generally applicable to a broad class of quantum systems in a wide range of fields including energy sciences, and astro- and photochemistry. Dr. Larsson plans to co-organize an interdisciplinary workshop within the Quantum Dynamics Network about developing new methods for simulating quantum systems to bring scientific communities from different fields together. Plans are in place for Dr. Larsson to engage early career scientists in the exciting field of molecular quantum dynamics by lecturing at a summer school. The principal investigator also aims to involve economically disadvantaged high school students, through ACS Project Seed, and first generation undergraduate students in research activities that are directly linked to this project. Dr. Henrik R. Larsson and his research group at the University of California, Merced will develop methods for full-dimensional vibrational quantum dynamics simulations. The methods they will develop are based on tensor network states, leveraging the power of the density matrix renormalization group (DMRG) and of the multilayer multi-configurational time-dependent Hartree (ML-MCTDH) method. They will apply these new methods to understanding the effects of finite temperature, isotope substitution and microsolvation on the proton transfer motion and the infrared spectrum of protonated water clusters. They will optimize and analyze highly excited wavefunctions that lead to poorly understood experimental spectra. Differences and similarities between the clusters will be analyzed by means of explicit wavefunction comparisons and by reduced-dimensional simulations. The methods developed in this program are expected to be broadly applicable beyond the study of vibrational fluxional states and, for example, will likely be useful for simulating nonadiabatic dynamics and for computing excited electronic states. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.