title: Time-Domain Simulations of Transient Species in Experimentally Relevant Environments.
abstract: Simulating the spectroscopic properties of short-lived thermal and photochemical reaction intermediates and products is a challenging task, as these species often feature atypical molecular and electronic structures. The complex environments in which such species typically reside in practice add further complexity to the problem. Herein, we tackle this problem in silico using ab initio molecular dynamics (AIMD) simulations, employing iso-CHBr3, namely H(Br)C-Br-Br, as a prototypical system. This species was chosen because it features both a nonconventional C-Br-Br bonding pattern, as well as a strong dependence of its spectral features on the local environment in which it resides, as illustrated in recent experimental reports. We simulate the UV-vis and IR spectra of iso-CHBr3 in the gas phase, as well as in a Ne cluster (64 atoms) and in a methylcyclohexane cage (14 solvent molecules) representative of the previously characterized matrix isolated and solvated iso-CHBr3 species. We exclusively perform fully quantum mechanical static and dynamic simulations. By comparing our condensed phase simulations to their experimental analogues, we stress the importance of (i) conformational sampling, even at cryogenic temperatures, and (ii) using a fully quantum mechanical description of both solute and bath to properly account for the experimental observables.
authors.affiliation: Physical Sciences Division, Pacific Northwest National Laboratory , P. O. Box 999, Richland, Washington 99352, United States.
authors.forename: Tyler W
authors.initials: TW
authors.lastname: Ueltschi
authors.affiliation: Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory , Richland, Washington 99352, United States.
authors.forename: Sean A
authors.initials: SA
authors.lastname: Fischer
authors.affiliation: Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory , Richland, Washington 99352, United States.
authors.forename: Edoardo
authors.initials: E
authors.lastname: Aprà
authors.affiliation: Department of Chemistry and Center for Photochemical Sciences, Bowling Green State University , Bowling Green, Ohio 43403, United States.
authors.forename: Alexander N
authors.initials: AN
authors.lastname: Tarnovsky
authors.affiliation: Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory , Richland, Washington 99352, United States.
authors.forename: Niranjan
authors.initials: N
authors.lastname: Govind
authors.affiliation: Physical Sciences Division, Pacific Northwest National Laboratory , P. O. Box 999, Richland, Washington 99352, United States.
authors.forename: Patrick Z
authors.initials: PZ
authors.lastname: El-Khoury
authors.affiliation: Physical Sciences Division, Pacific Northwest National Laboratory , P. O. Box 999, Richland, Washington 99352, United States.
authors.forename: Wayne P
authors.initials: WP
authors.lastname: Hess