Photofragmentation of Tetranitromethane: Spin-Unrestricted Time-Dependent Excited-State Molecular Dynamics

Yulun Han; Bakhtiyor Rasulev; Dmitri S Kilin

doi:10.1021/acs.jpclett.7b01330

Photofragmentation of Tetranitromethane: Spin-Unrestricted Time-Dependent Excited-State Molecular Dynamics

J Phys Chem Lett. 2017 Jul 20;8(14):3185-3192. doi: 10.1021/acs.jpclett.7b01330. Epub 2017 Jun 29.

Authors

Yulun Han^{1

2}, Bakhtiyor Rasulev³, Dmitri S Kilin^{1

2}

Affiliations

¹ Department of Chemistry, University of South Dakota , Vermillion, South Dakota 57069, United States.
² Department of Chemistry and Biochemistry, North Dakota State University , Fargo, North Dakota 58108, United States.
³ Department of Coatings and Polymeric Materials, North Dakota State University , Fargo, North Dakota 58102, United States.

PMID: 28618779
DOI: 10.1021/acs.jpclett.7b01330

Abstract

In this study, the photofragmentation dynamics of tetranitromethane (TNM) is explored by a spin-unrestricted time-dependent excited-state molecular dynamics (u-TDESMD) algorithm based on Rabi oscillations and principles similar to trajectory surface hopping, with a midintensity field approximation. The leading order process is represented by the molecule undergoing cyclic excitations and de-excitations. During excitation cycles, the nuclear kinetic energy is accumulated to overcome the dissociation barriers in the reactant and a sequence of intermediates. The dissociation pathway includes the ejection of NO₂ groups followed by the formation of NO and CO. The simulated mass spectra at the ab initio level, based on the bond length in possible fragments, are extracted from simulation trajectories. The recently developed methodology has the potential to model and monitor photoreactions with open-shell intermediates and radicals.