title: Role of Quantum Vibrations on the Structural, Electronic, and Optical Properties of 9-Methylguanine.
abstract: In this work, we report theoretical predictions of the UV-absorption spectra of 9-methylguanine using time dependent density functional theory (TDDFT). Molecular dynamics simulations of the hydrated DNA base are peformed using an empirical force field, Born-Oppenheimer ab initio molecular dynamics (AIMD), and finally path-integral AIMD to understand the role of the underlying electronic potential, solvation, and nuclear quantum vibrations on the absorption spectra. It is shown that the conformational distributions, including hydrogen bonding interactions, are perturbed by the inclusion of nuclear quantum effects, leading to significant changes in the total charge and dipole fluctuations of the DNA base. The calculated absorption spectra using the different sampling protocols shows that the inclusion of nuclear quantum effects causes a significant broadening and red shift of the spectra bringing it into closer agreement with experiments.
authors.affiliation: School of Natural Sciences and Mathematics, Indiana University East , Richmond, Indiana 47374, United States.
authors.forename: Yu Kay
authors.initials: YK
authors.lastname: Law
authors.affiliation: Condensed Matter Physics Section, The Abdus Salaam International Center for Theoretical Physics , Strada Costiera 11, Trieste 34151, Italy.
authors.forename: Ali A
authors.initials: AA
authors.lastname: Hassanali
mesh_terms: D003198:Computer Simulation; D004581:Electronics; D006147:Guanine / Q000031:analogs & derivatives* / Q000737:chemistry; D008968:Molecular Conformation; D055095:Optics and Photonics; D011789:Quantum Theory; D014732:Vibration
chemical_list: C116701:9-methylguanine; D006147:Guanine