Molecular Design of Ionization-Induced Proton Switching Element Based on Fluorinated DNA Base Pair

2020

J. Phys. Chem. A

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Ammonia cluster cations are a chemical species that has recently attracted considerable research attention as an ion−molecule reaction species in the planetary atmosphere, surface reaction species in materials chemistry, and super-alkali species. Reactions of the radical cation of an ammonia cluster, [(NH 3 ) n ] + (n = 2−6), following the ionization of the parent neutral cluster, were investigated using direct ab initio molecular dynamics to elucidate the reactions of the ammonia cluster cation under astrochemical conditions. The calculations showed that two competing reaction channelsproton transfer (PT) channel and complex formation channeloperate after the ionization of neutral clusters. In the PT channel, a proton of NH 3 + was transferred to a neighboring ammonia molecule. The PT channel was found in all clusters (n = 2−6). Reaction via the PT channel became faster with increasing cluster size and saturated around n = 5− 6. In the complex formation channel, a face-to-face complex having a H 3 N−NH 3 + structure (with a N−N bond) was formed. This channel was found only in larger clusters (n = 5−6). Time scales of PT and complex formation channels were calculated to be 20− 30 and 40−50 fs, respectively. The reaction mechanism was discussed based on the results of theoretical calculations.

Section: Computational Detailsmentioning

confidence: 99%

Intramolecular Reactions in Ionized Ammonia Clusters: A Direct Ab Initio Molecular Dynamics Study

2020

J. Phys. Chem. A

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“…Additional calculations were carried out at the same level of theory for the lithium system. We previously investigated interactions between graphene and various molecules using DFT at the same level of theory [29][30][31][32][33]. A similar technique was used for the GR-Na-(H 2 ) n system in this study.…”

Section: Methodsmentioning

confidence: 99%

Hydrogen Storage Mechanism in Sodium-Based Graphene Nanoflakes: A Density Functional Theory Study

Iyama

et al. 2022

Hydrogen

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Carbon materials, such as graphene nanoflakes, carbon nanotubes, and fullerene, can be widely used to store hydrogen, and doping these materials with lithium (Li) generally increases their H2-storage densities. Unfortunately, Li is expensive; therefore, alternative metals are required to realize a hydrogen-based society. Sodium (Na) is an inexpensive element with chemical properties that are similar to those of lithium. In this study, we used density functional theory to systematically investigate how hydrogen molecules interact with Na-doped graphene nanoflakes. A graphene nanoflake (GR) was modeled by a large polycyclic aromatic hydrocarbon composed of 37 benzene rings, with GR-Na-(H2)n and GR-Na+-(H2)n (n = 0–12) clusters used as hydrogen storage systems. Data obtained for the Na system were compared with those of the Li system. The single-H2 GR-Li and GR-Na systems (n = 1) exhibited binding energies (per H2 molecule) of 3.83 and 2.72 kcal/mol, respectively, revealing that the Li system has a high hydrogen-storage ability. This relationship is reversed from n = 4 onwards; the Na systems exhibited larger or similar binding energies for n = 4–12 than the Li-systems. The present study strongly suggests that Na can be used as an alternative metal to Li in H2-storage applications. The H2-storage mechanism in the Na system is also discussed based on the calculated results.

“…A total of 30 trajectories were run in the thermal sampling. Details of sampling methods were described in our recent paper [42].…”

Section: Direct Aimd Calculations From Thermal Activation Regionmentioning

confidence: 99%

Ionization dynamics of the branched water cluster: A long-lived non-proton-transferred intermediate

Computational and Theoretical Chemistry

Takada

2016

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a b s t r a c tThe proton transfer (PT) reaction after water cluster ionization is known to be a very fast process occurring on the 10-30 fs time scale. In the present study, the ionization dynamics of the branched water tetramer (H 2 O) 4 were investigated by means of a direct ab initio molecular dynamics (AIMD) method to elucidate the time scale of PT in the water cluster cation. A long-lived non-proton-transferred intermediate was found to exist after the ionization of the branched-type water cluster. The lifetimes of the intermediate were calculated to be ca. 100-150 fs. PT occurred after the formation of the intermediate. The structure of the intermediate was composed of a symmetric cation core: H 2 O-H 2 O + -H 2 O. The broken symmetry of the structure led to PT from the intermediate. The reaction mechanism is discussed based on the theoretical results.