Hiroto Tachikawa

Direct molecular orbital-molecular dynamics (MO-MD) calculation was applied to diffusion processes of the Li atom on a model surface of amorphous carbon and compared with the diffusion mechanism of Li+ ion. A carbon sheet composed of C96H24 was used as the model surface. The total energy and energy gradient on the full dimensional potential energy surface of the LiC96H24 system were calculated at each time step in the trajectory calculation. The optimized structure, where the Li atom is located

The ionization dynamics of the water clusters (H2O)n (n = 3−6) have been investigated by means of the full-dimensional direct ab initio trajectory method. The static ab initio and DFT calculations were carried out at the HF/6-311G(d,p) and B3LYP/6-311G(d,p) levels, whereas the direct ab initio trajectory calculations were performed at the HF/6-31G(d) and 6-311G(d,p) levels of theory. The static ab initio and DFT calculations showed that the most stable structure is the cyclic form for all cases

Diffusion processes of the Li+ ion on a model surface of amorphous carbon (Li+C96H24 system) have been investigated by means of the direct molecular orbital (MO) dynamics method at the semiempirical AM1 level. The total energy and energy gradient on the full-dimensional AM1 potential energy surface were calculated at each time step in the dynamics calculation. The optimized structure, where Li+ is located in the center of the cluster, was used as the initial structure at time zero. The dynamics

Electronic states of normal graphene, the defective graphene (one carbon atom is removed from the normal graphene), the defective graphene anion (defective graphene plus an excess electron), and the defective graphene cation (defective graphene plus one hole) have been investigated by means of density functional theory (DFT) and direct molecular orbital−molecular dynamics (MO-MD) methods in order to elucidate the effect of vacancy defect on the electronic states of graphene. The HOMO and LUMO of

A direct molecular orbital−molecular dynamics (MO-MD) method has been applied to diffusion processes of the Li+ ion on a fluorinated graphene surface. A graphene sheet composed of C96F24 (denoted by F-graphene) was used as a model of the fluorinated graphene surface. The total energy and energy gradient on the full dimensional potential energy surface of the Li+C96F24 system were calculated at each time step in the trajectory calculation. The calculations were carried out at the AM1 level. Simul

Ionization processes of benzene−water cluster Bz(H2O)n (n = 1 and 2) have been studied by means of direct ab initio dynamics calculations. The ab initio calculations for the BzH2O 1:1 neutral complex show that in the minimum energy structure the water hydrogens point toward the center of mass of the benzene ring (the dipole orientation form). The potential energy curve calculated as a function of the benzene−H2O center of mass distance (Rcm) indicates that the H2O molecule is weakly bound to the

Carbon materials, such as graphene nanoflakes, carbon nanotubes, and fullerenes, can be used for hydrogen storage. Alkali doping of these materials generally increases their H2-storage density. In this study, the interaction of hydrogen molecules with Li-doped graphene nanoflakes was systematically investigated using density functional theory (DFT). A large polycyclic aromatic hydrocarbon composed of 37 benzene rings (referred to as GR) was used as a model of a graphene nanoflake, and GR–Li–(H2)

A microsolvated SN2 reaction of F-(H2O) with CH3Cl has been investigated by means of direct ab initio dynamics calculations in order to elucidate a detailed reaction mechanism. A full dimensional ab initio potential energy surface including all degrees of freedom was used in the dynamics calculations. Total energies and gradients were calculated at each time step. The vibrational phase of CH3Cl was generated classically so as to take a temperature of 10 K. The dynamics calculations showed that t

Ionization processes of a water dimer have been investigated by means of full dimensional direct ab-initio trajectory method. The structure of (H2O)2 before the ionization was simulated at 10 K up to 2 ps by means of a direct ab-initio molecular dynamics (MD) method. Sixty geometrical configurations were selected from the MD calculation, and then the dynamics of (H2O)2+ were calculated by means of a direct ab-initio trajectory method under a constant energy condition. The trajectories on two ele

Ionization dynamics of a water dimer have been investigated by means of a direct ab initio molecular dynamics (MD) method. Two electronic state potential energy surfaces of (H(2)O)(2)(+) (ground and first excited states, (2)A'' and (2)A') were examined as cationic states of (H(2)O)(2)(+). Three intermediate complexes were found as product channels. One is a proton transfer channel where a proton of H(2)O(+) is transferred into the H(2)O and then a complex composed of H(3)O(+)(OH) was formed. The

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectronic-to-Vibrational and -Rotational Energy Transfer in the O(1D) + N2 Quenching Reaction: Ab Initio MO and Surface-Hopping Trajectory StudiesHiroto Tachikawa, Takayuki Hamabayashi, and Hiroshi YoshidaCite this: J. Phys. Chem. 1995, 99, 45, 16630–16635Publication Date (Print):November 1, 1995Publication History Published online1 May 2002Published inissue 1 November 1995https://pubs.acs.org/doi/10.1021/j100045a023https://doi.org/10.1021/j100045a023

Finite temperature effects on the hyperfine coupling constant (HFCC) of a weakly bonded molecular complex have been investigated by a direct ab initio dynamics method. The complex composed of methyl radical and HF molecule, CH3···HF, was chosen as a model of the weakly bonded molecular complex. This complex was recently found as an intermediate in a hydrogen abstraction reaction F + CH4 by both electron spin resonance (ESR) and infrared (IR) spectroscopies at low temperature. The geometry optimi

Reaction dynamics for a microsolvated SN2 reaction OH-(H2O)+CH3Cl have been investigated by means of the direct ab initio molecular dynamics method. The relative center-of-mass collision energies were chosen as 10, 15, and 25 kcal/mol. Three reaction channels were found as products. These are (1) a channel leading to complete dissociation (the products are CH3OH+Cl- +H2O: denoted by channel I), (2) a solvation channel (the products are Cl-(H2O)+CH3OH: channel II), and (3) a complex formation cha

Electron attachment dynamics of excess electron in water cluster (H2O)n (n = 2 and 3) have been investigated by means of full-dimensional direct ab initio molecular dynamics (MD) method at the MP26-311++G(d,p) level. It was found that the hydrogen bond breaking due to the excess electron is an important process in the first stage of electron capture in water trimer. Time scale of electron localization and hydrogen bond breaking were determined by the direct ab initio MD simulation. The initial p