By using first-principles simulations based on time-dependent density functional theory,the chemical reaction of an HCl molecule encapsulated in C60induced by femtosecond laser pulses is observed.The H atom starts to leave the Cl atom and is reflected by the C60wall.The coherent nuclear dynamic behaviors of bond breakage and recombination of the HCl molecule occurring in both polarized parallel and perpendicular to the H–Cl bond axis are investigated.The radial oscillation is also found in the two polarization directions of the laser pulse.The relaxation time of the H–Cl bond lengths in transverse polarization is slow in comparison with that in longitudinal polarization.Those results are important for studying the dynamics of the chemical bond at an atomic level.
We investigate the adsorptions of Ar on Al （111） and Ir （111） surfaces at the four high symmetry sites, i.e., top, bridge, fcc- and hcp-hollow sites at the coverage of 0.25 monolayer （ML） using the density functional theory within the generalized gradient approximation of Perdew, Burke and Ernzerhof functions. The geometric structures, the binding energies, the electronic properties of argon atoms adsorbed on Al （111） and Ir （111） surfaces, the difference in electron density between on the Al （111） surface and on the Ir （111） surface and the total density of states are calculated. Our studies indicate that the most stable adsorption site of Ar on the Al （111） surface is found to be the fcc-hollow site for the （2 x 2） structure. The corresponding binding energy of an argon atom at this site is 0.538 eV/Ar atom at a coverage of 0.25 ML. For the Ar adsorption on Ir （111） surface at the same coverage, the most favourable site is the hcp-hollow site, with a corresponding binding energy of 0.493 eV. The total density of states （TDOS） is analysed for Ar adsorption on Al （111） surface and it is concluded that the adsorption behaviour is dominated by the interaction between 3s, 3p orbits of Ar atom and the 3p orbit of the base Al metal and the formation of sp hybrid orbital. For Ar adsorption on Ir （111） surface, the conclusion is that the main interaction in the process of Ar adsorption on Ir （111） surface comes from the 3s and 3p orbits of argon atom and 5d orbit of Ir atom.
A novel type of Ti decorating benzene grafted tetrahydrido-silsequioxane struc-tures was designed and investigated using density functional theory（DFT）.The hydrogen adsorption properties of this new material were investigated at the same level of theory.The results reveal that up to four hydrogen molecules（with the restrict of 18 electrons rule） can be adsorbed on each Ti atom of（TiC6H5）m-H4-mSi4O6（m = 1-4） molecular systems with the average binding energies of 0.691,0.692,0.693 and 0.695 eV for m = 1-4,respectively.The variations of HOMO- LUMO energy gaps verify that the host structures with four H2 molecules adsorbed own the best kinetics stability.The interaction mechanism of H2 molecules with the host materials mainly attributes to the well-known ＂kubas interactions＂.All the results indicate that the complex structures designed here may be used as hydrogen storage materials at ambient conditions.
In the present paper we give a detailed report on the results of our first-principles investigations of Ar adsorptions at the four high symmetry sites on M （111） （M =Pd, Pt, Cu, and Rh） surfaces. Our studies indicate that the most stable adsorption sites of Ar on Pd （111） and Pt （111） surfaces are found to be the fcc-hollow sites. However, for Ar adsorptions on Cu （111） and Rh （111） surfaces, the most favorable site is the on-top site. The density of states （DOS） is analyzed for Ar adsorption on M （111） surfaces, and it is concluded that the adsorption behavior is dominated by the interaction between 3s, 3p orbits of Ar atoms and the d orbit of the base metal atoms.
Our calculations demonstrate that the concentration of neutral oxygen vacancies can affect the geometrical structrue,electronic structure, and optical properties of α-quartz. Moreover, the distribution of the neutral oxygen divacancy can also exert some influence on the properties of α-quartz. The dissimilarity and similarities are presented in the corresponding density of state（DOS） and absorption spectrum. In addition, when a higher defect concentration is involved in α-quartz,the influence of E1 center on the geometry of α-quartz becomes more significant. However, the introduction of an E1 center barely results in any improvement compared with the influence produced by the corresponding neutral defect.
A new hydrogen storage route of 3D nanoporous sodium borohydride (NPSB) generated by removing special atoms is proposed in this work. Three different size pores of NPSB-1 (7), NPSB-2 (10) and NPSB-3 (14) are presented, and the hydrogen storage capacities of these NPSBs are simulated by employing a grand canonical Monte Carlo (GCMC) procedure for a temperature range of 77-298 K and a pressure range of 0.1-100 bar. The effects of pore diameter, temperature and pressure on the hydrogen adsorption have been examined. The results show that the adsorption of hydrogen decreases and increases with increasing temperature and hydrogen pressure, respectively. It also reflects that the hydrogen adsorption capacities at higher pressures are dependent on pore diameter, while independent of pore diameter at lower pressures.
The binding energies, geometric structures and electronic properties of molybde- num trioxide （MOO3） molecule encapsulated inside （8, 0）, （9, 0）, （10, 0） and （14, 0） single-walled carbon nanotubes （SWNTs） have been investigated using density functional theory （DFT） method. Due to curvature effect, the calculated binding energy values are different, the variation of which indicated that the stability of MoO3/SWNT systems increases with increasing the radius of SWNTs. At the same time, owing to the presence of MoO3 molecule, the band gap of MoO3/SWNTs systems decreases. The analysis of density of states （DOS） reveals hybridization between C-2p and Mo-4d and between C-2p and O-2p orbitals near the Fermi level, which results in electron transfer from SWNTs to MoO3 molecule. The present computations suggest that electronic properties of SWNTs can be modified by doping MoO3 molecule.
Activated carbon aerogels（ACAs） derived from sol-gel polycondensation of resorcinol （R） and formaldehyde （F） were pyrolyzed under Ar flow and activated in CO2 atmosphere. The morphology of ACAs was characterized by scanning electron microscopy （SEM） and the structural properties were determined by N2 adsorption at 77 K. The results show that ACAs have a typical three-dimensional nanonetwork structure composing of cross-linking of carbon nanoparticles. The specific surface area and the total pore volume remarkably increase with increasing activation time while the previous porous structure still remains. The specific capacitance of the 950-10-ACA electrode can reach up to 212.3 F/g in 6 mol/L KOH electrolyte. The results of constant-current charge-discharge testing indicate that the ACAs electrodes present fast charge- discharge rate and long cycle life （about 98% capacitance retained after 3000 charge-discharge cycles at 1.25 mA/cm2）. Lower internal resistances can be achieved for 950-10-ACA electrode in KOH electrolyte. Our investigations are very important to improve the wettability and electrochemical performance of electrode for supercapacitors.
We studied the co-adsorption of hydrogen molecule and ions （Li, K, Mg, Ca） inside the single-walled carbon nanotubes （SWNTs） by using density-functional theory （DFT）. The band structures （BS）, density of states （DOS）, charge transfer and difference charge density are presented. We discussed the interaction between the ions （Li, K, Mg, Ca） and H2 Meanwhile, the binding energy indicates that ionization can increase the adsorption energy of H2 in CNT.
