Collisional Reactions of Energetic Methane Molecules with Single-Walled Carbon Nanotubes

We study the collisions of energetic methane molecules with single-walled carbon nanotubes in the incident energyrange from 5 to 100 eV using classical molecular dynamics simulations combined with ab initio calculations. Themethane molecules can be decomposed into different hydrocarbon radicals, e.g. CHn (n = 1-3), in the collisionsdepending on the incident energy. Chemical functionalization of the single-walled carbon nanotubes resulting fromthe chemical adsorption of these hydrocarbon radicals on the outside wall of single-walled carbon nanotubes canbe achieved simultaneously. Some stable adsorption configurations of hydrocarbon-functionalized single-walledcarbon nanotubes are also presented based on ab initio calculations.     

Influence of High Atomic Hydrogenation on the Electronic Structure of Zigzag Carbon Nanotubes： A First-Principles Study

Using density functional theory, we study high hydrogenated zigzag single-walled carbon nanotubes from （7,0） to （11,0）. Two structure transitions are classified： type A is a metallic transition and type B is a ＂semiconductive transition＂ according to the energy band structure. The charge density transforms only at the C-C bonds without hydrogenated sites. The sp^3 hybridization is mainly enhanced for all the C-C bonds in the vertical axial direction for type-A configurations, and the sp^3 hybridization mainly increases for all C-C bonds along the axial direction for the type-B case.     

高压下TiN的结构转变、弹性和热力学性质的第一性原理计算

利用基于密度泛函的第一性原理,计算了高压下TiN的结构转变、弹性和热力学性质。计算结果表明：在压力作用下,TiN经历了从NaCl型结构到CsCl型结构的转变,转变压力为348 GPa;TiN的弹性系数随着压力的增加呈线性增加规律。此外,还给出了德拜温度和热容量这两个重要热力学量与温度和（或）压力的依赖关系。     

Accurate Analytic Potential Energy Function and Spectroscopic Study for G1 ∏g State of Dimer 7Li2

The reasonable dissociation limit for the G1∏g state of dimer 7Li2 is determined. The equilibrium internuclear distance, dissociation energy, harmonic frequency, vibrational zero energy, and adiabatic excitation energy are calculated using a symmetry-adapted-cluster configuration-interaction method in complete active space in Gaussian03 program package at such numerous basis sets as 6-311 G, 6-311 G(2df, 2pd), 6-311 G(2df, p), cc-PVTZ, 6-311 G(3df, 3pd), CEP-121G, 6-311 G(2df, pd), 6-311 G(d,p),6-311G(3df,3pd), D95(3df,3pd), 6-311 G(3df, 2p),6-311 G(2df), 6-311 G(df, pd) D95V , and DGDZVP. The complete potential energy curves are obtained at these sets over a wide internuclear distance range and have least squares fitted to Murrell-Sorbie function. The conclusion shows that the basis set 6-311 G(2df, p) is a most suitable one for the G1∏g state. At this basis set, the calculated spectroscopic constants Te, De, Eo, Re, ωe, ωeXe, αe, and Be are of 3.9523 eV, 0.813 06 eV, 113.56 cm-1, 0.320 15 nm,227.96 cm-1, 1.6928 cm-1, 0.004 436 cm-1, and 0.4689 cm-1, respectively, which are in good agreement with measurements whenever available. The total 50 vibrational levels and corresponding inertial rotation constants are for the first time calculated and compared with available RKR data. And good agreement with measurements is obtained.     

Accurate Analytic Potential Energy Function and Spectroscopic Study for G^1Ⅱg State of Dimer ^7Li2

The reasonable dissociation limit for the G^1Ⅱg, state of dimer ^7Li2 is determined. The equilibrium internuclear distance, dissociation energy, harmonic frequency, vibrational zero energy, and adiabatic excitation energy are calculated using a symmetry-adapted-cluster configuration-interactlon method in complete active space in Gaussian03 program package at such numerous basis sets as 6-311 ＋＋G, 6-311 ＋＋G（2df,2pd）, 6-311 ＋＋G（2df, p）, cc-PVTZ, 6- 311＋＋G（3df,3pd）, CEP-121G, 6-311＋＋G（2df, pd）, 6-311＋＋G（d,p）,6-311G（3df,3pd）, D95（3df,3pd）, 6-311＋＋G（3df,2p）, 6-311＋＋G（2df）, 6-311＋＋G（df, pd） D95V＋＋, and DGDZVP. The complete potential energy curves are obtained at these sets over a wide internuclear distance range and have least squares fitted to Murrell-Sorbie function. The conclnsion shows that the basis set 6-311＋＋G（2df, p） is a most suitable one for the G^1Ⅱg state. At this basis set, the calculated spectroscopic constants Te, De, Eo, Re, ωe, ωeXe, ae, and Be are of 3.9523 eV, 0.813 06 eV, 113.56 cm^-1, 0.320 15 nm, 227.96 cm^-1, 1.6928 cm^-1, 0.004 436 cm^-1, and 0.4689 cm^-1, respectively, which are in good agreement with measurements whenever available. The total 50 vibrational levels and corresponding inertial rotation constants are for the first time calculated and compared with available RKR data. And good agreement with measurements is obtained.     

Complexes between H2 and neutral oxyacid beryllium derivatives. The role of angular strain

ABSTRACT

The complexes between 14 different Be-salts of oxyacids from groups 13 to 16 with one and two molecules of H₂ have been investigated by means of the MP2/aug-cc-pVTZ ab initio molecular orbital theory method, which was found to be reliable for the treatment of these weakly bound species. The main conclusion is that these Be-salts yield rather stable complexes with dihydrogen, with binding energies one order of magnitude larger than other typical H₂ complexes reported in the literature. This strong binding is shown to be due to an enhancement of the electron-deficient nature of Be when attached to an oxyacid moiety, which depends more on the type of coordination of the central atom of the oxyacid moiety. The formation of these complexes is followed by a significant lengthening of the H₂ internuclear distance and a concomitant red-shift of the H–H stretching frequency, which becomes a good indicator of the strength of the interaction. The charge shifting from the bonding region of the H₂ molecule to the interboundary Be···H₂ region is the physical phenomenon behind the stability of these complexes. Accordingly, the most important contributor to this stability is the inductive term, followed by the electrostatic interactions. The ability of Be to bind H₂ is enhanced by the angular arrangement of the O–Be–O electron-acceptor group.     

Simple(r) algebraic equation for transition moments of fundamental transitions in vibrational second-order perturbation theory

Rayleigh–Schrödinger perturbation theory is applied in second order to obtain an expression for the transition moment of vibrational fundamentals. The reported equation is considerably simpler than previous ones. Applications for H₂O and HFCO are reported using force fields and dipole functions calculated at the CCSD(T) level of theory with different basis sets.