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Geometries, relative energies, and stabilities of endo- and exohedral complexes, X@Si20H20 and XSi20H20, (X = H+, H, N, P, C?, and Si?) are calculated at B3LYP/6-31G* level. The energy minimum structure of Si20H21 + shows that the proton cannot be positioned in the Si20H20 centre, but prefers attach to Si20H20 exohedrally with C2v symmetry. Most investigated Ih endohedral complexes X@Si20H20 (X = H, N, P, C?, and Si?) are local minima, except for 2N@Si20H20, which is a high-order saddle point. Inclusions energies of the endohedral complexes are calculated, and it reveals that energy penalties caused by encapsulation are rather small. Exohedral complexes XSi20H20 (X = H, N, P, C?, and Si?) have C2v or Cs local minima, and most of them are more stable than their endohedral isomers with the exception of C2v 4PSi20H20 and 4Si?Si20H20. 相似文献
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An atom or molecule far from a surface experiences an interaction V ~ ?C3z?3, where z is the distance to the surface. We compute the coefficient C3 for He, H, and H2 interacting with a graphite surface. The calculation utilizes measured frequency dependent values of the polarizabilities and dielectric function. Comparison is made with C3 values deduced from surface scattering and adsorption experiments. 相似文献
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N. A. Golovina A. P. Polishchuk G. A. Puchkovskaya 《Journal of Applied Spectroscopy》1990,52(4):416-423
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 52, No. 4, pp. 627–635, April, 1990. 相似文献
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Some one-electron molecular properties are calculated for BH3, BH4 -, B2H6, B4H4, CH4, C2H2, C2H4, C2H6, and C3H4. The wave functions used are constructed from minimal basis sets of STO's and FSGO's. The results obtained from the latter wave functions show that the good agreement with the STO values of the molecular energy is not always maintained with one-electron properties. 相似文献
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Maciej Psarski Jacek Marczak Grzegorz Celichowski Grzegorz B. Sobieraj Konrad Gumowski Feng Zhou Weimin Liu 《Central European Journal of Physics》2012,10(5):1197-1201
Nature inspires the design of synthetic materials with superhydrophobic properties, which can be used for applications ranging from self-cleaning surfaces to microfluidic devices. Their water repellent properties are due to hierarchical (micrometer- and nanometre-scale) surface morphological structures, either made of hydrophobic substances or hydrophobized by appropriate surface treatment. In this work, the efficiency of two surface treatment procedures, with a hydrophobic fluoropolymer, synthesized and deposited from 1H,1H,2H,2H-perfluorooctyltrichlorosilane (PFOTS) is investigated. The procedures involved reactions from the gas and liquid phases of the PFOTS/hexane solutions. The hierarchical structure is created in an epoxy nanocomposite surface, by filling the resin with alumina nanoparticles and micron-sized glass beads and subsequent sandblasting with corundum microparticles. The chemical structure of the deposited fluoropolymer was examined using XPS spectroscopy. The topography of the modified surfaces was characterized using scanning electron microscopy (SEM), and atomic force microscopy (AFM). The hydrophobic properties of the modified surfaces were investigated by water contact and sliding angles measurements. The surfaces exhibited water contact angles of above 150° for both modification procedures, however only the gas phase modification provided the non-sticking behaviour of water droplets (sliding angle of 3°). The discrepancy is attributed to extra surface roughness provided by the latter procedure. 相似文献
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Comparative investigations of secondary ion emission, electron induced ion emission and flash filament signals from polycrystalline vanadium surfaces exposed to well-defined O2, H2, H2O and (O2 + H2) doses (<500 L) have been carried out. The vanadium target could be heated and bombarded by either electrons (300 eV) or ions (3 keV) under ultra high vacuum conditions (<10?10 Torr). The investigations were carried out with a computer controlled ultra high vacuum mass spectrometer. The experimental results establish exact reproducible spectra of well defined surface layers. They give detailed insight into the reactions between H2, O2 H2O and vanadium, and some interactions between these species. They further indicate the importance of bulk and surface diffusion as well as the influence of the probing ion and electron bombardment. A clear distinction between bulk oxygen, surface oxides, and adsorbed oxygen for the vanadium-oxygen interaction at room temperature could be established. For the interaction of hydrogen with clean and oxygen covered vanadium surfaces the formation of adsorbed hydrogen, bulk solution of hydrogen, and the formation of OH groups and H2O could be demonstrated. A detection limit below 10?5 of one single monolayer for metal bonded hydrogen could be established. 相似文献
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Russian Physics Journal - Within the framework of the Minimal Supersymmetrtic Standard Model, we have investigated the decay channels of Higgs bosons into a photon and a gauge boson: H(h; A)... 相似文献
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《International Journal of Mass Spectrometry and Ion Physics》1978,26(2):205-213
The kinematics of the reaction H2O+(H2,H)H3O+ were studied in crossed-beam experiments in the low collision-energy range 0.1–2 eV (c.m.). The scattering diagrams, center-of-mass angular distributions, and product relative translational energy distributions obtained show that the reaction proceeds predominantly by the impulsive, stripping mechanism. The translational exoergicity vs. collision energy plot obeys the spectator-stripping prediction. 相似文献
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Sergey L. Khursan Mikhail Yu. Ovchinnikov 《Journal of Physical Organic Chemistry》2014,27(12):926-934
A scheme for the pKa estimation of organic acids in dimethylsulfoxide (DMSO) solution based on quantum chemical calculations is proposed. The procedure of pKa calculation requires several steps. The first is the calculation of the gas phase acidity of the compound. The G3MP2B3, G4MP2 as well as CBS‐QB3 composite methods made it possible to estimate values of gas phase acidities of an extensive set of structures with a high confidence level (standard deviations equal to 1.15, 1.13 and 1.29 kcal mol?1, respectively; the test set included 91 compounds). The second step is the computation of the solvation correction with the integral equation formalism version of polarizable continuum model (IEF‐PCM)–B3LYP/6‐311+G(d,p) approximation. Within the bounds of our approach, the medium properties were covered only by the PCM model, i.e. the proposed procedure neglects specific interactions between DMSO and the solute. It was determined that the approach to pKa estimation mentioned above is the most balanced in terms of accuracy, resource intensity and computation time cost. In the third step, the error of the pKa calculation was decreased by correlation allowances. Correlation allowances were determined for each acid class (62 С―Н, 55 N―Н, 24 O―Н and 5 S―Н acids) in the range of 50 units in terms of logarithmic scale using the test set including 146 compounds. Seven O―H acids showing the ability to form cyclic dimers were separated into a discrete group. The proposed methodology was applied to the estimation of pKa for trans‐ and cis‐dimethyl‐4,5‐dihydro‐3H‐pyrazol‐3,5‐dicarboxylates as well as for 5‐fluorouracil subject to competitive dissociation, the latter by N1―H or N3―H bonds. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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PdH、YH体系的结构与氢化反应的平衡压力 总被引:6,自引:4,他引:6
用相对论有效原子实势(RECP/SDD)和密度泛函(B3LYP)方法对PdH、YH体系的结构进行了优化,同时用Murrell-Sorbie函数导出PdH、YH分子的势能函数和光谱常数;得到PdH分子的基态为X2∑+,RPdH=0.154 1 nm,离解能De=2.511 eV,谐振频率ωe=2 019.458 9 cm-1;YH分子的基态为X1∑+,RYH=0.191 9 nm,离解能De=4.308 eV,谐振频率ωe=1 497.531 2 cm-1;并得到一键长为0.200 3nm,De=3.488 eV,ωe=1 309.318 2 cm-1的YH分子激发态.并根据以分子总能量中的振动能Ev代替固态能量,以电子和振动熵SEv代替固态熵的近似方法,计算了不同温度下Pd、Y与H2、D2、T2反应的一氢化物热力学函数△Hθ、△Gθ、△Sθ及氢化反应平衡压力,导出了与温度的依赖关系,结果表明:PdH(S)的生成焓为32.05kJ·md-1,与实验值37.30kJ·mol-1接近,YH(S)的生成焓为70.21 kJ·mol-1. 相似文献
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The zeroth-order theory of intermolecular forces is used to derive additivity relations for rotationally averaged molecular dipole properties and dispersion energy constants by assuming that a molecule is comprised of non-interacting atoms or molecules. Some of the additivity rules are new and others, for example the mixture rule for dipole oscillator strength distributions (DOSDs), Bragg's rule for stopping cross sections and Landolt's rule for molecular refractivities, are well known. The additivity rules are tested by using previously constructed DOSDs and reliable values for the dipole oscillator strength sums Sk , Lk and Ik , and dispersion energy constants C 6, for H, N, O, H2, N2, O2, NO, N2O, NH3 and H2O as models. It is found that additivity is generally unreliable for estimating molecular properties corresponding to k < -2. Generally for k ≥ -2 and for C 6, and if the hydrogen molecule is used to represent the hydrogen atom in the additivity rules, the additivity relations yield results that are reliable to within ?20 per cent and the estimates improve substantially as k increases. The effects of molecule formation on DOSDs is examined by comparing the various molecular DOSDs with the sum of the DOSDs for the atoms making up the molecules. Molecule formation results in a net decrease in the amount of dipole oscillator strength for low excitation energies and a compensating net increase for higher energies in a region extending from the absorption threshold to about 100 eV. This is shown to imply that estimates of the stopping average energy I 0, obtained by using bona fide atomic I 0 values, are lower bounds to the correct molecular I 0 results. 相似文献
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《Physics letters. A》2020,384(21):126533
Molybdenum trioxide (MoO3) with α-phase is a promising material for gas sensing because of its high sensitivity, fast response and thermodynamic stability. To probe the mechanism of superior gas detection ability of MoO3 monolayer, the adsorption and diffusion of H2, H2S, NH3, CO and H2O molecules on two-dimensional (2D) MoO3 layer are studied via density functional theory (DFT) calculations. Based on calculated adsorption energies, density of states, charge transfer, diffusion barriers and diffusion coefficient, MoO3 shows a superior sensitive and fast response to H2 and H2S than CO, NH3, H2O, which is consistent with experimental conclusions. Moreover, the response of MoO3 to H2S and H2 will be obviously enhanced at high gas concentration, and the incorporation of H2 and H2S results in an obvious increasing in DOS near Fermi level. Our analysis provides a conceptual foundation for future design of MoO3-based gas sensing materials. 相似文献
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Pablo A. Denis 《Molecular physics》2013,111(21-23):2557-2567
The HSOH, H2SO and H2OS isomers have been investigated employing the CCSD(T) methodology and the cc-pV(X + d)Z X = 3,4,5,6 basis sets. The anharmonic force fields have been calculated to predict the fundamental vibrational frequencies, rotational constants, vibration–rotation corrections, anharmonic corrections to zero-point energies, and structural parameters. In addition to this, a spectroscopic characterization of the deuterated isomers D2SO and D2OS was performed. At the CCSD(T)/CBS limit and including corrections for scalar relativistic, spin orbit and core-valence correlation effects, the estimated enthalpies of formation are ?28.1 ± 1, ?12.3 ± 1, and 10.1 ± 1 kcal/mol for HSOH, H2SO and H2OS, respectively. Finally, we discuss the problems faced during the extrapolation to the CBS limit of the properties investigated. 相似文献
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《Nuclear Physics A》1986,460(2):352-360
In the reaction 11B(88.0 MeV) + 9Be the energy spectra of the 14O, 15O and 16O nuclei have been measured to obtain some information about their partners in the exit channel — the neutron-rich hydrogen isotopes 4H, 5H and 6H. The unbound levels in the 4H and 6H systems have been observed at excitation energies of 3.5 ± 0.5 MeV (Γ ~1 MeV) and 2.6 ± 0.5 MeV (Γ = 1.5 ± 0.3 MeV), respectively. No evidence for the existence of any bound or unbound state in 5H has been found. 相似文献
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The main goal of this work is the generation of a new force field data set to the interaction of several gases such as H2, O2, N2, CO, H2O, and H2S with alkali cation-doped carbon nanotubes (CNTs) using ab initio calculations at the MP2(full)/6-311++G(d,p) level of theory. Different alkali cations including Li+, Na+, K+ and Cs+ were used to dope in the CNT. The calculated potential energy curve for the interaction of each gas molecule with each alkali cation-doped CNTs was fitted to an analytical potential function to obtain the parameters of the potential function. A modified Morse potential function was selected for the fitting in which the electrostatic interactions has been accounted by adding the β/r term to the Morse potential. The accuracy of the calculated force field was checked via Grand Canonical Monte Carlo (GCMC) simulation of the H2 adsorption on Li-doped graphite and Li-doped CNT. The results of these simulations were compared with the experimental measurements and the closeness of the simulation results with the experimental data indicated the accuracy of the proposed force field. The main merit of this work is the derivation of a specific force field for interaction of each of six gases with four alkali cation-doped CNT, which can be used in molecular simulation of these 24 of systems. The simulation results showed the increase of the H2 adsorption capacity of nanotube and graphite up to 50% and 10%, respectively, due to the insertion of Li ions. 相似文献