Frequency-dependent hyperpolarizabilities of the Ne, Ar, and Kr atoms using the approximate coupled cluster triples model CC3

The frequency-dependent electric field-induced second harmonic generation (ESHG) second hyperpolarizabilities gamma of neon, argon, and krypton are calculated using the approximate coupled cluster triples model CC3. Systematic basis set investigations are carried out to establish basis set limits, and scalar relativistic effects are accounted for by direct perturbation theory. To estimate higher-order correlation effects, full configuration-interaction results are used to benchmark the accuracy of CC3. The best theoretical estimates obtained thereby for the static second hyperpolarizabilities gamma(0) are 107.4, 1159, and 2589 a.u. for neon, argon, and krypton, respectively. These values as well as the results for the dispersion curve of the parallel component gamma( parallel) agree well with the latest experimental values from electric field-induced second harmonic generation. In addition, the dispersion of the perpendicular component gamma( perpendicular) and the hyperpolarizability ratios gamma( parallel)gamma( perpendicular) has been studied for the first time on a consistently correlated ab initio level. The analysis of the results indicates that, in particular for neon and krypton, the presently available experimental values are flawed.     

1S core-level shifts of Al and Ar atoms in aluminum clusters

Theoretical 1s core-electron binding energies are presented for Al and Ar atoms in free space and in AlAl₁₂, AlAl₁₂Al₆, and ArAl₁₂ clusters. The binding energies have been calculated by the self-consistent field Xα scattered-wave (SCF Xα SW ) method using various exchange parameters and different atomic-sphere overlaps. The atom/cluster binding-energy shifts have been obtained both from the Slater's transition-state energies and from the total-energy differences; these values are in better agreement with each other if calculated with proper overlapping than if with nonoverlapping spheres. A comparison with available experimental and theoretical data is given as well.     

Electronic structure of Al,P, S,and Cl impurities in silicon

We report a fully self-consistent investigation of the electronic structure, relation between charge transfer and electronegativity, bonding characteristics, and alloying of Al, P, S, and Cl with silicon. The present study indicates that the charge transfer from the host Si atoms to the central impurity atom increases with electronegativity of the impurity element. The bonding between host Si atoms and the impurity atoms is ionic in nature. © 1996 John Wiley & Sons, Inc.     

On the use of frozen orbitals in molecular orbital cluster calculations: Cl on Si(111)

By using the corresponding orbital transformation a quantitative criterion is found for the MOs that can be kept fixed during calculations using a perturbative SCF procedure. Results obtained keeping fixed a subset of molecular orbitals are quantitatively in agreement with those obtained by using the canonical SCF procedure but with a considerable saving of computer time in the SCF step.     

X射线荧光光谱法测定洗衣粉中硅、铝、磷、硫的初步研究

用X射线荧光光谱法测定了洗衣粉中硅，铝，磷，硫的含量，并与化学法进行了比较。结果表明，本法样品处理简单，分析速度快，可用于快速确定洗衣粉的化学成分。     

含磷、硫、氮配原子的钴羰基簇合衍生物的合成和表征

过渡金属原子簇化学是当今化学学科中非常活跃的研究领域之一 ,这类簇合物大多有着新颖的几何构型和多样化的成键方式 ,并且具有独特的催化性能[1 ] 。迄今为止 ,人们合成了多种含磷、硫、氮等原子的铁、钴、钌等羰基簇合衍生物 ,但其中三种以上原子同时配位的情况并不多见 ,有金振兴等的含Ｃ、Ｓ、Ｎ配原子的三核钴簇[2 ] ;Ｌｕｇａ和Ｃａｂｅｚａ的三钌簇[3 ,4] 以及Ｃｈｉｈａｒａ等合成的五核钌簇[5] ,其分子中都有Ｐ、Ｎ、Ｏ三原子配位。我们利用复杂的含Ｐ、Ｓ、Ｎ等可配原子的有机配前体与二元钴羰合物反应 ,合成了一系列三核、四核…     

Theoretical studies on the inner-sphere reorganization energies for the self-exchange reactions of gas-phase diatomic molecules HA (A = Mg,Al, Si,P, S,Cl)

On the basis of the recently proposed accurate calculation scheme of the inner-sphere reorganization energies (RE ) of the reactants in gas-phase electron-transfer xprocesses, the inner-sphere RE values for the AH + AH⁺ (A = Mg, Al, Si, P, S, Cl) self-exchange systems are calculated in terms of an ab initio Hartree–Fock self-consistent-field MO method at different basis-set levels (6-31G **, 6-31 +G **, DZ , and DZP ). The structural parameters involved are also determined via the perturbation theory and the Dunham expansion of the Morse function and compared with the experimental values. Dissociation energies are corrected by electron correlation at the MP 2/6-31G * level. Results of the inner-sphere REs obtained from different models via ab initio calculations for these systems discussed here are in full agreement with the corresponding experimental data. © 1995 John Wiley & Sons, Inc.     

Au12M (M=Na,Mg, Al,Si, P,S, Cl)团簇的结构、稳定性和电子性质

采用基于密度泛函理论的第一性原理方法系统地研究了Au12M(M=Na,Mg,Al,Si,P,S,Cl)团簇的结构、稳定性和电子性质.对团簇的平均结合能、镶嵌能、垂直离化势、最高占据分子轨道(HOMO)和最低未占据分子轨道(LUMO)的能级差、电荷布居分析、自然键轨道(NBO)进行了计算和讨论.对于Au12M(M=Na,Mg,Al)团簇,它们形成了内含M原子的最稳定的笼状结构.然而对于Au12M(M=Si,P,S,Cl)团簇,它们却形成了以M元素为顶点的稳定锥形结构.在这些团簇中发现Au12S团簇相对是最稳定的,这是由于Au12S团簇形成了稳定的满壳层的电子结构.自然电荷布居分析表明:对于所有的Au12M(M=Na,Mg,Al,Si,P,S,Cl)团簇电荷总是从Au原子转向M原子.自然键轨道和HOMO分析表明Au12M团簇中发生了Au原子的s-d轨道和M原子的p轨道间的杂化现象.     

Hydrogen bridging in the compounds X2H (X=Al,Si,P,S)

X2H hydrides (X=Al, Si, P, and S) have been investigated using coupled cluster theory with single, double, and triple excitations, the latter incorporated as a perturbative correction [CCSD(T)]. These were performed utilizing a series of correlation-consistent basis sets augmented with diffuse functions (aug-cc-pVXZ, X=D, T, and Q). Al2H and Si2H are determined to have H-bridged C2v structures in their ground states: the Al2H ground state is of 2B1 symmetry with an Al-H-Al angle of 87.6 degrees, and the Si2H ground state is of 2A1 symmetry with a Si-H-Si angle of 79.8 degrees. However, P2H and S2H have nonbridged, bent Cs structures: the P2H ground state is of 2A' symmetry with a P-P-H angle of 97.0 degrees, and the S2H ground state is of 2A' symmetry with a S-S-H angle of 93.2 degrees. Ground state geometries, vibrational frequencies, and electron affinities have been computed at all levels of theory. Our CCSD(T)/aug-cc-pVQZ adiabatic electron affinity of 2.34 eV for the Si2H radical is in excellent agreement with the photoelectron spectroscopy experiments of Xu et al. [J. Chem. Phys. 108, 7645 (1998)], where the electron affinity was determined to be 2.31+/-0.01 eV.     

The inner-sphere reorganization energies for AH2 + AH (A = Al,Si, P,S) electron self-exchange reactions in electron-transfer processes from ab initio calculations

This article presents an application of the accurate calculation scheme proposed recently for the inner-sphere reorganization energies of molecules of the type AH₂ (A = Al, Si, P, and S). A reasonable extension has been made. The inner-sphere reorganization energies for the title thermal electron self-exchange reactions are calculated in terms of ab initio MO self-consistent field method (HFSCF ) at different basis-set levels (6-31G **, 6-31 + G **, DZ , and DZP ) and the involved parameters are also determined. These calculated results have been calibrated by comparing optimized molecular geometrical parameters and corresponding energy properties with the experimental findings or other theoretical values. An approximation, in which the contribution from the bond length–bond angle to the potential energy surface is neglected, is adopted in constructing the calculation formulas via the function model. Its adequacy is discussed. Agreement among different calculation schemes is analyzed. © 1995 John Wiley & Sons, Inc.     

Bestimmung von Si,Cl, K,P, Ca und Al in biologischem Material durch Aktivierungsanalyse mit 14 MeV Neutronen

A neutron activation analysis procedure utilizing 14 MeV neutrons produced by an accelerator is described. The six elements Si, Cl, K, P, Ca and Al are determined in biological material without any chemical separation. For avoiding the interpretation of very complex spectra, the half-life of the nuclides was applied for the measurement as an important characteristic.      

DFT investigation of endohedral boron oxide nanocapsules: Encapsulation of He, Ne, Ar, H, N, and Cl atoms

The electronic structure and stabilization energy of spherical and pyramidal shapes of boron oxide nanocapsules (X@B₂₀O₃₀, X = He, Ne, Ar, H, N, Cl) were investigated by long-range and dispersion corrected density functional theory (DFT + Disp) including CAM-B3LYP, B3LYP-D3, ωB97X-D and B2PLYP-D methods. Based on these calculations, the formation of nanocapsules is an exothermic process (except for Cl@B₂₀O₃₀). The spherical boron oxide nanocapsules are mainly stabilized by dispersion, while the stability of pyramidal complexes is mainly due to monomer relaxation energy. The theoretical results obtained in this work show that the boron oxide capsule is a good potential candidate for gas storage.     

Theoretical Study on the Structure and Stability of Si5X （X = Li, Be, B, C, N, O, F, Na, Mg, Al, Si, P, S, Cl） Clusters

1 INTRODUCTION In the later 60s of last century, silicon substituted for germanium to present as mainstream in semicon- ductor. The semi-conductive devices made by silicon have many advantages, for example, refractory pro- perty, high radioresistance, simple and stable process- ing technic, high machinability and low cost. So it was widely used to manufacture large power appara- tuses, for instance, digit and linear integrated circuit, large scale integrated circuit (LSI), etc. Thus, th…     

The saddle point of the nucleophilic substitution reaction Cl− + CH3Cl: results of large-scale coupled cluster calculations

On the basis of large-scale coupled cluster calculations including connectedz triple substitutions in a perturbative way, the geometrical parameters of the D _{3 h} saddle point of the Walden inversion reaction Cl⁻ + CH₃Cl′→ ClCH₃ + Cl′⁻ are predicted to be R _s (C—Cl) = 2.301 ? and r _s (C—H) = 1.069 ?. The barrier height with respect to the reactants is recommended to be 11.5 ± 1.0 kJ mol⁻¹. Connected triple substitutions lower the barrier height by almost a factor of 2, but have very little influence on the geometric structure of the saddle point. Received: 26 June 1998 / Accepted: 15 July 1998 / Published online: 28 September 1998     

Determination of B,Si, P,S, Cl,and Br in uranium materials by inductively coupled plasma mass spectrometry

Efficient highly sensitive methods are proposed for the direct determination of nonmetallic impurities in uranium materials by inductively coupled plasma mass spectrometry (ICP-MS). The possibility for the elimination of polyatomic overlap interferences on the signals of ³²S and ³⁵Cl using high-resolution measurements (m/Δm = 4000) was demonstrated. The influence of the operation conditions of the mass spectrometer, such as plasma power and nebulizer gas flow rate, was investigated, and the effect of the uranium matrix on the analytical signal of the isotopes to be determined was studied. The detection limit and lower limit of the analytical range for B, Si, P, S, Cl, and Br in uranium materials were estimated. The developed procedures were certified as standard trade procedures and used at the Urals Electrochemical Integrated Plant for the quality control of uranium materials.     

A 3D-analysis of cluster formation and dynamics of the X(-)-benzene (X = F, Cl, Br, I) ionic dimer solvated by Ar atoms

The specific influence of X(-) ions (X = F,Cl, Br, I) in the solvation process of halide-benzene (X(-)-Bz) ionic heterodimers by Ar atoms is investigated by means of molecular dynamic (MD) simulations. The gradual evolution from cluster rearrangement to solvation dynamics is discussed by considering ensembles of n (n = 1-15 and n = 30) Ar atoms around the X(-)-Bz stable ionic dimers. The potential energy surfaces employed are based on an atom/ion-atom and atom/ion-bond decomposition, which has been developed previously by some of the authors. The outcome of the dynamics is analyzed by employing radial distribution functions (RDF) and tridimensional (3D) probability densities.     

Semiempirical calculations of hyperpolarizabilities for extended π systems: Polyenes,polyynes, and polyphenyls

The dipole moments (μ), polarizabilities (α), hyperpolarizabilities (β), and second-order hyperpolarizabilities (γ) of polyenes, polyynes, and polyphenyls have been calculated by a finitefield method with the PM -3 parameterization of the semiempirical MNDO Hamiltonian at the optimum geometries. These results were compared to experimental values obtained from EFISH and THG measurements. The calculations reproduce the magnitudes of β and γ, as well as the effect of the substituents and the effect of bond alternation on β and γ. The coefficients of the power law, which describes the dependence of β and γ on the number of π centers, were calculated. For β, exponents of 1.5–2.2 and 0.03–0.04 were obtained for polyenes and polyynes, respectively, and for γ, exponents of 3.9–4.9, 2.9–3.3, and 2.5–2.7 were obtained for polyenes, polyynes, and polyphenyls, respectively. These results confirm the efficiency of enhancing γ by insertion of C = C double bonds into a chain. © 1992 John Wiley & Sons, Inc.     

Basis set limit electronic excitation energies, ionization potentials, and electron affinities for the 3d transition metal atoms: Coupled cluster and multireference methods

Recently developed correlation consistent basis sets for the first row transition metal elements Sc-Zn have been utilized to determine complete basis set (CBS) scalar relativistic electron affinities, ionization potentials, and 4s(2)3d(n-2)-4s(1)d(n-1) electronic excitation energies with single reference coupled cluster methods [CCSD(T), CCSDT, and CCSDTQ] and multireference configuration interaction with three reference spaces: 3d4s, 3d4s4p, and 3d4s4p3d'. The theoretical values calculated with the highest order coupled cluster techniques at the CBS limit, including extrapolations to full configuration interaction, are well within 1 kcal/mol of the corresponding experimental data. For the early transition metal elements (Sc-Mn) the internally contracted multireference averaged coupled pair functional method yielded excellent agreement with experiment; however, the atomic properties for the late transition metals (Mn-Zn) proved to be much more difficult to describe with this level of theory, even with the largest reference function of the present work.