Covalent binding parameters and the ground state wavefunctions of vanadyl ion complexes

The Steven’s method of molecular orbitals for octahedral complexes containing transition metal ions has been used for estimating the binding parameters and interpreting theg factors of VO ₂ ⁺ ion in single crystals. The expressions forg factors have been given in terms ofK _‖ andK _⊥ taking into account the tetragonal crystalline field and covalent binding effects. Computations show thatK _⊥ should be less than 0.066 in order to fit the experimentalg values. The ground state wave function (GSWF) of VO ₂ ⁺ ion doped in different single crystals has been estimated using crystal field theory. The GSWF is found to be ind _xy state with slight admixture of the excited states ,d _xz andd _yz. The hyperfine interaction parameterP and Fermi contact termX have also been estimated.     

0++三胶子标胶球与QCD求和规则

计算了0⁺⁺三胶子标量流的两点函数,其中计及了直至量纲为6的凝聚项的贡献.在＂零宽度共振态加连续谱＂的谱函数模型中,得到了0⁺⁺三胶子标胶球的量子色动力学求和规则,由此定出了该标胶球的质量.     

Parallel processing forab initio total energy pseudopotential calculations

Summary The total energy pseudopotential method is well suited to parallel processing. This paper discusses a procedure for calculating the valence electronic wavefunction in a given ionic configuration, and considers the exploitation of parallel processing using a data parallel approach. The implementation of this procedure on two message passing i860 based machines, containing up to 64 nodes, is described, and the prospects for massively parallel execution are examined.     

Tb~(3+):LaBr_3能级分析

本文对Ln~(3+):LaCl_3和Ln~(3+):LaBr_3体系进行晶场能级分析,其主要目的有二:(一)对已测得的实验能级进行理论计算和归宿;(二)探讨能级间的相互作用及等价算符方法和不可约张量方法对该体系的适合程度。理论计算采用投影算符方法构成J=6,5,4,3,2,1,0的D_(3h)不可约表示基矢。在整个计算过程中,晶场矩阵由相同不可约表示的基矢构成。对~7F(J=6,5,4,3,2,1,0)本文分别应用等价算符方法(略去晶场J相互作用即略去所谓的晶场J混合作用)和不可约张量方法(考虑晶     

Hydrogen and Halogen Bonding in Homogeneous External Electric Fields: Modulating the Bond Strengths

Recent years have witnessed various fascinating phenomena arising from the interactions of noncovalent bonds with homogeneous external electric fields (EEFs). Here we performed a computational study to interpret the sensitivity of intrinsic bond strengths to EEFs in terms of steric effect and orbital interactions. The block-localized wavefunction (BLW) method, which combines the advantages of both ab initio valence bond (VB) theory and molecular orbital (MO) theory, and the subsequent energy decomposition (BLW-ED) approach were adopted. The sensitivity was monitored and analyzed using the induced energy term, which is the variation in each energy component along the EEF strength. Systems with single or multiple hydrogen (H) or halogen (X) bond(s) were also examined. It was found that the X-bond strength change to EEFs mainly stems from the covalency change, while generally the steric effect rules the response of H-bonds to EEFs. Furthermore, X-bonds are more sensitive to EEFs, with the key difference between H- and X-bonds lying in the charge transfer interaction. Since phenylboronic acid has been experimentally used as a smart linker in EEFs, switchable sensitivity was scrutinized with the example of the phenylboronic acid dimer, which exhibits two conformations with either antiparallel or parallel H-bonds, thereby, opposite or consistent responses to EEFs. Among the studied systems, the quadruple X-bonds in molecular capsules exhibit remarkable sensitivity, with its interaction energy increased by −95.2 kJ mol⁻¹ at the EEF strength 0.005 a.u.     

Direct Visualisation of the Surface Atomic Active Sites of Carbon-Supported Co3O4 Nanocrystals via High-Resolution Phase Restoration

The atomic arrangement of the terminating facets on spinel Co₃O₄ nanocrystals is strongly linked to their catalytic performance. However, the spinel crystal structure offers multiple possible surface terminations depending on the synthesis. Thus, understanding the terminating surface atomic structure is essential in developing high-performance Co₃O₄ nanocrystals. In this work, we present direct atomic-scale observation of the surface terminations of Co₃O₄ nanoparticles supported on hollow carbon spheres (HCSs) using exit wavefunction reconstruction from aberration-corrected transmission electron microscopy focal-series. The restored high-resolution phases show distinct resolved oxygen and cobalt atomic columns. The data show that the structure of {100}, {110}, and {111} facets of spinel Co₃O₄ exhibit characteristic active sites for carbon monoxide (CO) adsorption, in agreement with density functional theory calculations. Of these facets, the {100} and {110} surface terminations are better suited for CO adsorption than the {111}. However, the presence of oxygen on the {111} surface termination indicates this facet also plays an essential role in CO adsorption. Our results demonstrate direct evidence of the surface termination atomic structure beyond the assumed stoichiometry of the surface.     

Abelian-Higgs phase of SU(2) QCD and glueball energy

It is shown that SU(2) QCD admits an dual Abelian-Higgs phase, with a Higgs vacuum of a type-Ⅱ superconductor. This is done by using a connection decomposition for the gluon field and the random-direction approximation. Using a bag picture with soft wall, we presented a calculational procedure for the glueball energy based on the recent proof for wall-vortices [Nucl. Phys. B 741(2006)1].     

Geometric H/D isotope effects and cooperativity of the hydrogen bonds in porphycene.

We investigate the primary, secondary, and vicinal hydrogen/deuterium (H/D) isotope effects on the geometry of the two intramolecular hydrogen bonds in porphycene. Multidimensional potential energy surfaces describing the anharmonic motion in the vicinity of the trans isomer are calculated for the different symmetric (HH/DD) and asymmetric (HD) isotopomers. From the solution of the nuclear Schr?dinger equation the ground-state wavefunction is obtained, which is further used to determine the quantum corrections to the classical equilibrium geometries of the hydrogen bonds and thus the geometric isotope effects. In particular, it is found that the hydrogen bonds are cooperative, that is, both expand simultaneously even in the case of an asymmetric isotopic substitution. The theoretical predictions compare favorably with NMR chemical-shift data.     

Radial dependence of exterior electron distributions of molecular orbitals

A molecular surface is introduced to divide interior electron densities from exterior electron densities (EED). The radial distribution of EED (RADEED) is defined for each molecular orbital as a function of the distance from the molecular surface. Logarithmic plots of RADEED for NH₃ using various basis sets in ab initio MO calculations revealed some important features: (i) the Hartree-Fock limit for the orbital function tail may be suggested and thus qualities of basis sets can be discussed, and (ii) the slope of the curve shows the decay rate of the orbital which can be compared with the curve derived from the theoretical behavior of the long-range asymptotic form involving either the lowest ionization potential or the orbital energy of the highest occupied orbital.Dedicated to Professor J. Koutecký on the occasion of his 65th birthday