Mean amplitudes of vibration in some tetrahedral tetrahalogeno complexes

The Cyvin method, utilizing symmetry coordinates, has been employed here to compute the mean-square amplitude quantities, generalized mean-square amplitudes (mean-square parallel amplitudes, mean-square perpendicular amplitudes and mean cross products) and mean amplitudes of vibration for the bonded as well as non-bonded atom pairs at the temperaturesT=298°K andT=500°K for the tetrahedral tetrahalogeno complexes of zinc, cadmium, gallium, indium, thallium and arsenic. The non-linear behaviour of the mean amplitudes of vibration in terms of the electronegativities of the central atoms has been discussed, followed by a discussion on the replacement of peripheral atoms.     

Molecular orbital calculation of some vibrational properties of the complex between HCN and HF

Ab initio LCAO-SCF calculations with an extended basis set are used to predict the geometry and various vibrational properties of the hydrogen bonded complex between HCN and HF. The complex is predicted to be completely linear, HF being the proton donor. The frequencies of the intermolecular vibrations are in good agreement with experiment. The intramolecular frequency shifts and absorption intensity changes are also determined. The large increase in the intensity of the HF stretching frequency in the complex is found to be due to both charge transfer and polarization forces.     

EPR spectra of C60 anions

The broad and sharp EPR signals observed in spectra of C₆₀ and C ₆₀ ^3? are summarized and proposed assignments are discussed. The sharp signals in samples of C ₆₀ ^2? are reviewed.     

Manganese or chromium doping effects in BaTiO3: Molecular orbital model for epr and optical spectra

Abstract

The EPR fine and hyperfine tensors of Mn and Cr ions in cubic and tetragonal BaTiO₃ have been calculated according to their positions in the oxygen octaedron surroundings using the molecular MS Xα method.     

Russian measurements of neutron energy spectra on the Mir orbital station

Results of the experiments on neutron energy spectra measurements within broad energy range from 5 x 10(-7) to 2 x 10(2) MeV aboard the Mir orbital station and equivalent neutron dose estimation are presented. Four measurement techniques were used during the experiments. The shape of spectra and their absolute values are in good agreement. According to those experiments, an equivalent neutron dose depends upon effective shielding thickness and spacecraft mass. The neutron dose mentioned is comparable with that of ionizing radiation. Neutron flux levels measured aboard the Mir station have shown that a neutron spectrometer involving broad energy range will be used within the radiation monitoring systems in manned space flights.     

阿比特龙的红外光谱与前线轨道

采用密度泛函理论的B3LYP混合泛函和6-311G(d,p)基组,通过几何结构优化得到了阿比特龙分子的稳定构型.计算了阿比特龙分子的红外吸收光谱,并与文献数据进行比较,将2971.01、1588.31、1536.13、1450.40、1112.13和1074.44 cm~(-1)等处吸收峰指认为特征吸收峰.在优化计算的基础上,结合Multiwfn软件分析了阿比特龙分子的前线轨道成分,得出阿比特龙分子的亲核能力明显强于其亲电能力,C55、O54原子在95αHOMO中占据的权重分别为61.79%和17.05%,C=O-H部位是其亲核反应的活性中心.研究结果对阿比特龙分子的检测、活性应用等方面具有一定的理论指导意义.     

Photoemission spectra of LaMnO3 controlled by orbital excitations

We investigate the spectral function of a hole moving in the orbital-ordered ferromagnetic planes of LaMnO3, and show that it depends critically on the type of orbital ordering. While the hole does not couple to the spin excitations, it interacts strongly with the excitations of e(g) orbitals (orbitons), leading to a new type of quasiparticle with a dispersion on the orbiton energy scale and with strongly enhanced mass and reduced weight. Therefore we predict a large redistribution of spectral weight with respect to the bands found in local density approximation (LDA) or in LDA+U.     

Molecular orbital theory of aromatic ring currents

The London theory of the diamagnetic susceptibility of conjugated hydrocarbons is extended in a manner which leads to detailed information about the distribution of interatomic currents induced by a general magnetic field. The method is illustrated by a calculation of the currents flowing round the two closed rings of azulene in a uniform field. This suggests that the larger current flows in the five-membered ring.     

The electron spin resonance spectra of the toluene,p-xylene and m-xylene anions

The electron spin resonance (e.s.r.) spectra of the anions of toluene, p-xylene and m-xylene have been studied and the proton hyperfine coupling constants determined. These are in excellent agreement with the predictions of Hückel molecular orbital theory.     

A microscopic description of the vibrational spectra in even spherical nuclei

The previously developed multiphonon method is applied to the study of the quadrupole vibrational motion in even-even spherical nuclei. For the first time calculations with a model Hamiltonian containing pairing and quadrupole-quadrupole interactions are performed up to four phonons. The contributions of all the parts of the Hamiltonian are analyzed and it is shown that some terms generally omitted cannot be neglected.     

Simple molecular orbital theory interpretation of the photoelectron spectra of the azines ag

A modified Iterative Extended Hückel Method (MIEHM) is introduced and applied to the photoelectron spectra of benzene, pyridine, pyrazine, pyrimidine, pyridazine, s-triazine and s-tetrazine. Guided by comparison with available ab initio Hartree-Fock calculations, the molecular orbitals are divided into four categories. The correlation between calculated orbital energies and experimental ionization energies is then established separately for each group of orbitals, leading to a consistent interpretation of the first ten bands in the photoelectron spectra. The resulting assignment is in general agreement with the one proposed by Gleiter. Heilbronner and Hornung⁴ on the basis of empirical correlation procedures.