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151.
The method of diatomics-in-molecules (DIM) is applied to the FH2 system. With spin—orbit interaction neglected, all elements of the 24 × 24 hamiltonian matrix are tabulated as analytic functions of the six diatomic fragment potential curves. It is found that neglect of off-diagonal 8 × 8 blocks in the DIM hamiltonian matrix leads to an energy expression for the ground 1 2A′ level which is identical to the valence-bond formula used by Blais and Truhlar in dynamical studies of the F + D2 reaction. The 2A″ excited level from DIM theory is identical to the result derived by Blais and Truhlar, without neglect of the 8 × 8 off-diagonal blocks. The DIM and simple valence-bond energies are compared numerically for noncollinear geometries. 相似文献
152.
Robert G. Hayes 《Chemical physics letters》1976,38(3):463-466
We have examined the dependence of the photoelectric cross section from individual atomic orbitals and from groups of orbitals adapted to crystal symmetries in order to ascertain the relevance of this effect to the photoelectron spectra arising from single crystals. 相似文献
153.
A new method to compute intermolecular energies in non-bonding regions is presented. It is based on the assumption that in such regions molecules can be reviewed as the sum of distorted, possibly overlapping, and electron exchanging atoms. The intermolecular energy change at a given distance is due to the sum of the atomic energy changes caused by these distortions. The energy change of any particular atom is computed in a Hartree—Fock model in which the effect of the other atom is represented by an effective potential. This potential in turn is computed from a calculation at a slightly larger intermolecular distance of the potential seen by an external electron in the field of the “other” atom. This potential computed in the RPA approximation and involves the distorted Hartree—Fock orbitals of the other atom (computed in a similar manner to the above) and the RPA response function of the other distorted atom. 相似文献
154.
Different methods for representing the upper orbitals in Rydberg transitions are tested by means of a series of ab initio SCF and CI calculations for ethylene and various properties for such diffuse united-atom species are reported. Calculated transition energies indicates the maximum separation between individual components of the (π,3d) Rydberg species to be in the 0.1-0.2 range, with similarly small energy separations being obtained for the corresponding (π, 3p) states 相似文献
155.
Gottfried Lichti Brian S. Hawkett Robert G. Gilbert Donald H. Napper David F. Sangster 《Journal of polymer science. Part A, Polymer chemistry》1981,19(4):925-938
Data are presented on the time evolution of particle-size distributions (PSDs) in seeded and ab initio styrene emulsion polymerization systems. Initiation was by chemical reagent (potassium persulfate) or γ-radiation. The unswollen PSDs at various times during interval II of the polymerization were obtained by direct measurement of calibrated electron micrographs. Experimental results were fitted with the equations that describe the time evolution of an initial PSD. Analytic solutions to these equations that allow for entry, exit, and propagation of free radicals were obtained. The values of the rate coefficients for these processes used to fit the experimental data were in excellent agreement with those obtained from dilatometric kinetics experiments. 相似文献
156.
The reactions of 2,3-dihydrothiazolo[2,3-b]benzothiazolium bromide 1 (A? ?Br?) with certain nucleophilic reagents have been performed for the purpose of ascertaining the reaction pathways and identifying the group that is displaced from the central carbon atom of the dithiocarbamate system. The nature of complex salt-like intermediates formed initially from 1 (A? ?Br?) has been studied and confirmed. For comparison, a number of nucleophilic substitution reactions of 2-methylthio-3-methylbenzothiazolium iodide 17 and 2-dimethylamino-3-methylbenzothiazolium perchlorate 18 have been examined. 相似文献
157.
Multi-residue method for the determination of chlorinated phenol metabolites in urine 总被引:1,自引:0,他引:1
Thomas R. Edgerton Robert F. Moseman Ralph E. Linder Lynn H. Wright 《Journal of chromatography. A》1979,170(2):331-342
Electron-capture-gas chromatographic (EC-GC) methods for the determination of chlorinated phenol metabolites of hexachlorobenzene (HCB) and pentachlorophenol (PCP) in urine are presented. After extraction the sample was reacted with diazomethane to produce the methyl ether of each metabolite prior to determination by EC-GC. An acid alumina column was used for cleanup and separation of methylated phenols into groups. Average recoveries of greater than 80% were obtained from urine fortified with known amounts of the phenol metabolites under investigation. A level of 1 ppb1 was established as minimum detection limit for each phenol metabolite. Previously unreported urinary metabolites of HCB and PCP were found as a result of a rat feeding study. Levels of chlorinated phenol residues from (a) human general population and (b) a worker occupationally exposed to PCP are also included. 相似文献
158.
Robert Faure 《Annali di Matematica Pura ed Applicata》1985,140(1):365-381
Sommaire Dans cette étude, d'une part à partir de résultais antérieurs éablis par l'aueur on démonire un théorème concernant l'interaction par choc entre deux oscillations non linéaires avec synchronisation. Puis d'autre part on généralise dans le cas des excitations par des percussions presque périodiques (définition de Schwartz) la méthode de la moyenne pour les système d'oscillateurs non linéaires; ainsi que le cas des solutions voisines des positions d'équilibre. Ces résultats connaissent des applications en Mécanique. 相似文献
159.
John A. Montgomery James R. Piper Robert D. Elliott Eugene C. Roberts Carroll Temple Y. Fulmer Shealy 《Journal of heterocyclic chemistry》1979,16(3):537-539
Eighteen derivatives of 2,4-diamino-6-methylpteridine related to methotrexate and aminopterin have been prepared from 6-(bromomethyl)-2,4-pteridinediamine by nucleophilic displacement reactions. None of these compounds showed any antileukemic acitivity. 相似文献
160.
It is shown that a simple expression for the partial widths in a multichannel decay problem can be readily obtained from a Siegert wavefunction. 相似文献