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101.
102.
Reinhart Ahlrichs 《Theoretical chemistry accounts》1976,41(1):7-15
It is proven that the total energy of interacting molecular systems A and B at large intermolecular distancesR can be expanded in a semi-convergent series in powers of 1/R. It is further proven that exchange forces vanish faster than any power of 1/R. 相似文献
103.
(?)-(R)-4,4,4,4′,4′,4′-Hexafluorovaline hydrochloride ((R)- 5 ) of 98% ee is prepared from β,β-bis(trifluoromethyl)acrylic acid (= benzyl 4,4,4-trifluoro-3-(trifluoromethyl)but-2-enoate; 1 ) in 4 steps with an overall yield of 9.6%. Key step is the separation of the TsOH salts of the diastereoisomers obtained by anti-Michael addition of (+)-(R)-1-phenylethylamine ( 2 ) to 1 (→ (R,R)- 3 ). In contrast to the published (S)-chirality, the X-ray structure analysis of (R,S)- 6 reveals, that (R)-chirality has to be assigned to the levorotatory (?)-4,4,4,4′,4′,4′-hexafluorovaline hydrochloride. 相似文献
104.
Stefan Brode Hans Horn Michael Ehrig Diane Moldrup Julia E. Rice Reinhart Ahlrichs 《Journal of computational chemistry》1993,14(10):1142-1148
A parallel direct SCF and gradient program for workstation clusters has been implemented on the basis of the ab initio program package TURBOMOLE. Applications on large molecular systems monitor an appreciable speedup in residence time. © John Wiley & Sons, Inc. 相似文献
105.
L. Pavesi D. Araujo Nguyen Hong Ky J. D. Ganiére F. K. Reinhart P. A. Buffat G. Burri 《Optical and Quantum Electronics》1991,23(7):S789-S804
A review of experimental results obtained by different techniques is presented on the problem of zinc diffusion. Zinc diffusion was carried out on Si-doped GaAs (n1018 cm–3) and on multiple quantum well (MQW) structures. The samples were investigated by secondary-ion mass spectroscopy (SIMS), different imaging modes of scanning electron microscopy such as secondary electrons, cathodoluminescence (CL) and electron beam-induced current (EBIC), transmission electron microscopy on a wedge-shaped specimen (WTEM) and by photoluminescence (PL). A nonexponential decay of the low-temperature EBIC signal accompanied by a very low CL signal due to the high density of nonradiative recombination centres were observed in the diffused region of the n-doped GaAs. Indeed, PL measurements demonstrate that Ga vacancies play a key role on the mechanism of the Zn diffusion. On the impurity-induced disordered (IID) MQW samples, an enrichment of Al at the surface was observed by SIMS and confirmed by WTEM and PL. Low-temperature PL spectra show the gradual disappearance of the MQW excitonic transitions as the number of disordered layers increases. When all of the MQW structure is destroyed, the band-to-band recombinations in the IID produced alloy dominate the PL spectrum. 相似文献
106.
1,2 exo-Diiodo-norbornane ( 4 ) was prepared from norcamphor hydrazone by oxidative iodination and subsequent rearrangement of the 2,2-diiodo-bicyclo [2.2.1]heptane ( 2 ). The stable α-iodohydrazone 11 was obtained from 1-iodo-bicyclo[2.2.1]heptan-2-one ( 10 ), which itself was prepared from 1-iodo-norbornene ( 5 ). Subsequent treatment of 11 with iodine lead to 1,2,2-triiodo-norbornane ( 12 ) and l,2-diiodo-norborn-2-ene ( 13 ). 1,2 endo-Diiodo-norbornane ( 14 ) was obtained by stereoselective reduction of 12 with tribtityltinhydride or by reaction of 13 with diimide. 相似文献
107.
The influence of electron correlation on reaction energies. The dimerization energies of BH3 and LiH
Reinhart Ahlrichs 《Theoretical chemistry accounts》1974,35(1):59-68
Results of rigorous computations employing extended Gaussian-type basis sets are reported for BH3, B2H6, LiH, and Li2H2 in their respective equilibrium geometries. The dimerization energy of BH3 is calculated as −20.7 kcal/mol within the Hartree-Fock approximation and as −36.6 kcal/mol if electron correlation is included.
The corresponding results for the dimerization of LiH are −47.3 kcal/mol and −48.3 kcal/mol. Partitioning of the correlation
energy contributions allows to attribute the effect of electron correlation to the increase of next neighbour bond interactions
on the dimerization of BH3 and LiH. The difficulties of accurate computations of reaction energies are discussed in detail. 相似文献
108.
Density functional theory calculations were carried out on the structurally characterized [(Cl(4)-cat)Mo(py)Fe(3)S(3) (CO)(4)(P(n)Pr(3))(3)], A, and (Cl(4)-cat)Mo(py)Fe(3)S(3)(CO)(6)(PEt(3))(2), B, and also on A(2)(-) and B(2+) clusters. The Fe-Fe distances in these molecules depend on the total number of valence electrons (60 e(-) in A and B(2)(+) and 62 e(-) in A(2)(-) and B) and undergo great structural changes upon addition or removal of electrons. The changes are consistent with known electron-counting rules in organometallic chemistry. The weak nature of the Fe-Fe bonding interactions in these clusters is apparent in the very similar energies of states with widely different Fe-Fe distances. 相似文献
109.
Jing Wang Rgine Guidetti-Grept Reinhart Keese Helen Stoeckli-Evans 《Helvetica chimica acta》1997,80(4):1169-1175
N, N-Dimethylformamide dimethyl acetal transforms an allylic OH group, which is part of a tetracyclic hydrocarbon in a unique elimination reaction into a [5.5.5.5]fenestradiene ( 2b → 4 ). In topologically selective reactions of this diene 4 with [Fe2(CO)9,], the [Fe(CO)4(η2-diene)] and the [Fe(CO)3(η4-diene)] complexes 8 and 9 , respectively, are formed by complexation on one side of the diene moiety, whereas complexation on the other side leads to a [Fe(CO)2(Cp)] complex 10 . 相似文献
110.
Renate Horbelt Stefanie Ebert Vaidvile Ulbikaite Giso Hahn Reinhart Job Barbara Terheiden 《固体物理学:研究快报》2016,10(7):515-519
The reduction of void formation in local Al contact structures is of high interest in studies dealing with passivated emitter and rear contact (PERC) solar cells. So far, several processing parameters and their impact on local contact formation were investigated in detail. However, up to now density variation of Al in dependence on temperature and Si content in the melt were not taken into account as a principal reason for void formation. In this context the current assumption of a constant volume of the Al paste particles is discussed in more detail. Based on the results of energy dispersive X‐ray spectroscopy, void formation implies either an expansion of paste particles or their burst during contact formation.