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The anharmonic frequencies of fundamental vibrations, overtones, and combination vibrations, as well as the intensities of
absorption bands in the IR spectrum of uracil, are calculated. The anharmonic quartic force field and the third-order dipole
moment surface calculated by the DFT quantum-mechanical method (B3LYP/6-31+G(d,p)) are taken as the initial parameters. The anharmonic frequencies and intensities of vibrations are determined using the
second-order perturbation theory in the form of contact transformations. Multiple Fermi resonances and polyads are determined
by the diagonalization of a small interaction matrix of vibrations of different types (fundamental, combination, and overtone
frequencies). The total experimental IR spectrum of matrix-isolated uracil is interpreted. It is shown that the used method
of calculating anharmonic frequencies and intensities can form a basis for anharmonic calculations of vibrations of moderate
molecules. 相似文献
57.
Elena Couselo Santos González Victor Markov Consuelo Martínez Alexander Nechaev 《Linear algebra and its applications》2010,433(2):356-364
We continue here the research on (quasi)group codes over (quasi)group rings. We give some constructions of [n,n-3,3]q-codes over Fq for n=2q and n=3q. These codes are linearly optimal, i.e. have maximal dimension among linear codes having a given length and distance. Although codes with such parameters are known, our main results state that we can construct such codes as (left) group codes. In the paper we use a construction of Reed-Solomon codes as ideals of the group ring FqG where G is an elementary abelian group of order q. 相似文献
58.
G. O. Karpov E. V. Bermesheva A. V. Zudina A. F. Asachenko L. I. Minaeva M. A. Topchiy P. S. Gribanov M. S. Nechaev M. V. Bermeshev 《Doklady Chemistry》2018,479(2):49-52
New high-performance catalytic systems based on Pd N-heterocyclic carbene complexes for the selective addition polymerization of 5-ethylidene-2-norbornene (ENB) were proposed. With these catalysts, polymerization can be conducted at unprecedentedly high monomer/catalyst ratio (up to 5 × 105/1) and gives high-molecular-weight soluble polymers with good film-forming properties. Varying the polymerization conditions (reaction temperature, monomer and catalyst concentrations, monomer/Pd ratio) makes it possible to prepare soluble ENB-based addition polymers with specified molecular weights in reasonable yields. 相似文献
59.
Khrustalev VN Portnyagin IA Nechaev MS Bukalov SS Leites LA 《Dalton transactions (Cambridge, England : 2003)》2007,(32):3489-3492
Equatorial-axial isomerism of the tin(II)-iron(0) complex (Me2NCH2CH2O)2Sn-Fe(CO)4 (), which indicates that the free Sn(OCH2CH2NMe2)2 () ligand can behave as a stannylene, has been revealed and studied by NMR and IR spectroscopy in solution as well as by Raman spectroscopy and X-ray diffraction analysis in the solid-state. 相似文献
60.
We study the dynamics of a Rouse polymer chain which diffuses in a three-dimensional space under the constraint that one of its ends, referred to as the slip-link, may move only along a one-dimensional line containing randomly placed, immobile, perfect traps. Extensions of this model occur naturally in many fields, ranging from the spreading of polymer liquids on chemically active substrates to the binding of biomolecules by ligands. For our model we succeed in computing exactly the time evolution of the probability P
sl(t) that the chain slip-link will not encounter any of the traps until time t and, consequently, that until this time the chain will remain mobile. 相似文献