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1.
Methylthio- (MTE) and bis-methylthioethyne (BMTE) molecules are calculated by the SCF MO method (geometry optimization, basis
set 6–31G*/MP2). The calculated internal rotation barriers of methyl groups are 7.12 kJ/lmole for MTE and 12.86 kJ/mole for
BMTE (both groups are simultaneously rotated). The s-gosh-orientation of the thiomethyl fragments corresponds to a stable
conformation of BMTE. The estimated values of the s-cis- and s-trans-barriers of mutual rotation of SCH3 groups about the axis of the C≡C bond are 13.61 and 12.54 kJ/mole, respectively. Conformationally sensitive MOs and vibration
frequencies are established. An analysis of the experimental IR absorption and Raman spectra and the calculated vibrational
spectrum makes it possible to conclude that in the liquid phase the BMTE molecules also have an s-gosh-conformation.
Translated fromZhumal Strukturnoi Khimii, Vol. 39, No. 4, pp. 602–609, July–August, 1998. 相似文献
2.
Kaupp M Patrakov A Reviakine R Malkina OL 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(9):2773-2782
The characteristic dependence of J(31P,31P) spin-spin coupling constants of alkali metal tetraphosphane-1,4-diides on structure and composition has been analyzed by density functional methods. The computations confirm that the structure of the contact ion pairs is conserved in solution. Calculations on model systems M2P4H4, on naked P4H4(2-) anions, and on models including point charges, show that the role of the cations is mainly structural and to a smaller extent electrostatic. Three of the four J(P,P) coupling constants depend characteristically on the conformation of the anion, which in turn is determined by the substituents R and by cation-anion interactions. Several couplings exhibit a large through-space component and are thus strongly dependent on the relative orientation of nonbonding electron pairs on the phosphorus atoms involved. This is shown by visualization of coupling pathways using the recently introduced coupling energy density (CED), in combination with the electron localization function (ELF). 相似文献
3.
Making use of the fractional differential operator, we impose and study a new class of analytic functions in the unit disk (type fractional differential equation). The main object of this paper is to investigate inclusion relations, coefficient bound for this class. Moreover, we discuss some geometric properties of the fractional differential operator. 相似文献
4.
5.
Malkin E Repiský M Komorovský S Mach P Malkina OL Malkin VG 《The Journal of chemical physics》2011,134(4):044111
The effect of a finite size model for both the nuclear charge and magnetic moment distributions on calculated EPR hyperfine structure have been studied using a relativistic four-component method based on density functional theory. This approach employs a restricted kinetically balanced basis (mDKS-RKB) and includes spin-polarization using noncollinear spin-density exchange-correlation functionals in the unrestricted fashion. Benchmark calculations have been carried out for a number of small molecules containing Zn, Cd, Ag, and Hg. The present results are compared with those obtained at the Douglas-Kroll-Hess second order (DKH-2) method. The dependence of the results on the quality of the orbital and auxiliary basis sets has been studied. It was found that some basis sets contain irregularities that deteriorate the results. Especial care has to be taken also on the construction of the auxiliary basis for fitting the total electron and spin-densities. 相似文献
6.
V. Ya. Aleshkin S. A. Akhlestina B. N. Zvonkov N. B. Zvonkov I. G. Malkina E. A. Uskova 《JETP Letters》1998,68(1):91-96
A new method of obtaining quantum-size GaAs1−x
Sbx (x⩽0.45) layers is proposed. The method consists in laser vaporization of solid metallic antimony near the substrate directly
in the reactor. The antimony concentration is set by the antimony sputtering time with the arsine flux shut off. The polarization
of the photoluminescence of the obtained layers indicates the formation of quantum wires. The heterostructures obtained are
used to fabricate laser diodes.
Pis’ma Zh. éksp. Teor. Fiz. 68, No. 1, 84–88 (10 July 1998) 相似文献
7.
G. M. Petrova N. P. Bednyagina T. G. Malkina V. N. Podchainova 《Chemistry of Heterocyclic Compounds》1971,4(4):520-522
1-(Alkyl benzimidazolyl)-, 1-benzothiazolyl- and 1-benzoxazolyl-3-methyl-5-phenylformazans containing sulfo groups (in the meta or para position) in the phenyl residue have been synthesized. It has been established that some of them can be used as analytical reagents.For part XXI, see [5]. 相似文献
8.
Yu. L. Frolov A. V. Vashchenko V. I. Smirnov A. G. Malkina B. A. Trofimov 《Journal of Structural Chemistry》2008,49(3):395-398
This paper reports on our quantum-chemical analysis of the nucleophilic substitution of the bromine atom by the cyano group in the reaction of methylbromoacetylene with copper cyanide. According to calculations, the reaction can form a four-membered ring containing a copper atom. 相似文献
9.
Komorovský S Repiský M Malkina OL Malkin VG Malkin Ondík I Kaupp M 《The Journal of chemical physics》2008,128(10):104101
A new relativistic four-component density functional approach for calculations of NMR shielding tensors has been developed and implemented. It is founded on the matrix formulation of the Dirac-Kohn-Sham (DKS) method. Initially, unperturbed equations are solved with the use of a restricted kinetically balanced basis set for the small component. The second-order coupled perturbed DKS method is then based on the use of restricted magnetically balanced basis sets for the small component. Benchmark relativistic calculations have been carried out for the (1)H and heavy-atom nuclear shielding tensors of the HX series (X=F,Cl,Br,I), where spin-orbit effects are known to be very pronounced. The restricted magnetically balanced basis set allows us to avoid additional approximations and/or strong basis set dependence which arises in some related approaches. The method provides an attractive alternative to existing approximate two-component methods with transformed Hamiltonians for relativistic calculations of chemical shifts and spin-spin coupling constants of heavy-atom systems. In particular, no picture-change effects arise in property calculations. 相似文献
10.
Hrobárik P Reviakine R Arbuznikov AV Malkina OL Malkin VG Köhler FH Kaupp M 《The Journal of chemical physics》2007,126(2):024107
The calculation of nuclear shieldings for paramagnetic molecules has been implemented in the ReSpect program, which allows the use of modern density functional methods with accurate treatments of spin-orbit effects for all relevant terms up to order Omicron(alpha4) in the fine structure constant. Compared to previous implementations, the methodology has been extended to compounds of arbitrary spin multiplicity. Effects of zero-field splittings in high-spin systems are approximately accounted for. Validation of the new implementation is carried out for the 13C and 1H NMR signal shifts of the 3d metallocenes 4VCp2, 3CrCp2, 2MnCp2, 6MnCp2, 2CoCp2, and 3NiCp2. Zero-field splitting effects on isotropic shifts tend to be small or negligible. Agreement with experimental isotropic shifts is already good with the BP86 gradient-corrected functional and is further improved by admixture of Hartree-Fock exchange in hybrid functionals. Decomposition of the shieldings confirms the dominant importance of the Fermi-contact shifts, but contributions from spin-orbit dependent terms are frequently also non-negligible. Agreement with 13C NMR shift tensors from solid-state experiments is of similar quality as for isotropic shifts. 相似文献