439 research outputs found
VIBRATIONAL ANHARMONICITY AND SCALING THE QUANTUM MECHANICAL MOLECULAR FORCE FIELD
No full text Yu. N. Panchenko, P. Pulay and F. T\""{o}r\""{o}k, J. Mol. Struct. 34, 283 (1976); V.I. Pupyshev, Yu.N. Panchenko, Ch. W. Bock and G. Pongor, J. Chem. Phys. 94, 1247 (1991); Yu. N. Panchenko, G.R. De Mar\'{e} and V.I. Pupyshev, J. Phys. Chem. 99, 17544 (1995); Yu. N. Panchenko, Moscow Univ. Chem. Bull. 51 (5), 23 (1996). D.M. Dennison, Rev. Mod, Phys. 12, 175 (1940); G.E. Hansen and D.M. Dennison, J. Chem. Phys. 20, 313 (1952).Author Institution: Laboratory of Molecular Spectroscopy, Division of Physical Chemistry, Department of Chemistry, M.V. Lomonosov Moscow State University; Laboratory of Molecular Structure and Quantum Mechanics, Division of Physical Chemistry, Department of Chemistry, M.V. Lomonosov Moscow State University; Chemistry Department, Philadelphia College of Textiles \& ScienceThe interrelationship between the scale factors obtained using Pulay's from the anharmonic and the harmonized vibrational frequencies of a light molecule and its heavy analogue is considered in terms of a Morse potential. The determination of the scale factors from the vibrational frequencies of a light molecule is shown to result in smaller deviations of the calculated and experimental vibrational frequencies of its heavy analogue than those of the reverse procedure. In this context the extent to which Dennison's is satisfied is also discussed
TRANSFERABILITY OF SCALE FACTORS VERSUS TRANSFERABILITY OF FORCE CONSTANTS
No full textA.G. Yagola, I.V. Kochikov, G.M. Kuramshina and Yu. A. Pentin. ``Inverse Problems of Vibrational Spectroscopy"". VSP, Utrecht, The Netherlands, 1999. Chapter 11, p. 259. Yu, N. Panchenko, J. Struct. Chem. 40, 548 (1999) (Russian pagination).Author Institution: Laboratory of Molecular Spectroscopy, Division of Physical Chemistry, Department of Chemistry, M.V. Lomonosov Moscow State UniversityIn the techniques for solving the inverse vibrational problem on the basis of quantum-mechanical force fields, it is assumed that the force constants are the same for quasi-equivalent coordinates in similar structural moieties of related . Clearly, this approach ignores characteristics of the force field of each particular molecule. Indeed, this concept implies that all responsibility for possible shifts of frequencies and other spectral features of related molecules (to which the force constants are transferred) lies with changes in the inverse kinetic energy matrix. With scaling of quantum-mechanical force fields, the relative errors indroduced during quantum-mechanical calculations of force constants at a certain theoretical level are assumed to be approximately the same for quasi-equivalent coordinates in similar structural fragments of related molecules. This assumption imposes less stringent constraints than the assumption of trasferability of force constants in series of related
METHODS OF SCALING QUANTUM MECHANICAL MOLECULAR FORCE FIELDS
No full textA.G. Yagola, I.V. Kochikov, G.M. Kuramshina and Yu. A. Pentin. ``Inverse Problems of Vibrational Spectroscopy"". VSP, Utrecht. The Netherlands, 1999, Chapter 11, p. 259. Yu, N. Panchenko, J. Mol. Street. 410-411. 327 (1997).Author Institution: Laboratory of Molecular Spectroscopy, Division of Physical Chemistry, Department of Chemistry, M.V. Lomonosov Moscow State UniversityA comparative analysis of various methods of empirical scaling of the quantum mechanical harmonic molecular force fields has been performed. The Pulay method of scaling is stressed to be applicable most successfully in the case where the quantum mechanical force field is determined close to the Hartree-Fock limit. This makes it possible to carry out correction of this force field with maximal retention of the peculiarities inherent in the the molecule under investigation. The solution of the inverse vibrational problem using quantum mechanical force field as a starting one may be considered to be the limiting case of scaling with maximum number of scale factors. Such approach corresponds to the traditional philosophy that searching force field should be closest to the starting . On the contrary, the main physical criterion used in the Pulay scaling procedure is closeness of the vibrational modes determined from the scaled force field to the vibrational modes obtained from the starting quantum mechanical force
TRANSFERABILITY OF PULAY'S SCALE FACTORS IN THE IVa GROUP OF THE MENDELEYEV PERIODIC SYSTEM
No full text P.C. Hariharan and J.A. Pople, Chem. Phys. Lett. 16, 217 (1972). Yu. N. Pancbenko, P. Pulay and F. T\""{o}r\""{o}k, J. Mol. Structure 34, 283 (1976); V.I. Pupyshev, Yu. N. Panchenko, Ch. W. Bock and G. Pongor, J. Chem. Phys. 94, 1247 (1991); Yu. N. Panchenko, G.R. De Mar\'{e} and V.I. Pupyshev, J. Phys. Chem. 99, 17544 (1995); Yu. N. Panchenko, Moscow Univ. Chem. Bull. 51 (5), 23 (1996).Author Institution: Laboratory of Molecular Spectroscopy, Division of Physical Chemistry, Department of Chemistry, M.V. Lomonosov Moscow State University; Laboratoire de Chimie Physique Mol\'{e}culaire, Facult\'{e} des Sciences, CP 160/09, Universit\'{e} Libre de Bruxelles; Laboratory of Molecular Structure and Quantum Mechanics, Division of Physical Chemistry, Department of Chemistry, M.V. Lomonosov Moscow State University, Moscow 119899, Russian Federation.Ab initio quantum mechanical calculations were performed for structures and force fields of 3,3-dimethylbutene-1, cyclopropene, 1-methylcyclopropene, and 1-trimethylsilyl-, 1,2-bis(trimethylsilyl)-, 1-trimethylgermyl-, 1,2-bis(trimethylgermyl)-, 1-trimethylstannyl-, and 1,2-bis(trimethylstannyl)-3,3-dimethylcyclopropene. Scale factors for correction of the quantum mechanical force fields of cyclopropene, 1-methylcyclopropene, and 3,3-dimethylbutene-1 were determined using Pulay's scaling Only the experimental vibrational frequencies of the light isotopomers of these molecules were used in the scaling procedure. The set of scale factors obtained was transferred to the quantum mechanical force fields of all the other molecules mentioned above. The vibrational problems for these molecules were solved. Complete vibrational analyses were carried out for the whole set of these related compounds. Transferability of scale factors for series of related compounds of cyclopropene with heteroatoms from the IVa group of the Mendeleyev Periodic System of chemical elements was demonstrated
Co-assignment of the molecular vibrational frequencies in different electronic states
No full textUltrafast electron diffraction experimental data for the structural parameters of molecules in excited electronic states are comparatively uncommon, hence these parameters are largely unknown. However, because differences between the molecular geometries of excited and ground electronic states cause differences in their experimental vibrational spectra it is important to establish a correspondence between the molecular vibrational frequencies in the ground state and those of the excited state of interest. The correct co-assignment of the experimental vibrational frequencies between two different electronic states of a molecule may be determined by the analog of the Duschinsky matrix\footnote{F.~Duschinsky, Acta Physicochim. URSS, 7(4), 551--566 (1937).} . This matrix is defined as where and are the matrices of the vibrational modes of the two states of the molecule under investigation. They are obtained by solving the vibrational problems in the I and II electronic states, respectively. Choosing the dominant elements in columns of the matrix and permuting these columns to arrange these elements along the diagonal of the transformed matrix makes it possible to establish the correct co-assignment of the calculated frequencies in the two electronic states. The rows of are for the vibrations in the I electronic state, whereas the columns are for vibrations in the II electronic state. The results obtained may be tested by analogous calculations of for isotopologues. The feasibility of co-assignments of the vibrational frequencies in the ground and T and S excited electronic states are demonstrated for {\em trans}-\footnote{Yu.~N.~Panchenko, Vibrational spectroscopy, 68, 236--240 (2013).}. The analogs of the Duschinsky matrix were used to juxtapose the vibrational frequencies of this molecule calculated at the CASPT2/cc-pVTZ level in the S, T and S states.Made available in DSpace on 2017-01-26T21:39:15Z (GMT). No. of bitstreams: 3
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Previous issue date: 2016-06-2
"Re-creating" Tadeusz Konwicki’s fiction : "Little apocalypse" and Yurii Andrukhovych’s "Moscoviad"a
No full textOn the basis of a comparative analysis of the worlds presented in Moscoviada by Yurii Andrukhovych and in the Little Apocalypse by Tadeusz Konwicki the article demonstrates the meaning of "metaphorical translation". Using the category proposed by Joseph Brodsky, the author of the article shows how similar characters, who search for their identities, are presented in both books
Growth of nanoparticles in liquid medium using magnetron sputtering technique
No full textTitle: Growth of nanoparticles in liquid medium using magnetron sputtering technique Author: Josef Kučera Department: Department of Surface and Plasma Science Supervisor: Mgr. Yurii Yakovlev, Ph.D., Department of Surface and Plasma Science Abstract: This thesis investigates the preparation of platinum and platinum-ruthenium alloy nanoparticles using magnetron sputtering method on a liquid substrate. Polypropylene glycol with three different molecular weights of 425, 1000, and 4000 was chosen as the liquid substrate. The influence of the different viscosities of these substrates on the size and morphology of the nanoparticles produced in the magnetron was investigated. Dynamic light scattering and transmission electron microscopy methods were used to determine the size of the nanoparticles. Furthermore, the catalytic activity of the produced nanoparticles in an alkaline environment was investigated using the rotating disk electrode technique. Keywords: Nanoparticles, Magnetron Sputtering, Polypropylene glycol, Hydrogen Fuel Cells, Water Electrolyzers, Hydrogen oxidation/reduction reactions
Vibrational spectra and ab initio analysis of tert-butyl, trimethylsilyl, trimethylgermyl, trimethylstannyl and trimethylplumbyl derivatives of 3,3-dimethylcyclopropene. XII. 1,2-Di-tert-butyl-3,3-dimethylcyclopropene
No full textThe synthesis of 1,2-di-tert-butyl-3,3-dimethylcyclopropene (I) is performed and its IR and Raman spectra are measured. Optimized geometries of I are obtained at the HF/6-31G* and CCSD/cc-pVDZ levels. The ab initio calculated spectra are used for the assignments of the experimental spectral data. The results obtained are compared with the corresponding data for 3,3-dimethylbut-1-ene and 3,3-dimethylcyclopropene. These experimental data and the total vibrational analysis of I supplement the information obtained in the series of investigations of tert-butyl, trimethylsilyl, trimethylgermyl, trimethylstannyl, and trimethylplumbyl derivatives of 3,3-dimethylcyclopropene. © 2009 Elsevier B.V. All rights reserved.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
George Yurii Shevelov as a master of academic writing
No full textУкраїнськомовні лінгвістичні праці Юрія Шевельова свідчать про нього як про яскраву авторську індивідуальність. У статті проаналізовано стильові та художні засоби, якими він послуговується, щоб дієвіше впливати на читачів. Зроблено висновок про актуальність його мовної практики для вдосконалення й уточнення сучасних норм українського наукового стилю.Ukrainian linguistic papers by George Yurii Shevelov are evidence of his outstanding author individuality. The article deals with analysis of some stylistic and expressive means, which he uses for more effective influence upon his readers. The conclusion of the study reveals that his language practice is topical for development and improvement of modern standards of Ukrainian academic discourse
George Yurii Shevelov as a master of academic writing
No full textУкраїнськомовні лінгвістичні праці Юрія Шевельова свідчать про нього як про яскраву авторську індивідуальність. У статті проаналізовано стильові та художні засоби, якими він послуговується, щоб дієвіше впливати на читачів. Зроблено висновок про актуальність його мовної практики для вдосконалення й уточнення сучасних норм українського наукового стилю.Ukrainian linguistic papers by George Yurii Shevelov are evidence of his outstanding author individuality. The article deals with analysis of some stylistic and expressive means, which he uses for more effective influence upon his readers. The conclusion of the study reveals that his language practice is topical for development and improvement of modern standards of Ukrainian academic discourse
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