Elena Sheka - Academia.edu (original) (raw)
Papers by Elena Sheka
Molecular Crystals and Liquid Crystals
1999 9th International Crimean Microwave Conference 'Microwave and Telecommunication Technology'. Conference Proceedings (IEEE Cat. No.99EX363), 1999
ABSTRACT When discussing bare surfaces of silicon crystal, the concept of dangling bonds is widel... more ABSTRACT When discussing bare surfaces of silicon crystal, the concept of dangling bonds is widely used. The surface reconstruction is usually explained in terms of a tendency of the bonds to be saturated. However, the current microscopic calculations show that the availability of dangling bonds on the topmost silicon atoms is controversial enough
Molecular Crystals and Liquid Crystals, 1975
ABSTRACT
2013 23rd International Crimean Conference Microwave Telecommunication Technology, 2013
Graphene material science only slightly depends on the uniqueness of a regular one-atom- thick pl... more Graphene material science only slightly depends on the uniqueness of a regular one-atom- thick planar sheet while is mainly governed by peculiarities of electronic structure of `sp2-bonded carbon atoms that are densely packed in a honeycomb crystal'.
Molecular Crystals and Liquid Crystals, 1977
ABSTRACT
Journal of Experimental and Theoretical Physics
Molecular Crystals and Liquid Crystals, 1978
ABSTRACT
Molecular Crystals and Liquid Crystals, 1984
ABSTRACT A method is suggested for the calculation of the complete phonon spectrum of a polyatomi... more ABSTRACT A method is suggested for the calculation of the complete phonon spectrum of a polyatomic molecular crystal in the entire Brillouin zone. The spectrum includes both external and internal phonons and the method involves breaking up the high order dynamical matrix into several blocks covering large groups of phonons revealing marked intermode mixing inside a group and neghgible mixing among the modes of the neighbouring groups. The phonon mode structure is assigned through the analysis of the eigenvector matrix. The calculations using the suggested method are controlled by the calculation of all 144 frequencies at the point q = 0. The dispersion curves and the density of states of the entire 144-mode phonon spectrum of anthracene-d 0 crystal are presented.
Molecular Crystals and Liquid Crystals, 1977
... Phys. 30, No. 6, 1677-1684 (1975) (Eng) (PA 79: 21276). Benassi, R., Lazzeretti, P., and Tadd... more ... Phys. 30, No. 6, 1677-1684 (1975) (Eng) (PA 79: 21276). Benassi, R., Lazzeretti, P., and Taddei, F., Magnetic criteria for aromaticity, J. Phys. Chem. 79, No. 8, 848-851 (1975) (Eng) (PA. 78: 71910). Benson, SW and Luria, M., Electrostatics and the chemical bond. ...
This work is devoted to the consruction of the quantum field model, allowing, in particular, to d... more This work is devoted to the consruction of the quantum field model, allowing, in particular, to describe ferromagnetic properties in graphen structures adequately to the results of physical and numerical experiments. The offerd model describes properties of monoatom graphen layers (forming two-dimensional surfaces), which are connected with presence of nontrivial function of distribution of the spin density, formed as a result of spontaneous breakdown of the spin symmetry of valent electrons in atoms of carbon. Within the limits of the offered model possible exact solutions for field function of the spin density, explaning, in particular, experimentally observed ferromagnetic properties of graphen films are specified. Quantitative estimations of a thickness of the domain wall, dividing areas with counterdirected vectors of magnetization were suggested, which allows to check up offered theoretical model experimentally.
Molecular Crystals and Liquid Crystals Incorporating Nonlinear Optics, 1989
Nanostructured Materials, 1995
Abs&act-A problem of computer modelling of real nanomatetials is considewd. An algorithmic approa... more Abs&act-A problem of computer modelling of real nanomatetials is considewd. An algorithmic approach based on nanomaterial classification and particular properties of every classtftcation mode, including recently observed technological polymorphism, is suggested. The concept is put in plvzctice using the DYQ UAMOD progvam system, based on semi-empirical quantum-chemical methods, which allows the study of stncctuw and vibmtional spectra of nano-sized objects. The computing facilities aw demonstrated by a few examples concerning some technologically important materials.
Reaction Kinetics & Catalysis Letters, 1993
ABSTRACT An algorithm for large cluster construction for quantum-chemical modeling of amorphous s... more ABSTRACT An algorithm for large cluster construction for quantum-chemical modeling of amorphous silica structures is suggested. The algorithm is based on the conception that different species of disperse amorphous silica, namely aerosil, silica gel and aerogel are different polymorphic forms; that these polymorphic modifications can be classified by Libau's crystallochemical classification of silicates; that each classification mode is determined by the manufacturing method. The structure models presented are obtained in accordance with the algorithm and are in line with the chemical reactions forming the basis of commercial manufacturing of the products.
Soviet Physics Uspekhi, 1972
physica status solidi (b), 1976
Physica B: Condensed Matter, 1991
This paper presents a review of the latest results on the computational neutron/vibrational spect... more This paper presents a review of the latest results on the computational neutron/vibrational spectroscopy of dispersed catalysts such as ultrafine Ni particles, highly dispersed silica (aerosil and silica gel) and silicon nitride. The concept implies both a computer experiment and a real experiment.
Molecular Crystals and Liquid Crystals
1999 9th International Crimean Microwave Conference 'Microwave and Telecommunication Technology'. Conference Proceedings (IEEE Cat. No.99EX363), 1999
ABSTRACT When discussing bare surfaces of silicon crystal, the concept of dangling bonds is widel... more ABSTRACT When discussing bare surfaces of silicon crystal, the concept of dangling bonds is widely used. The surface reconstruction is usually explained in terms of a tendency of the bonds to be saturated. However, the current microscopic calculations show that the availability of dangling bonds on the topmost silicon atoms is controversial enough
Molecular Crystals and Liquid Crystals, 1975
ABSTRACT
2013 23rd International Crimean Conference Microwave Telecommunication Technology, 2013
Graphene material science only slightly depends on the uniqueness of a regular one-atom- thick pl... more Graphene material science only slightly depends on the uniqueness of a regular one-atom- thick planar sheet while is mainly governed by peculiarities of electronic structure of `sp2-bonded carbon atoms that are densely packed in a honeycomb crystal'.
Molecular Crystals and Liquid Crystals, 1977
ABSTRACT
Journal of Experimental and Theoretical Physics
Molecular Crystals and Liquid Crystals, 1978
ABSTRACT
Molecular Crystals and Liquid Crystals, 1984
ABSTRACT A method is suggested for the calculation of the complete phonon spectrum of a polyatomi... more ABSTRACT A method is suggested for the calculation of the complete phonon spectrum of a polyatomic molecular crystal in the entire Brillouin zone. The spectrum includes both external and internal phonons and the method involves breaking up the high order dynamical matrix into several blocks covering large groups of phonons revealing marked intermode mixing inside a group and neghgible mixing among the modes of the neighbouring groups. The phonon mode structure is assigned through the analysis of the eigenvector matrix. The calculations using the suggested method are controlled by the calculation of all 144 frequencies at the point q = 0. The dispersion curves and the density of states of the entire 144-mode phonon spectrum of anthracene-d 0 crystal are presented.
Molecular Crystals and Liquid Crystals, 1977
... Phys. 30, No. 6, 1677-1684 (1975) (Eng) (PA 79: 21276). Benassi, R., Lazzeretti, P., and Tadd... more ... Phys. 30, No. 6, 1677-1684 (1975) (Eng) (PA 79: 21276). Benassi, R., Lazzeretti, P., and Taddei, F., Magnetic criteria for aromaticity, J. Phys. Chem. 79, No. 8, 848-851 (1975) (Eng) (PA. 78: 71910). Benson, SW and Luria, M., Electrostatics and the chemical bond. ...
This work is devoted to the consruction of the quantum field model, allowing, in particular, to d... more This work is devoted to the consruction of the quantum field model, allowing, in particular, to describe ferromagnetic properties in graphen structures adequately to the results of physical and numerical experiments. The offerd model describes properties of monoatom graphen layers (forming two-dimensional surfaces), which are connected with presence of nontrivial function of distribution of the spin density, formed as a result of spontaneous breakdown of the spin symmetry of valent electrons in atoms of carbon. Within the limits of the offered model possible exact solutions for field function of the spin density, explaning, in particular, experimentally observed ferromagnetic properties of graphen films are specified. Quantitative estimations of a thickness of the domain wall, dividing areas with counterdirected vectors of magnetization were suggested, which allows to check up offered theoretical model experimentally.
Molecular Crystals and Liquid Crystals Incorporating Nonlinear Optics, 1989
Nanostructured Materials, 1995
Abs&act-A problem of computer modelling of real nanomatetials is considewd. An algorithmic approa... more Abs&act-A problem of computer modelling of real nanomatetials is considewd. An algorithmic approach based on nanomaterial classification and particular properties of every classtftcation mode, including recently observed technological polymorphism, is suggested. The concept is put in plvzctice using the DYQ UAMOD progvam system, based on semi-empirical quantum-chemical methods, which allows the study of stncctuw and vibmtional spectra of nano-sized objects. The computing facilities aw demonstrated by a few examples concerning some technologically important materials.
Reaction Kinetics & Catalysis Letters, 1993
ABSTRACT An algorithm for large cluster construction for quantum-chemical modeling of amorphous s... more ABSTRACT An algorithm for large cluster construction for quantum-chemical modeling of amorphous silica structures is suggested. The algorithm is based on the conception that different species of disperse amorphous silica, namely aerosil, silica gel and aerogel are different polymorphic forms; that these polymorphic modifications can be classified by Libau's crystallochemical classification of silicates; that each classification mode is determined by the manufacturing method. The structure models presented are obtained in accordance with the algorithm and are in line with the chemical reactions forming the basis of commercial manufacturing of the products.
Soviet Physics Uspekhi, 1972
physica status solidi (b), 1976
Physica B: Condensed Matter, 1991
This paper presents a review of the latest results on the computational neutron/vibrational spect... more This paper presents a review of the latest results on the computational neutron/vibrational spectroscopy of dispersed catalysts such as ultrafine Ni particles, highly dispersed silica (aerosil and silica gel) and silicon nitride. The concept implies both a computer experiment and a real experiment.