Ш 39 Шеин, И. Р. Зонная структура нового 16-18 K сверхпроводника LiFeAs в сравнении с Li0.5FeAs и LiCoAs [] / И. Р. Шеин, А. Л. Ивановский // Письма в Журнал экспериментальной и теоретической физики. - 2008. - Т. 88, N 5. - С. 377-381 : рис., табл., граф. - Библиогр.: (24 назв.) . - ISSN 0370-274X Рубрики: ХИМИЧЕСКИЕ НАУКИ Аннотация: На основе первопринципных FLAPW-CGA расчетов изучена зонная структура нового 16-18 К сверхпроводника LiFeAs как возможного первого представителя третьей ( так называемой "111") группы фаз, наряду с группами четырехкомпонентных "1111" оксиарсенидов LnOFeAs и трехкомпонентных "122" арсенидов AFe2As2, входящими в семейство новых высокотемпературных 26-56 К FeAs - сверхпроводников. Для LiFeAs обсуждены структура, энергетические зоны, плотности состояний, поверхность Ферми, коэффициенты низкотемпературной электронной теплоемкости и молярной парамагнитной восприимчивости Паули, которые сопоставлены с аналогичными данными для систем, моделирующих дырочное (Li0.5FeAs) и электронное (LiCoAs) допирование LiFeAs. |
S 91 Suetin, D. V. Structural, elastic and electronic properties and formation energiesfor hexagonal (W0.5Al0.5)C in comparison with binary carbidesWC and Al4C3 from first-principles calculations / D. V. Suetin, I. R. Shein, A. L. Ivanovskii // Physica B. - 2008. - Vol. 403. - P. 2654-2661 : il. - Bibliogr. : p. 2660-2661 (41 ref.) Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): РАСЧЕТЫ ПЕРВОПРИНЦИПНЫЕ -- КАРБИДЫ -- W-Al-C -- СВОЙСТВА УПРУГИЕ -- СВОЙСТВА СТРУКТУРНЫЕ -- СВОЙСТВА ЭЛЕКТРОННЫЕ Аннотация: First principle calculations have been performed with the purpose to understand the peculiarities of the structural, elastic parameters and electronic properties and interatomic bonding for novel hexagonal carbide (W0.5Al0.5)C in comparison with binary phases WC and Al4C3. The geometries of all phases were optimized and their structural, elastic parameters and theoretical density were established. Besides, we have evaluated the formation energies (Eform) of W0.5Al0.5C for different possible preparation routes (namely for the reactions with the participation of simple substances (metallic W, Al and graphite, binary W or Al carbides and metallic Al and W, or binary W and Al carbides). The results show that the synthesis of the ternary carbide from simple substances is more favorable in comparison with the reactions with participation of W and Al carbides. Moreover, band structures, total and partial densities of states were obtained and analyzed systematically for (W0.5Al0.5)C, WC and Al4C3 phases in comparison with available theoretical and experimental data. The bonding picture in W0.5Al0.5C was described as a mixture of metallic, ionic and covalent contributions with the high anisotropy for the covalent W–C and Al–C bonds, where p–p like Al–C bonds become weaker than p–d like W–C bonds Полный текст |
S 91 Suetin, D. V. Electronic properties of the hexagonal tungsten monocarbide(h-WC) with 3d impurities from first-principles calculations / D. V. Suetin, I. R. Shein, A. L. Ivanovskii // Physica B. - 2009. - Vol. 404. - P. 1887-1891 : il. - Bibliogr. : p. 1891 (24 ref.) Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): КАРБИД ВОЛЬФРАМА -- РАСЧЕТЫ ПЕРВОПРИНЦИПНЫЕ -- СВОЙСТВА ЭЛЕКТРОННЫЕ -- СВОЙСТВА СТРУКТУРНЫЕ -- СВОЙСТВА МАГНИТНЫЕ Аннотация: First-principles FLAPW-GGA calculations have been performed to predict the structural, electronic, cohesive and magnetic properties for hexagonal tungsten monocarbide (h-WC) doped with all 3d metals.The optimized lattice parameters, density of states, cohesive and formation energies have been obtained and analyzed for ternary solid solutions with nominal compositions W0.875M0.125C (where M = Sc, Ti ...Ni, Cu). In addition, the magnetic properties of these solid solutions have been examined, and magnetization has been established for W0.875Co0.125C Полный текст |
S 53 Shein, I. R. Elastic properties and chemical bonding in ternary arsenide SrFe2As2 and quaternaryoxyarsenide LaFeAsO – Basic phases for new 38–55 K superconductors fromfirst principles / I. R. Shein, A. L. Ivanovskii // Physica C. - 2009. - Vol. 469. - P. 15-19 : il. - Bibliogr. : p. 18-19 (31 ref.) Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): РАСЧЕТЫ ПЕРВОПРИНЦИПНЫЕ -- СВЕРХПРОВОДНИКИ -- СВОЙСТВА УПРУГИЕ -- FeAs Аннотация: Here we report the first-principle FLAPW-GGA calculations of the elastic properties of two related layered phases, namely, the ternary arsenide SrFe2As2 and the quaternary oxyarsenide LaFeAsO – basic phases for the newly discovered "122" and "1111" 38–55 K superconductors. The independent elastic constants (Cij), bulk moduli, compressibility, and shear moduli are evaluated and discussed. The numerical estimates??of the elastic parameters of the polycrystalline SrFe2As2 and L\aFeAsO ceramics are performed??for the first time. Additionally, the peculiarities of chemical bonding in these phases are discussed |
S 53 Shein, I. R. Electronic properties of the novel 18-K superconducting Y2C3 ascompared with 4-K YC2 from first principles calculations / I. R. Shein, A. L. Ivanovskii // Solid State Communications. - 2004. - Vol. 131. - P. 223-227 : il. - Bibliogr. : p. 226-227 (18 ref.) Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): СВЕРХПРОВОДНИКИ -- РАСЧЕТЫ ПЕРВОПРИНЦИПНЫЕ -- КАРБИД ИТТРИЯ Аннотация: The electronic band structure and ground state properties of the recently discovered 18-K superconducting Y2C3 material Akimitsu et al., 2004) have been examined by the full-potential linear muffin-tin method–generalized gradient approximation method and compared with those of the 4-K superconductor YC2. The calculations show that the growth of TC for the yttrium sesquicarbide as compared with 4-K YC2 may be due to the electronic factor: the near-Fermi DOS for Y2C3 was found to be about 36.7% higher that for YC2. The Fermi level of the "ideal" Y2C3 is located near the local DOS minimum, and thesuperconductivity of Y2C3-based materials will be very sensitive to synthesis conditions (for example, pressure and annealing effects) and the presence of various impurities and lattice vacancies. Probably these factors may be used to vary the superconductivity of the Y2C3 phase over a wide range Полный текст |
I-60 Influence of Carbon Vacancies on the Electronic Properties of Solid Solutions in the W–Al–C System from First Principles Calculations / D. V. Suetin, I. R. Shein, V. G. Bamburov, A. L. Ivanovskii // Doklady Physical Chemistry. - 2009. - vol. 424, № 1. - P. 14-16 : il. - Bibliogr. : p. 16 (13 ref.) Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): ЭЛЕКТРОННЫЕ СВОЙСТВА -- РАСТВОРЫ ТВЕРДЫЕ -- РАСЧЕТЫ ПЕРВОПРИНЦИПНЫЕ -- КАРБИДЫ ПЕРЕХОДНЫХ МЕТАЛЛОВ \\\\Expert2\\nbo\\Doklady Physical Chemistry\\2009, V. 424, N 1, p.14-16.pdf |