[en] A question of participation of inner 6p-atomic orbitals in the formation of chemical bond and expansion of valency possibilities of actinides at the expense of it is discussed. The forecasting of new valency forms for actinides puts a question of their possible similarity with lantanides. It is shown that the similarity is of a ''cross'' character, and it is explained by cymbate change of excitation energy from fsup(n) to fsup(n-1)d-electron states. In the first half of lanthanides 4f-electron levels are more stable than in the second one, whereas in actinides in the first half 5f-levels are less stable than in the second one. Such similarity will be manifested in all properties, which are conditioned by partial participation in the formation of bonds of d-atomic orbitals. In the limiting case of ion configurations of fsup(n) tetrade effect should be manifested, which is conditioned by the fact that quantum numbers of complete orbital momentum are symmetric as to electron configurations of f₃(f₁₀) and f₄(f₁₁). It will be manifested in all the properties, which are determined by the diffusion of f-orbitals

[en] Short note. 1 tab

[en] The band structure of metallic actinides from Am to Es is calculated by the LAPW method taking into account spin-orbit interaction and core relaxation. Densities of states, Fermi energies, densities of states at the Fermi level, and effective charges within MT-spheres are found for metals with face-centered-cubic (fcc) structures. The nature of the change of physicochemical properties along the series is discussed

[en] Calculations of zone structure of actinides from thorium to americium in FCC and BCC lattices were carried out by relativistic method with corrugated potential and with an account of skeleton state relaxation. Problems of f-state localization in metal americium are considered

[en] Study of band structures of actinides from thorium to americium in hcp and bcc lattices is carried out by LCPW relativistic method corrugated potential with an account of relaxation skeleton states, and values of state densities on the Fermi level are obtained. Disagreement with experimental data by coefficient of γ-specific electron heat capacity for plutonium and neptunium is identified. Explanation of this fact, based on f-state localization due to Condo effect in these elements is proposed

[en] Electronic structure of AnO₂⁺ cations for elements from uranium to californium is investigated using quasi-relativistic X_α-method of scattered waves. It is shown that due to localization of outer-shell 5f-electrons and inner-shell 6p-electrons on atomic actinide orbitals and electron density transfer from 6d-orbitals to oxygen atomic orbitals the bond strength is decreased by the end of the series. Higher 5f- and 6p- electron localization leads to a decrease of actinide-oxygen bond in AnO₂⁺ as compared to AnO₂²⁺

[en] The review and critical analysis of papers on quantum chemistry of f-elements are presented. The results of quantum-chemical calculations of actinide atoms, ions and molecules are given. Electronic structure and properties of oxygen and chloride complexes of actinides within the frames of the MO method are discussed. Problems of stability of f-elements valence forms, analogies between lanthanides and actinides are considered. Relativistic effects on lanthanide and actinide properties are analyzed. The mechanism of reactions of actinide compounds and geometry of their molecules are investigated. Quantum-chemical interpretation of isomeric shifts in actinide Moessbauer spectra is given. Peculiarities of electronic structure of f-elements are discussed

[en] The problems associated with characteristic features of actinide elements are considered, viz. spatial configuration of nuclei in actinyl ions, possible existence of actinyl ions with angular structure, a relationship between the stability of actinyl ions and their geometry. Within the model of maximum overlap, it is shown that if in the actinide ion Ansup(Z+) there are closely spaced d- or s-levels in the electron configuration of the ground state, the dioxycation AnO₂²⁺ formed will be stable in the linear coordination. The geometry of actinyl systems is considered within the framework of efficient hybridization and from the viewpoint of electron-oscillation interaction

[en] The nature of correlation between redox potentials of actinide elements and absorption band frequencies in electron spectra of their complexes has been studied within the framework of quantum-chemical concept. The parameters affecting the redox potential and the scheme of molecular levels for octahedral complexes have been analyzed, and the absorption bands in electron spectra have been assigned. The value determining correlation is shown to be the energy of excitation into the valent state

[en] Stabilities of curium compounds with higher oxidation degrees of curium (Cmsup((5)), Cmsup((6)), Cmsup((7))) have been theoretically compared. Using the correlation between the energies of fsup(n)→fsup(n-d) d-transitions of curium atoms in the corresponding charge states with oxidation potentials (Cmsup((4-5))fsup(6)→fsup(5)dsup(1); Cmsup((5-6))fsup(5)→fsup(4)dsup(1); Cmsup((6-7)) fsup(4)→fsup(3)dsup(1)) it is found that Cmsup((7)) is unstable (Esup(0)(6-7)=2.7V) and Cmsup((6)) is to exist in the solutions: Esup(0)(5-6)=1.5V. At the same time Esup(0)(4-5)=17V, i.e. Cmsup((6)) is more stable than Cmsup((5))