Electronic Structure of AC-Clusters and High-Resolution Xray Spectra of Actinides in Solids
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Electronic Structure of AC-Clusters and High-Resolution Xray Spectra of Actinides in Solids Nicolay Alex Kulagin Physics, Kharkov National University for RAdioelectronics, Shakespeare, 6-48, Kharekov, 61045, Ukraine SUMMARY. Ab initio calculations using SCF approach for and analysis of results of investigation of the electronic structure of the clusters RA+n:[L]k with rare earths or actinides were carried out for the clusters in solids and liquids. Theoretical results for the electronic structure, radial integrals and energy of X ray lines are presented for AC ions with unoccupied 5f shell in the clusters in oxides, chlorides and fluorides environment. Possibility of collapse of nf shell for the separate clusters and identification of electronic state of ions with unstable nuclei, are discussed, too. PACS: 71.24; 31.15 A Key words: cluster, X ray fluorescence, actinide, rare earth INTRODUCTION Ions with unfilled nf- shell such as rare earths, RE and actinides, AC have been studied for a long time [1-4]. Magnetic, electrical, optical and other physical properties of solids contain RE and AC, depend on electronic state of the ions. The nfN- main configuration for the most ions and excited states, such as nfN(n+1)sN' or nfN(n+1)pN" are important when considering the scheme of the energy levels, the intensity of the optical spectra, magnetic and conducting properties of solids [4-6]. Theoretical study of the free ions, in general, based on full separation of variables approach and Hartree-Fock approximation in different modifications [1-2] and Fock-Dirac method [34]. Hartree-Fock-Pauli, HFP, method including the main relativistic parts of the Breit’s operator is more simple than Fock-Dirac one and widely used, too [6]. The results of HFP method are closely to Fock-Dirac data for the separate parameters of the electronic structure of high-weight ions. Moreover, HFP method quite correctly describes the optical and X ray spectra of free and doped RE and AC [4-6]. Correlation effects, which are considered by multi-configuration approximation [5-6] or parametrization schemes method by G. Racah [7] or K. Rajnak and B. Wybourne [7] are important for the ions and must be included to the calculation procedure [8]. It is well known that the electronic distribution of the ion changes during free ion-to-solid state transition. The electrons’ distribution of inner, and not only external shells, changes for an ion in a crystal or cluster. Chemical and valency shift of X ray lines relates to the redistribution of electronic density for inner region of ions, first of all [9-13]. Separate results for the chemical shift of RE and AC were presented in papers [14-15]. The book [6] and papers [9-12] contain the theoretical and experimental data for optical spectra and energy of separate K- and L- X ray lines for all RE and separate AC. For AC ions in opposite of RE the experimental results are very scanty [14-18]. Spectra of the free actinides with the 5fN7sN’ configurations are studied in [15]. And spectra of the doped actini
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