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Öğe MCDHF and RCI calculations of energy levels, lifetimes, and transition rates in Si III and Si IV(Edp Sciences S A, 2019) Atalay, B.; Brage, T.; Jonsson, P.; Hartman, H.We present extensive multiconfiguration Dirac-Hartree-Fock and relativistic configuration interaction calculations including 106 states in doubly ionized silicon (Si III) and 45 states in triply ionized silicon (Si IV), which are important for astrophysical determination of plasma properties in different objects. These calculations represents an important extension and improvement of earlier calculations especially for Si III. The calculations are in good agreement with available experiments for excitation energies, transition properties, and lifetimes. Important deviations from the NIST-database for a selection of perturbed Rydberg series are discussed in detail.Öğe Multiconfiguration Dirac-Hartree-Fock calculations of Lande g-factors for ions of astrophysical interest: B II, C I-IV, Al I-II, Si I-IV, P II, S II, Cl III, Ar IV, Ca I, Ti II, Zr III, and Sn II(Edp Sciences S A, 2020) Li, W.; Rynkun, P.; Radziute, L.; Gaigalas, G.; Atalay, B.; Papoulia, A.; Wang, K.Aims. The Lande g-factor is an important parameter in astrophysical spectropolarimetry, used to characterize the response of a line to a given value of the magnetic field. The purpose of this paper is to present accurate Lande g-factors for states in B II, C I-IV, Al I-II, Si I-IV, P II, S II, Cl III, Ar IV, Ca I, Ti II, Zr III, and Sn II.Methods. The multiconfiguration Dirac-Hartree-Fock and relativistic configuration interaction methods, which are implemented in the general-purpose relativistic atomic structure package GRASP2K, are employed in the present work to compute the Lande g-factors for states in B II, C I-IV, Al I-II, Si I-IV, P II, S II, Cl III, Ar IV, Ca I, Ti II, Zr III, and Sn II. The accuracy of the wave functions for the states, and thus the accuracy of the resulting Lande g-factors, is evaluated by comparing the computed excitation energies and energy separations with the National Institute of Standards and Technology (NIST) recommended data.Results. All excitation energies are in very good agreement with the NIST values except for Ti II, which has an average difference of 1.06%. The average uncertainty of the energy separations is well below 1% except for the even states of Al I; odd states of Si I, Ca I, Ti II, Zr III; and even states of Sn II for which the relative differences range between 1% and 2%. Comparisons of the computed Lande g-factors are made with available NIST data and experimental values. Analysing the LS-composition of the wave functions, we quantify the departures from LS-coupling and summarize the states for which there is a difference of more than 10% between the computed Lande g-factor and the Lande g-factor in pure LS-coupling. Finally, we compare the computed Lande g-factors with values from the Kurucz database.Öğe Radiative Lifetimes for Singly Ionized Beryllium(Polish Acad Sciences Inst Physics, 2016) Celik, G.; Atalay, B.; Ates, S.The theoretical lifetimes for singly ionized beryllium (Be II) have been calculated using the weakest bound electron potential model theory and the quantum defect orbital theory under the assumption of the LS coupling scheme. In the calculations, many states are considered. Some lifetime values for highly excited levels have been obtained using these methods. The lifetimes presented in this work have been compared with the early theoretical calculations and measurements presented in the literature. A good agreement with the results in the literature has been obtained.Öğe Simulation of Ni-like and Co-like X-rays emitted from laser produced tin plasmas(Inst Physics Acad Sci Czech Republic, 2006) Atalay, B.; Aydin, R.; Demir, A.; Kenar, N.; Kacar, E.The Ni-like and Co-like X-rays emitted from laser produced Tin plasmas generated using the 1.06 mu m, 1.2 ns pulses from a Nd-YAG laser were modelled. The modelling includes the Ni-like and Co-like X-ray resonance line spectrum emitted from Sn plasma between 12 angstrom - 25 angstrom and also free-free and free-bound continuous spectrum emitted from the Zn-, Cu-, Ni-, Co- and Fe-like ions between 1 angstrom and 30 angstrom. Then, X-ray conversion efficiencies were calculated using these spectra. Maximum X-ray conversion efficiency was obtained 3.54 % at power density of 5 x 10(12) Wcm(-2) into 2 pi steradian. X-ray pulse durations were calculated spectrally integrated total X-ray emission of the Ni-like and Co-like from Sn plasmas.Öğe Transition probabilities of neutral scandium(Canadian Science Publishing, Nrc Research Press, 2014) Ozturk, I. K.; Celik, G.; Gokce, Y.; Atalay, B.; Guzelcimen, F.; Er, A.; Basar, G.The electric dipole transition probabilities and the oscillator strengths of neutral scandium have been calculated using the quantum defect orbital theory and the Cowan code for the 3d4s(2)-3d4s4p, 3d(2)4s-3d(2)4p, and 3d4s(2)-4s(2)4p transitions. In addition, a parametric analysis of the fine structure for the 3d4s(2) configuration of even parity is performed using Cowan code. The transition probabilities and the oscillator strengths obtained in this work are mostly in agreement with the data obtained from different theoretical works given in the literature. Moreover, transition probabilities for 24 levels of neutral scandium are given for the first time.
