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Excited states in 38,40,42 Si nuclei have been studied via in-beam γ-ray spectroscopy with multinucleon removal reactions. Intense radioactive beams of 40 S and 44 S provided at the new facility of the RIKEN Radioactive Isotope Beam Factory enabled γ-γ coincidence measurements. A prominent γ line observed with an energy of 742 (8) 23.20.Lv, 27.40.+z, 29.38.Db Shell closures and collectivity are important properties that characterize the atomic nucleus. Interchange of their dominance along isotopic or isotonic chains has attracted much attention. The recent extension of the research frontier to nuclei far away from the valley of stability has revealed several new phenomena for neutronor proton-number dependent nuclear structure. For example, a weakening or even disappearance of shell closures occur in several neutron-rich nuclei at N = 8 [1][2][3] and N = 20 [4][5][6]. A well known example in the case of N = 20 is the so-called 'island of inversion ' [7] located around the neutron-rich nucleus 32 Mg. The low excitation energy of the first 2 + state E x (2 + 1 ) and large E2 transition probability [4][5][6] clearly indicate shell quenching in 32 Mg despite the fact that N = 20 is traditionally a magic number. The next magic number, N = 28, which appears due to the f 7/2 -f 5/2 spin-orbit splitting, has also been explored [8][9][10][11][12][13]. Weakening of the shell closure is seen by the decrease of the 2 With proton number Z = 14 and neutron number N = 28, the nuclear structure of 42 Si is of special interest. A simple but important question that arises is whether the weakening of the N = 28 shell closure continues, causing an enhancement of nuclear collectivity, or if shell stability is restored owing to a possible doubly magic structure. A study on 42 Si was made by a two-proton removal reaction experiment with radioactive 44 S beams at the NSCL [15]. The small two-proton removal cross sec-

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The potential energy curve and the electron density distribution for low-lying electronic states of the helium and lithium atoms confined by an anisotropic harmonic oscillator potential have been studied for different confinement parameters (ωx, ωy, ωz) by using the quantum chemical configuration interaction (CI) method employing a Cartesian anisotropic Gaussian basis set supplemented by a quantum chemical standard Cartesian Gaussian basis set, respectively. In the case of the helium atom full CI wavefunctions have been used, and in the case of the lithium atom multi-reference CI wavefunctions have been employed. The results for the two confined quantum systems are compared to each other: parabolic-and non-parabolic-type potential energy curves are observed for states of both atoms in different type harmonic oscillator confinement. The non-parabolic potentials always appear in pairs, one with a double minimum and the other with a sharp edge at the minimum. They result from the interaction of energetically nearby states of the same symmetry. The electron density distributions of the states of the two atoms show deformation from spherical symmetry according to the symmetry and strength of the confining potential at the position of the atoms. The electron distribution of the states having non-parabolic potential energy curves is strongly deformed and occasionally shows curvilinear nodal planes of parabolic shape.

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