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A systematic study of Yb isotopes of even-even nuclei with neutron number N =60-130 has been done with axially deformed covariant density functional theory (CDFT) [1] using finite-range interaction DD-ME2 [2] and zero-range interaction DD-PC1 [3]. The shape coexistence and transitional nature of nuclei are found in the neighbourhood of magic nuclei through the potential energy curve. The potential energy curve is obtained by performing the constraint calculation on the axial mass quadrupole moment. The bubble structure is characterised by the reduction in the density at the centre of the nucleus (r=0). The reduction in the density at the centre is due to the vacancy in the s-orbital (l=0), and other non-zero l’s are suppressed at the centre and do not contribute. The reduction in density is estimated in terms of depletion fraction (DF). The DF is found to be decreasing with the quadrupole deformation in the s-orbital region of the chosen series, and beyond this, it is increasing with the quadrupole deformation. The symmetry energy is directly connected with the isospin asymmetry and is defined as the energy penalty in breaking the isospin asymmetry. The symmetry energy of finite nuclei is obtained with the coherent density fluctuation model (CDFM) [4]. The symmetry energy is found to be affected by the quadrupole deformation. The symmetry energy for the oblate shape is found to be higher than that of the spherical and prolate shapes, and it decreases with an increase in prolate deformation and isospin asymmetry. The symmetry energy is also found to be correlated with the depletion fraction when the effect of quadrupole deformation is absent. References. 1. T. Niksic, N. Paar, D. Vretenar, P. Ring, Computer Physics Communications 185 (6) (2014) 1808-1821. 2. G.A. Lalazissis, T. Niksic, D. Vretenar, P. Ring, Phys. Rev. C 71 (2005) 024312. 3. T. Niksic, D. Vretenar, P. Ring, Phys. Rev. C 78(3) (2008) 034318. 4. A.N. Antonov, V.A. Nikolaev, I.Z. Petkov, Zeitschrift fur Physik A Atomic and Nuclei 297 (3) (1980) 257-260.
