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On the basis of the Hartree-Fock-Bogolyubov (HFB) method with various versions of Skyrme forces we investigated the position of the neutron drip-line (NDL) of Ca isotopes with allowance for axial deformation of nuclei. For calculations of the properties of the ground state of even-even isotopes of Ca, we used computer code HFBTHO v2.00d [1] and our software package as in [2]. Our calculations and those of various authors [3] have shown that the position of the NDL for different types of Skyrme forces differs significantly in the boundary value of the number of neutrons $N_{drip-line}$. We have shown that for the same type of Skyrme forces, the determination of the $N_{drip-line}$ is also ambiguous. We performed constrained HFB calculations of the total energy of Ca isotopes in the vicinity of the NDL depending on the quadrupole deformation parameter $\beta_2$ in the range of $-0.5\leq\beta_2\leq0.5$. It is shown that for the isotopes $^{68}$Ca (forces UNEDF1) and $^{66}$Ca (forces SLy4) over the entire range of considered $\beta_2$, in the vicinity of the min curve E($\beta_2$), the chemical potential of the nuclei is $\lambda_n<0$. These isotopes can be considered as neutron-stable. For the isotopes $^{70}$Ca (forces UNEDF1) and $^{68}$Ca (forces SLy4) in the vicinity of the min curve E($\beta_2$), the chemical potential of the nuclei is $\lambda_n>0$. If we consider the condition $\lambda_n<0$ as a condition for the stability of the nucleus with respect to the emission of one neutron, then the nucleus $^{70}$Ca (for forces UNEDF1) and $^{68}$Ca (for SLy4 forces) cannot be considered as neutron-stable. In [3], these nuclei are given as neutron-stable for which the separation energies of one neutron have positive values.
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