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The evolution of single-particle energies $\it E_{nlj}$ of near to spherical medium and medium- heavy nuclei as they approached neutron drip line was studied within the dispersive optical model (DOM) [1]. The main attention was paid on the dependence of the diffuseness parameter $\it a_{HF}$ of the Hartree-Fock component of the potential on neutron-proton asymmetry and its influence on the evolution. It was shown that the agreement with the available experimental data was improved if $\it a_{HF}$ depended on neutron-proton asymmetry:
$\it a_{HF}= \it a_{HF}^0\pm \it a_{HF}^1(N-Z)/A$, + for n, – for p . (1)
In other words, the diffuseness $\it a_{HF}$ increased when the Fermi energy goes up. The dependence (1) differs from that of the global diffuseness parameter $\it a_V^{KD}$ of the traditional optical model potential [2]. The parameter $a_V^{KD}$ decreases with increasing mass number A of the nucleus for both neutrons and protons. The dependence (1) leads, in particular, to the following: more pronounced inversion of the $2\it s_{1/2}–1\it d_{3/2}$ proton levels in stable Са isotopes and the $1\it g_{7/2}–2\it d_{5/2}$ proton levels in stable Sn isotopes; more pronounced evolution of the energy gap between the neutron states $1\it f_{5/2}$ and $2\it p$ in the stable $1\it f-2\it p$– shell nuclei; better agreement with the experimental energies $\it E_{nlj}$ of the $1\it d_{3/2}$ neutron state in neutron-rich Si isotopes [3] comparing to the parameter $\it a_{HF} = \it a_V^{KD}$ (see fig). Thus, dependence (1) improves the predictive power of DOM with respect to the nuclei far from the $\beta$-stability valley.
- C.Mahaux, R.Sartor . Adv. Nucl. Phys. 1991. V. 20, P. 1.
- A.J.Koning, J.P.Delaroche Nucl. Phys. A. 2003. V. 713. P. 231.
- O.V.Bespalova, N.A.Fedorov, A.A.Klimochkina et al. Eur. Phys. J. A. 2018. 54: 2.
