The isovector giant dipole resonances (IVGDR) in proton-rich Ar and Ca isotopes have been systematically investigated using the resonant continuum Hartree-Fock+BCS (HF+BCS) and quasiparticle random phase approximation (QRPA) methods. The Skyrme SLy5 and density-dependent contact pairing interactions are employed in the calculations. In addition to the giant dipole resonances at energy around 18 MeV, pygmy dipole resonances (PDR) are found to be located in the energy region below 12 MeV. The calculated energy-weighted moments of PDR in nuclei close to the proton drip-line exhaust about 4% of the TRK sum rule. The strengths decrease with increasing mass number in each isotopic chain. The transition densities of the PDR states show that motions of protons and neutrons are in phase in the interiors of nuclei, while the protons give the main contribution at the surface. By analyzing the QRPA amplitudes of proton and neutron 2-quasiparticle configurations for a given low-lying state, we find that only a few proton configurations give significant contributions. They contribute about 95% to the total QRPA amplitudes, which indicates that the collectivity of PDR states is not strong in proton-rich nuclei in the present study.

已使用共振连续谱 Hartree-Fock+BCS (HF+BCS) 和准粒子随机相位近似 (QRPA) 方法系统地研究了富含质子的 Ar 和 Ca 同位素中的等向量巨偶极共振 (IVGDR)。计算中采用了 Skyrme SLy5 和依赖于密度的接触配对相互作用。除了能量在 18 MeV 左右的巨大偶极共振外，侏儒偶极共振 (PDR) 被发现位于 12 MeV 以下的能量区域。在靠近质子滴线的原子核中计算的 PDR 的能量加权矩约为 TRK 和规则的 4%。强度随着每个同位素链中质量数的增加而降低。PDR 态的跃迁密度表明质子和中子的运动在原子核内部是同相的，而质子在表面提供主要贡献。通过分析给定低位态的质子和中子 2-准粒子配置的 QRPA 振幅，我们发现只有少数质子配置有显着贡献。它们对总 QRPA 振幅的贡献率约为 95%，这表明在本研究中富质子核中 PDR 状态的集体性不强。