The structural, electronic, elastic and magnetic properties of cerium, praseodymium and their hydrides REH x（RE=Ce, Pr and x=2, 3） were investigated by the first principles calculations based on density functional t...The structural, electronic, elastic and magnetic properties of cerium, praseodymium and their hydrides REH x（RE=Ce, Pr and x=2, 3） were investigated by the first principles calculations based on density functional theory using the Vienna ab-initio simulation package. At zero pressure all the hydrides were stable in the ferromagnetic state. The calculated lattice parameters were in good agreement with the experimental results. The bulk modulus decreased with the increase in the hydrogen content for these hydrides. The electronic structure revealed that di-hydrides were metallic whereas trihydrides were half metallic at zero pressure. A pressure-induced structural phase transition from cubic to hexagonal phase was predicted in these hydrides. The computed elastic constants indicated that these hydrides were mechanically stable at zero pressure. The calculated Debye temperature values were in good agreement with experimental and other theoretical results. A half metallic to metallic transition was also observed in REH3 under high pressure. Ferromagnetism was quenched in these hydrides at high pressures.展开更多
The astrophysical S-factor of the ^(12)C(p,γ_(0))^(13)N reaction at energies from 25 keV to 5 MeV within the framework of a modified potential cluster model with forbidden states is considered.The experimental phase ...The astrophysical S-factor of the ^(12)C(p,γ_(0))^(13)N reaction at energies from 25 keV to 5 MeV within the framework of a modified potential cluster model with forbidden states is considered.The experimental phase shifts resonant δ_(2)_(S_(1/2)),δ_(2)_(S_(3/2)),and non-resonant δ_(2)_(D_(3/2)) at the energies up to E_(c.m.)=3 MeV are reproduced with high accuracy,which provides the appropriate agreement with the experimental data for the S-factor of 1950-2023 years.Two sets of asymptotic constant are used:Set I refers to C_(w)=1.30(2),and Set II refers to C_(w)=1.37(1).Set I leads to the astrophysical factor S(25)=1.34±0.02 keV-b,which is in agreement with data by Skowronski et al.,2023-1.34±0.09 keV-b;Set II gives S(25)=1.49±0.02 keV-b,which is in agreement with data by Kettner et al.,2023-1.48±0.09 keV-b.The reaction rates of ^(12)C(p,γ_(0))^(13)N at temperatures T_(9) from 0.001 to 10 are calculated.The detailed comparison with some models,the R-matrix approach,and NACRE II data for reaction rates is considered.展开更多
文摘The structural, electronic, elastic and magnetic properties of cerium, praseodymium and their hydrides REH x（RE=Ce, Pr and x=2, 3） were investigated by the first principles calculations based on density functional theory using the Vienna ab-initio simulation package. At zero pressure all the hydrides were stable in the ferromagnetic state. The calculated lattice parameters were in good agreement with the experimental results. The bulk modulus decreased with the increase in the hydrogen content for these hydrides. The electronic structure revealed that di-hydrides were metallic whereas trihydrides were half metallic at zero pressure. A pressure-induced structural phase transition from cubic to hexagonal phase was predicted in these hydrides. The computed elastic constants indicated that these hydrides were mechanically stable at zero pressure. The calculated Debye temperature values were in good agreement with experimental and other theoretical results. A half metallic to metallic transition was also observed in REH3 under high pressure. Ferromagnetism was quenched in these hydrides at high pressures.
基金Carried out within Project No.AP19676483«Study of hydrogen thermonuclear fusion processes in the CNO cycle in the Sun and in stars»,supported by the Ministry of Science and Higher Education of the Republic of Kazakhstan.
文摘The astrophysical S-factor of the ^(12)C(p,γ_(0))^(13)N reaction at energies from 25 keV to 5 MeV within the framework of a modified potential cluster model with forbidden states is considered.The experimental phase shifts resonant δ_(2)_(S_(1/2)),δ_(2)_(S_(3/2)),and non-resonant δ_(2)_(D_(3/2)) at the energies up to E_(c.m.)=3 MeV are reproduced with high accuracy,which provides the appropriate agreement with the experimental data for the S-factor of 1950-2023 years.Two sets of asymptotic constant are used:Set I refers to C_(w)=1.30(2),and Set II refers to C_(w)=1.37(1).Set I leads to the astrophysical factor S(25)=1.34±0.02 keV-b,which is in agreement with data by Skowronski et al.,2023-1.34±0.09 keV-b;Set II gives S(25)=1.49±0.02 keV-b,which is in agreement with data by Kettner et al.,2023-1.48±0.09 keV-b.The reaction rates of ^(12)C(p,γ_(0))^(13)N at temperatures T_(9) from 0.001 to 10 are calculated.The detailed comparison with some models,the R-matrix approach,and NACRE II data for reaction rates is considered.
