Browsing by Author "W.A. Yahya"

Now showing 1 - 8 of 8
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    Ab Initio Study of the Physical Properties of Cs-Based Double Perovskites Cs2 AX6 (A = Ge, Mn; X = Cl, I)
    (2024-04-15) A.A. Yahaya; W.A. Yahya; A.S. Ahmed; A.A. Sholagberu
    Device applications in magnetic media, spintronics, oxygen membranes, sensors, etc., are some of the uses of ferrite materials. In this work, we have studied the structural, electronic, magnetic, mechanical, and thermoelectric properties of Cs-based double perovskites Cs2 AX6 (A = Ge, Mn; X = Cl, I), using Quantum Espresso with generalized gradient approximation Perdew–Burke–Ernzerhof and Perdew– Burke–Ernzerhof in solids exchange–correlation functionals. The band structure results show that Cs2 GeCl6 and Cs2 MnCl6 are semiconductors with direct band gaps. However, there are bands crossing observed for Cs2 GeI6 from the conduction band minimum to the valence band maximum, indicating the metallic nature of the material. Moreover, Cs2 MnI6 has magnetic properties; it exhibits a metal- lic nature in the spin-up state and a semiconductor nature in the spin-down state, suggesting that it can be used in spintronics applications. The calculated total magnetic moment of Cs2 MnCl6 is 3.0µB (for both Perdew–Burke–Ernzerhof and Perdew–Burke–Ernzerhof in solids), while for Cs2 MnI6 , the calculated total magnetic moments are 3.02µB and 3.06µB , for Perdew–Burke–Ernzerhof and Perdew– Burke–Ernzerhof in solids exchange–correlation functionals, respectively. The results of the mechanical properties calculations show that Cs-based double perovskites Cs2 AX6 (A = Ge, Mn; X = Cl, I) are mechanically stable. Cauchy’s pressure and Poisson’s, Frantsevich’s, and Pugh’s ratios of the studied materials confirm that Cs2 MnCl6 is brittle, while the remaining studied double perovskite materials are ductile. Electrical conductivity, thermal conductivity, Seebeck coefficients, power factor, and figure of merit are the thermoelectric parameters analyzed in this study. Seebeck coefficients, electrical con- ductivity, and power factor increase with the rise in temperature, and Cs2 MnX6 (X = Cl, I) double perovskite materials have higher values of electrical conductivity than Cs2 GeX6 (X = Cl, I). All the studied materials have positive type conductivity due to their positive Seebeck coefficient values.
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    Half-lives of α-decay from nuclei with Z = 92 − 118 using the double folding model with relativistic NN interactions
    (2022-06-21) W.A. Yahya; I.D. Olusola; A.A. Saeed; O.K. Azeez
    The α-decay half-lives of nuclei with Z = 92 − 118 have been calculated using the WKB semi-classical approximation. The α-daughter nuclear interaction potentials are obtained from the double folding model, where the effective nucleon-nucleon (NN) interactions are obtained from relativistic mean field theory La- grangian (R3Y). In addition to using R3Y NN interactions containing only linear σ , ω, and ρ mesons (R3Y-HS), R3Y parametrizations containing non-linear terms (NL2 and NL-SH) are also employed. In fact, they are found to give better descriptions of the α-decay half-lives than R3Y-HS. Moreover, two em- pirical formulas are employed in the study. They have been included to further test the accuracy of the R3Y models.
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    Nonrelativistic and relativistic bound state solutions of the molecular Tietz potential via the improved asymptotic iteration method
    (2014-04-14) W.A. Yahya; K. Issa; B.J. Falaye; K.J. Oyewumi
    We have obtained the approximate analytical solutions of the relativistic and nonrelativistic molecular Tietz potential using the improved asymptotic iteration method. By approximating the centrifugal term through the Greene–Aldrich approximation scheme, we have obtained the energy eigenvalues and wave functions for all orbital quantum numbers [Formula: see text]. Where necessary, we made comparison with the result obtained previously in the literature. The relative closeness of the two results reveal the accuracy of the method presented in this study. We proceed further to obtain the rotational-vibrational energy spectrum for some diatomic molecules. These molecules are CO, HCl, H2, and LiH. We have also obtained the relativistic bound state solution of the Klein−Gordon equation with this potential. In the nonrelativistic limits, our result converges to that of the Schrödinger system.
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    Nonrelativistic and relativistic bound state solutions of the molecular Tietz potential via the improved asymptotic iteration method
    (2014) W.A. Yahya; K. Issa; B.J. Falaye; K.J. Oyewumi
    We have obtained the approximate analytical solutions of the relativistic and nonrelativistic molecular Tietz potential using the improved asymptotic iteration method. By approximating the centrifugal term through the Greene–Aldrich approximation scheme, we have obtained the energy eigenvalues and wave functions for all orbital quantum numbers [Formula: see text]. Where necessary, we made comparison with the result obtained previously in the literature. The relative closeness of the two results reveal the accuracy of the method presented in this study. We proceed further to obtain the rotational-vibrational energy spectrum for some diatomic molecules. These molecules are CO, HCl, H2, and LiH. We have also obtained the relativistic bound state solution of the Klein−Gordon equation with this potential. In the nonrelativistic limits, our result converges to that of the Schrödinger system.
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    Predictions of \(\alpha \)-decay Half-lives for Neutron-deficient Nuclei with the Aid of Artificial Neural Network
    (2022-03-13) A.A. Saeed; W.A. Yahya; O.K. Azeez
    In recent years, the artificial neural network (ANN) has been success- fully applied in nuclear physics and some other areas of physics. This study begins with the calculations of α-decay half-lives for some neutron- deficient nuclei using the Coulomb and proximity potential model (CPPM), temperature-dependent Coulomb and proximity potential model (CPPMT), Royer empirical formula, new Ren B (NRB) formula, and a trained artificial neural network model (T ANN ). By comparison with experimental values, the ANN model is found to give very good descriptions of the half-lives of the neutron-deficient nuclei. Moreover, CPPMT is found to perform bet- ter than CPPM, indicating the importance of employing the temperature- dependent nuclear potential. Furthermore, to predict the α-decay half-lives of unmeasured neutron-deficient nuclei, another ANN algorithm is trained to predict the Q α values. The results of the Q α predictions are compared with the Weizsäcker–Skyrme-4+RBF (WS4+RBF) formula. The half-lives of unmeasured neutron-deficient nuclei are then predicted using CPPM, CPPMT, Royer, NRB, and T ANN , with Q α values predicted by ANN as in- puts. This study concludes that half-lives of α-decay from neutron-deficient nuclei can successfully be predicted using ANN, and this can contribute to the determination of nuclei at the driplines.
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