Yazar "Demir, Celalettin" seçeneğine göre listele

Listeleniyor 1 - 6 / 6
  • Küçük Resim
    Öğe
    Coulomb, exchange, kinetic, nuclear attraction and ionization energies of two-electron quantum dot with finite confinement potential
    (Elsevier B.V., 2023) Yakar, Yusuf; Çakır, Bekir; Demir, Celalettin; Özmen, Ayhan
    We have calculated Coulomb, exchange and configuration-average ionization energies for the ground and excited configurations in helium atom confined by a spherical cavity of finite barrier height. In addition, we have carried out kinetic energies, nuclear attraction energies, confining potential energies and probabilities of finding the electrons that occupy different subshells. In the strong and intermediate confinement regions, the results show that the barrier height of potential well and dot size have a strong influence on the energies and probabilities. The kinetic energies of electrons in 1s and nl orbitals increase as the height of the potential barrier increases, but in nuclear attraction energies the opposite behavior occurs. It is found that Coulomb and exchange energies rapidly decrease after the critical confinement radii, in which the electron in nl orbital escapes out of the well. The configuration-ionization confinement radius depends strongly on the potential barrier height.
  • Küçük Resim
    Öğe
    Energies of the ground and excited states of confined two-electron atom in finite potential well
    (Elsevier B.V., 2023) Demir, Celalettin; Çakır, Bekir; Yakar, Yusuf; Özmen, Ayhan
    For the ground and excited configurations, we have carried out the energy eigenvalues and corresponding wavefunctions of two-electron atom enclosed by finite confining potential by using Quantum Genetic Algorithm (QGA) procedure and Hartree-Fock Roothaan (HFR) method. Besides, we have analysed in detail orbital energies and probabilities of finding electron for the configurations 1S (1s2), 3S (1s2s), 3P (1s2p), 3D (1s3d) and 3F (1s4f). The results reveal that the potential barrier height plays a significant role on average energies, state energies, orbital energies and probabilities of finding electrons in orbitals. As dot size is extremely small and extremely large, the energies for 1snl configurations are getting close to each other, but between these two extreme situations they are separating from each other. While going to higher excited states, singlet and triplet states are almost the same due to the weakening of the exchange energy.
  • Küçük Resim
    Öğe
    Energy states, oscillator strengths and polarizabilities of many electron atoms confined by an impenetrable spherical cavity
    (Wiley, 2021) Yakar, Yusuf; Çakır, Bekir; Demir, Celalettin; Özmen, Ayhan
    We have calculated the ground and excited state energies and the orbital energies of three-electron atoms inside impenetrable spherical cavity. Energy eigenvalues and wavefunctions are calculated from the variational approximation method which is a combination of quantum genetic algorithm procedure and Hartree-Fock Roothaan method. In addition, the important parameters such as static and dynamic polarizability, oscillator strength and pressure have been investigated as perturbative. The results reveal that cavity radius and impurity charge have played an important role on the polarizability, the oscillator strength and pressure of the system. In addition, it is seen that when cavity radius is extremely large, all energies and the other physical parameters approach the values of a free space atom. As the dot radius decreases, the polarizability of system decreases due to the strong spatial confinement, but the pressure exerting on the system as the cavity radius R is shrunk increases. In addition, as the impurity charge increases, the oscillator strength decreases.
  • Küçük Resim
    Öğe
    Excited state energies, orbital energies and virial coefficients in Confined multi-electron systems
    (Elsevier B.V., 2022) Demir, Celalettin; Yakar, Yusuf; Çakır, Bekir; Özmen, Ayhan
    In the present study, the electronic structure of neutral He and Li atoms confined at the center of an impenetrable spherical cavity of varying radius has been investigated. Average, state, orbital energies and wave functions for the ground and excited state electron configurations 1snl (1s2nl)[n = 2, 3, 4 and l = 0, 1, 2 and 3] have been calculated using the method that is a combination of quantum genetic algorithm procedure and Hartree-Fock Roothaan. The atomic orbitals built up from Slater-type orbitals are used in calculations. The average state and orbital energies have been calculated for the first time for the higher excited states with nl [n = 3,4 and l = 1,2,3 for confined He atom and n = 3,4 and l = 0, 1,2,3 for confined Li atom]. The results show that impurity charge and spatial confinement have a great impact on orbital energies, average, state energies and virial coefficients of the system, especially in strong confinement region. In addition, it is seen that when cavity radius is extremely large, all state energies and virial coefficients approach the corresponding values of free atom.
  • Küçük Resim
    Öğe
    Investigation of electronic structure of a lithium atom confined by a finite spherical cavity
    (Elsevier B.V., 2023) Özmen, Ayhan; Çakır, Bekir; Demir, Celalettin; Yakar, Yusuf
    In this study, we have calculated the average energies of the ground and excited configurations of a lithium atom enclosed by a spherical potential well with finite barrier height, and we have also carried out calculations of orbital energies, confining potential energies and probabilities of finding the electrons in 1s and nl orbitals as a function of confinement radius for the 1s2nl configurations [nl = 2s, 2p, 3d and 4f]. Quantum Genetic Algorithm (QGA) and Hartree-Fock Roothaan (HFR) methods are used to calculate the energy eigenvalues and corresponding wave functions of the confined system. The results show that potential barrier height and confinement radius have a strong influence on the energies and the probabilities of finding the electrons inside and outside the well. It is found that 1s orbital energy increases suddenly at a critical confinement radius, at which the electron in nl orbital is trapped by the confining potential.
  • Küçük Resim
    Öğe
    Relativistic effects in confined helium-like atoms
    (Elsevier B.V., 2021) Yakar, Yusuf; Çakır, Bekir; Demir, Celalettin; Özmen, Ayhan
    The first-order relativistic effects such as relativistic correction to the kinetic energy, spin-orbit interaction and one-and two-body Darwin terms for the ground and excited states of confined H?, He, Li+ and Be++ atoms have been investigated. The results reveal that impurity charge and dot radius have a strong influence on the relativistic effects. In the strong confinement region, when the dot radius is further decreased, the magnitude of relativistic effects increases rapidly. Similarly, as the impurity charge increases, the relativistic effects increase substantially. In the electronic configuration 1,3S (1s2s), spin-orbit interaction energy and total Darwin energy for the case of triplet are lower than the singlet case. In addition, when the dot radius is large enough, the results for the relativistic effects approach to the corresponding values of free atom.