Omar Al-Dossary | King Saud University (original) (raw)
Papers by Omar Al-Dossary
Journal of Advanced Physics, 2015
Russian Journal of Physical Chemistry A, 2014
ABSTRACT The potential energy curves have been calculated for the electronic states of the molecu... more ABSTRACT The potential energy curves have been calculated for the electronic states of the molecule LiK within the range 3 to 300 a.u., of the internuclear distance R. Using an ab initio method, through a semiempirical spin-orbit pseudo-potential for the Li (1s 2) and K (1s 22s 22p 63s 23p 6) cores and core valence correlation correction added to the electrostatic Hamiltonian with Gaussian basis sets for both atoms. The core valence effects including core-polarization and core-valence correlation are taken into account by using an l-dependent core-polarization potential. The molecular orbitals have been derived from self-consistent field (SCF) calculation. The spectroscopic constants, dipole moments and vibrational levels of the lowest electronic states of the LiK molecule dissociating into K (4s, 4p, 5s, 3d, and 5p) + Li (2s, 2p, 3s, and 3p) in 1, 3Σ, 1, 3Π, and 1, 3Δ symmetries. Adiabatic results are also reported for 2Σ, 2Π, and 2Δ electronic states of the molecular ion LiK+ dissociating into Li (2s, 2p, 3s, and 3p) + K+ and Li+ + K (4s, 4p, 5s, 3d, and 5p). The comparison of the present results with those available in the literature shows a very good agreement in spectroscopic constants of some lowest states of the LiK and LiK+ molecules, especially with the available theoretical works. The existence of numerous avoided crossing between electronic states of 2Σ and 2Π symmetries is related to the charge transfer process between the two ionic systems Li+K and LiK+.
Journal of Physics: Conference Series, 2012
ABSTRACT If coherent superpositions such as the symmetry eigenstates gerade and ungerade are in t... more ABSTRACT If coherent superpositions such as the symmetry eigenstates gerade and ungerade are in turn coherently superimposed, localization occurs. This effect is studied by the intensities of the Doppler components of electrons emitted from dissociating fragments of superexcited O2. The measurements show clear evidence for such coherent localization.
Journal of Physics: Conference Series, 2012
ABSTRACT The valence electrons of fullerenes may be regarded as spherical distributions with a fi... more ABSTRACT The valence electrons of fullerenes may be regarded as spherical distributions with a finite width of a jellium-like potential giving rise to collective motions of this orange peel electron cloud. They cause strong enhancement of the photoionization cross section, a resonant behavior phenomenon know as plasmon excitations. The number and characteristic features of these excitations will be discussed.
Journal of Electron Spectroscopy and Related Phenomena, 2011
ABSTRACT
Journal of Computational and Theoretical Nanoscience, 2011
ABSTRACT Many-body interaction potential energy function is used to predict the structural stabil... more ABSTRACT Many-body interaction potential energy function is used to predict the structural stability and cohesive energy of Molybdenum (Mo) and Tungsten (W) spherical metallic nanocrystals by computer simulations. The model proposed is Ercok's potential energy function comprising two- and three-body terms. The model applies successfully to BCC elements and predicts the size dependence of the cohesive energy of nanocrystals. This prediction agrees with experimental measurements on Mo and W.
International Journal of Modern Physics A, 2007
The asymptotic iteration method is used to calculate the eigenenergies for the asymmetrical quant... more The asymptotic iteration method is used to calculate the eigenenergies for the asymmetrical quantum anharmonic oscillator potentials V (x) = 2α j=2 A j x j , with (α = 2) for quartic, and (α = 3) for sextic asymmetrical quantum anharmonic oscillators. An adjustable parameter β is introduced in the method to improve its rate of convergence. Comparing the present results with the exact numerical values, and with the numerical results of the earlier works, it is found that asymptotically, this method gives accurate results over the full range of parameter values A j .
Canadian Journal of Physics, 2006
The asymptotic iteration method is applied, to calculate the angular spheroidal eigenvalues λ m ℓ... more The asymptotic iteration method is applied, to calculate the angular spheroidal eigenvalues λ m ℓ (c) with arbitrary complex size parameter c. It is shown that, the obtained numerical results of λ m ℓ (c) are all in excellent agreement with the available published data over the full range of parameter values ℓ, m, and c. Some representative values of λ m ℓ (c) for large real c are also given.
International Journal of Nanoscience, 2007
ABSTRACT We investigate the effect of Mie-type potential range on the cohesive energy of metallic... more ABSTRACT We investigate the effect of Mie-type potential range on the cohesive energy of metallic nanoparticles using the size-dependent potential parameters method. The predicted cohesive energy for different cubic structures is observed to decrease with decreasing the particle size, and increase with decreasing the range of the interatomic potential, a result which is in the right direction at least to predict the experimental values of Molybdenum and Tungsten nanoparticles.
Czechoslovak Journal of Physics, 2006
Exact solutions for vibrational levels of diatomic molecules via the Morse potential are obtained... more Exact solutions for vibrational levels of diatomic molecules via the Morse potential are obtained by means of the asymptotic iteration method. It is shown that, the numerical results for the energy eigenvalues of 7 Li 2 are all in excellent agreement with the ones obtained before. Without any loss of generality, other states and molecules could be treated in a similar way. PACS number(s): 03.65.Ge
Journal of Physics B: Atomic, Molecular and Optical Physics, 2009
The size-dependent potential parameters method is used to investigate the effect of many-body int... more The size-dependent potential parameters method is used to investigate the effect of many-body interactions on the structural stabilities and the cohesive energy of molybdenum (Mo) and tungsten (W) spherical metallic nanoparticles. The total interaction energy is represented in terms of a two-body Mie-type potential plus a three-body Axilord-Teller-type potential. Results emphasized the importance of multi-body forces to explain nano-structures. The predicted cohesive energy for these nanoparticles is observed to decrease with decreasing sizes, a result which is in agreement with experimental results.
Journal of Russian Laser Research, 2009
Adiabatic potential energy, spectroscopic constants, dipole moments, and vibrational levels of th... more Adiabatic potential energy, spectroscopic constants, dipole moments, and vibrational levels of the lowest electronic states of the alkali dimer LiNa molecule dissociating into Na (3s, 3p, 4s, 3d, and 4p) + Li (2s, 2p, 3s, and 3p) in 1,3Σ, 1,3Π, and 1,3Δ symmetries are presented. Adiabatic results are also reported for 2Σ, 2Π, and 2Δ electronic states of the molecular ion LiNa+ dissociating into Li (2s, 2p, 3s, and 3p) + Na+ and Li+ + Na(3s, 3p, 4s, 3d, and 4p). We use an ab initio approach involving a non-empirical pseudopotential for the Li (1s2) and Na (1s22s22p6) cores and core valence correlation correction. A very good agreement is obtained for some lowest states of the LiNa and LiNa+ molecules for spectroscopic constants with the available theoretical works. The existence of numerous avoided crossings between electronic states of 2Σ and 2Π symmetries is related to the charge transfer process between the two ionic systems Li+Na and LiNa+.
Journal of Advanced Physics, 2015
Russian Journal of Physical Chemistry A, 2014
ABSTRACT The potential energy curves have been calculated for the electronic states of the molecu... more ABSTRACT The potential energy curves have been calculated for the electronic states of the molecule LiK within the range 3 to 300 a.u., of the internuclear distance R. Using an ab initio method, through a semiempirical spin-orbit pseudo-potential for the Li (1s 2) and K (1s 22s 22p 63s 23p 6) cores and core valence correlation correction added to the electrostatic Hamiltonian with Gaussian basis sets for both atoms. The core valence effects including core-polarization and core-valence correlation are taken into account by using an l-dependent core-polarization potential. The molecular orbitals have been derived from self-consistent field (SCF) calculation. The spectroscopic constants, dipole moments and vibrational levels of the lowest electronic states of the LiK molecule dissociating into K (4s, 4p, 5s, 3d, and 5p) + Li (2s, 2p, 3s, and 3p) in 1, 3Σ, 1, 3Π, and 1, 3Δ symmetries. Adiabatic results are also reported for 2Σ, 2Π, and 2Δ electronic states of the molecular ion LiK+ dissociating into Li (2s, 2p, 3s, and 3p) + K+ and Li+ + K (4s, 4p, 5s, 3d, and 5p). The comparison of the present results with those available in the literature shows a very good agreement in spectroscopic constants of some lowest states of the LiK and LiK+ molecules, especially with the available theoretical works. The existence of numerous avoided crossing between electronic states of 2Σ and 2Π symmetries is related to the charge transfer process between the two ionic systems Li+K and LiK+.
Journal of Physics: Conference Series, 2012
ABSTRACT If coherent superpositions such as the symmetry eigenstates gerade and ungerade are in t... more ABSTRACT If coherent superpositions such as the symmetry eigenstates gerade and ungerade are in turn coherently superimposed, localization occurs. This effect is studied by the intensities of the Doppler components of electrons emitted from dissociating fragments of superexcited O2. The measurements show clear evidence for such coherent localization.
Journal of Physics: Conference Series, 2012
ABSTRACT The valence electrons of fullerenes may be regarded as spherical distributions with a fi... more ABSTRACT The valence electrons of fullerenes may be regarded as spherical distributions with a finite width of a jellium-like potential giving rise to collective motions of this orange peel electron cloud. They cause strong enhancement of the photoionization cross section, a resonant behavior phenomenon know as plasmon excitations. The number and characteristic features of these excitations will be discussed.
Journal of Electron Spectroscopy and Related Phenomena, 2011
ABSTRACT
Journal of Computational and Theoretical Nanoscience, 2011
ABSTRACT Many-body interaction potential energy function is used to predict the structural stabil... more ABSTRACT Many-body interaction potential energy function is used to predict the structural stability and cohesive energy of Molybdenum (Mo) and Tungsten (W) spherical metallic nanocrystals by computer simulations. The model proposed is Ercok's potential energy function comprising two- and three-body terms. The model applies successfully to BCC elements and predicts the size dependence of the cohesive energy of nanocrystals. This prediction agrees with experimental measurements on Mo and W.
International Journal of Modern Physics A, 2007
The asymptotic iteration method is used to calculate the eigenenergies for the asymmetrical quant... more The asymptotic iteration method is used to calculate the eigenenergies for the asymmetrical quantum anharmonic oscillator potentials V (x) = 2α j=2 A j x j , with (α = 2) for quartic, and (α = 3) for sextic asymmetrical quantum anharmonic oscillators. An adjustable parameter β is introduced in the method to improve its rate of convergence. Comparing the present results with the exact numerical values, and with the numerical results of the earlier works, it is found that asymptotically, this method gives accurate results over the full range of parameter values A j .
Canadian Journal of Physics, 2006
The asymptotic iteration method is applied, to calculate the angular spheroidal eigenvalues λ m ℓ... more The asymptotic iteration method is applied, to calculate the angular spheroidal eigenvalues λ m ℓ (c) with arbitrary complex size parameter c. It is shown that, the obtained numerical results of λ m ℓ (c) are all in excellent agreement with the available published data over the full range of parameter values ℓ, m, and c. Some representative values of λ m ℓ (c) for large real c are also given.
International Journal of Nanoscience, 2007
ABSTRACT We investigate the effect of Mie-type potential range on the cohesive energy of metallic... more ABSTRACT We investigate the effect of Mie-type potential range on the cohesive energy of metallic nanoparticles using the size-dependent potential parameters method. The predicted cohesive energy for different cubic structures is observed to decrease with decreasing the particle size, and increase with decreasing the range of the interatomic potential, a result which is in the right direction at least to predict the experimental values of Molybdenum and Tungsten nanoparticles.
Czechoslovak Journal of Physics, 2006
Exact solutions for vibrational levels of diatomic molecules via the Morse potential are obtained... more Exact solutions for vibrational levels of diatomic molecules via the Morse potential are obtained by means of the asymptotic iteration method. It is shown that, the numerical results for the energy eigenvalues of 7 Li 2 are all in excellent agreement with the ones obtained before. Without any loss of generality, other states and molecules could be treated in a similar way. PACS number(s): 03.65.Ge
Journal of Physics B: Atomic, Molecular and Optical Physics, 2009
The size-dependent potential parameters method is used to investigate the effect of many-body int... more The size-dependent potential parameters method is used to investigate the effect of many-body interactions on the structural stabilities and the cohesive energy of molybdenum (Mo) and tungsten (W) spherical metallic nanoparticles. The total interaction energy is represented in terms of a two-body Mie-type potential plus a three-body Axilord-Teller-type potential. Results emphasized the importance of multi-body forces to explain nano-structures. The predicted cohesive energy for these nanoparticles is observed to decrease with decreasing sizes, a result which is in agreement with experimental results.
Journal of Russian Laser Research, 2009
Adiabatic potential energy, spectroscopic constants, dipole moments, and vibrational levels of th... more Adiabatic potential energy, spectroscopic constants, dipole moments, and vibrational levels of the lowest electronic states of the alkali dimer LiNa molecule dissociating into Na (3s, 3p, 4s, 3d, and 4p) + Li (2s, 2p, 3s, and 3p) in 1,3Σ, 1,3Π, and 1,3Δ symmetries are presented. Adiabatic results are also reported for 2Σ, 2Π, and 2Δ electronic states of the molecular ion LiNa+ dissociating into Li (2s, 2p, 3s, and 3p) + Na+ and Li+ + Na(3s, 3p, 4s, 3d, and 4p). We use an ab initio approach involving a non-empirical pseudopotential for the Li (1s2) and Na (1s22s22p6) cores and core valence correlation correction. A very good agreement is obtained for some lowest states of the LiNa and LiNa+ molecules for spectroscopic constants with the available theoretical works. The existence of numerous avoided crossings between electronic states of 2Σ and 2Π symmetries is related to the charge transfer process between the two ionic systems Li+Na and LiNa+.