Kh.M. Eid

FT-IR spectroscopic analyses of 2-(2-furanylmethylene) propanedinitrile

In the present work, a computational study for the optimized molecular structural parameters, thermo-chemical parameters, total dipole moment, HOMO-LUMO energy gap and a combined experimental and computational study for FT-IR spectra for 2-(2-furanylmethylene) propanedinitrile have been investigated using B3LYP utilizing 6-31G and 6-311G basis set. Our calculated results showed that the investigated compound possesses a dipole moment of 7.5D and HOMO-LUMO energy gap of 3.92eV using B3LYP/6-311G which indicates that our investigated compound is highly applicable for photovoltaic solar cell applications.

Vibrational spectroscopic analysis of 2-chloro-5-(2,5-dimethoxy-benzylidene)-1,3-diethyl-dihydro-pyrimidine-4,6(1H,5H)-dione.

In the present work, a combined experimental and computational study for the optimized molecular structural parameters, FT-IR spectra, thermo-chemical parameters, total dipole moment and HOMO-LUMO energy gap for 2-chloro-5-(2,5-dimethoxy-benzylidene)-1,3-diethyl-dihydro-pyrimidine-4,6(1H,5H)-dione have been investigated using B3LYP/6-311G basis set. Our calculated results have showed that the investigated compound possesses a dipole moment of 4.9 Debye and HOMO-LUMO energy gap of 3 eV which indicate high recommendations for photovoltaic devices fabrication.

Many body expansion and ion diffusion in LiH crystal

A finite LiH lattice whose Madelung potential in the central region closely approximates the Madelung potential in the host crystal is constructed. Hartree-Fock calculations were then carried out on lithium hydride clusters both within the crystal and as isolated species. The many body expansion terms and the probability of ionic motions which result in diffusion are examined and relaxation around diffused ions is taken into account. Calculations confirm that the many body expansion terms in the crystal environment are both convergent and smaller than for the isolated clusters. The two-ion rotation mechanism is the most probable. The barrier height for cation diffusion is less than for anion diffusion suggesting easier transfer of cations rather than anions within the LiH crystal. The results are correlated with those reported previously on LiF crystal.

Ground and excited state properties of many-body energies in Li n+ n F- ions

Ground and excited state properties of many body energies in Li n+ n F - ions were examined at two levels of ab initio theory. The effect of basis set size at configurations specified by two angular variables was tested. The ions in the excited state lattice were found to be more bound than those in the ground state. Discrepancies were observed between the minimal and extended basis set for describing the multibody expansions. Although the ground state V(m, n) terms at m = n ≥ 3 were negligible, the excited state V(m, n) terms at m = n ≥ 3 were not negligible.

Potential energy curves of H and H− interactions with He

Abstract Potential energy curves of H and H − interactions with He have been computed using a quadratic configuration interaction method and universal even-tempered basis sets. The effects of bond function augmentation are considered. Crossing radius and total cross section were calculated to be 2.527 a 0 and ∼ 5.6 × 10 −16 cm 2 in closer agreement with the experimental determination of 1.997 a 0 –2.387 a 0 and ∼ 3.5–5.0 × 10 −16 cm 2 than the previously reported ab initio estimates. Bond function augmentation enhances the agreement with experiment as far as crossing radius and total electron detachment cross sections are concerned. Potential curves were fitted to analytical potentials to decompose the threshold energy at the crossing radius into its major components.

An ab initio approach to many-body energies and Be2+V- dipoles in LiH crystal and clusters

A finite LiH crystal whose Coulomb potential in the central region closely approximates the Madelung potential in the unit cell of the host crystal is constructed. The beryllium ion is then introduced to initiate the Be2+V- dipole and to examine the perfect and defect properties of LiH clusters both within the crystal and as isolated species. These include the convergence properties of many-body energies, the defect formation mechanism and hydride ion migration. Crystal field and overlap effects are examined. Lattice relaxation around defect sites is allowed and the optimal relaxation mode is assigned. Dipole aggregates, the cluster-lattice interaction, defect formation energies, the free rotation of the Be2+V- dipole in two perpendicular planes, the energy of rotation of the cation vacancy around Be2+ and the tendency of Be2+ to associate with the cation vacancy are examined and explained in relation to their scientific and technological importance.

Bulk dislocation-U defect interaction, surface excitons and adsorptivity of atomic H on dislocated surfaces of LiH crystal: ab initio calculations

An ab initio embedded cluster method was used to examine the bulk dislocation-U defect interaction, surface excitons and the adsorptivity of atomic H on dislocated surfaces of LiH using the Hartree-Fock approximation and the second-order Moller-Plesset perturbation correction. In the LiH crystal bulk, the results confirm: (1) U1 and U2 centres make dislocations more facile, (2) dislocation processes do not reduce the ionic conductivity of highly populated edge centred hydride interstitials and (3) the dislocation-U defect interaction increases monotonically in the series face→volume→edge centred interstitial structures. On LiH crystal surfaces the results confirm: (1) the exclusive dependence of band gaps and exciton bands on dislocation, (2) the strongest adsorption of atomic H on a surface is associated with X-dislocations, (3) dislocations are unable to change the nature of physical adsorption to chemical adsorption and (4) the mobility of atomic H over the Z-dislocated surface is more facile than that over the X-dislocated surface. As X-surface dislocation proceeds, the HOMO and LUMO levels of the substrate shift to higher energies and the band gap becomes narrower. This change in the electronic structure suggests that charge transfer from the X-dislocated surface is more facile in the course of adsorbate-substrate interaction.