Abraham F. Jalbout

Monte Carlo simulation on the indirect exchange interactions of Co-doped ZnO film

Monte Carlo simulations using a three-dimensional lattice model studied the Ruderman–Kittel–Kasuya–Yosida (RKKY) indirect exchange interaction of doped magnetic Co ions in ZnO films. The results of the calculations show that the RKKY interaction in Co-doped ZnO is long ranged and its magnitude is proportional to R−1 (inverse of the distance R from a central Co2+ ion). The sign oscillates with a frequency that depends on the concentration of the carrier. The long-distance sum of the RKKY indirect exchange energies is positive indicating that these materials are ferromagnetic, in direct correlation with previously reported results.

Gaussian-based computations in molecular science

A review article of over 300 hundred references describing the background and recent advances in the development and application of Gaussian based methods is presented.

Theoretical and experimental vibrational analysis of [C6H5NH3]2SiF6

Phenylammonium hexafluorosilicate ([C6H5NH3]2SiF6) single-crystal compound was synthesized by us; and it crystallized in orthorhombic system with Pmmm (Z=2) as space group. The vibrational spectra of this compound were recorded and discussed. Strong hydrogen bonding in this compound is indicated by overtone and combination modes possessing appreciable intensities. The results are compared to semi-empirical PM3 and B3LYP density functional theory (DFT) calculations. Full thermodynamic properties and geometries are also located and characterized.

Vibrational analysis and ionization potentials of XCH3 (X=Be,Mg,Ca) calculated by hybrid density functional theory and high order ab initio methods

Abstract The amount of attention dedicated to the theoretical and experimental investigation of small cationic organometallic systems in the literature is very limited. In this Letter we use the B3LYP method with a variety of basis sets as well as the very advanced CBS-Q, CBS-QB3, G1, G2MP2, G2, G3, and G3B3 ab initio methods in order to analyze the vibrational spectra as well as ionization potentials of BeCH 3 ,MgCH 3 and CaCH 3 . The need for further addition of experimental data to the archives for these systems is discussed, as well as recommendations for which theoretical methods are optimum for a particular result.

Part II. Gaussian, complete basis set and density functional theory stability evaluation of the singlet states of Cn (n=1–6): energy differences, HOMO–LUMO band gaps, and aromaticity

Although the neutral forms of these carbon clusters have been investigated, no studies regarding the less stable singlet forms have been performed. In this manuscript, the stability properties of these clusters will be examined with the advanced CBS-Q, G2, G3, G3B3 high level ab initio methods as well as the density functional theory B3LYP/6-311++G (3df, 3pd) method.

Bond order weighted hyper-Wiener index

Abstract In this work the hyper-Wiener index calculated and are weighted by Mulliken bond orders. We have considered several formaldehyde derivatives to try to relate these values to an actual physical property (vibrational frequencies in this case). This was done in order to establish a relation between the quantities.

Density functional theory analysis of CaRgn+ complexes: (Rg=He, Ne, Ar; n=1–4)

Abstract CaRg n + (Rg=He, Ne, Ar) complexes with n =1–4, are investigated by performing using the B3LYP/6-311+G (3df) density functional theory calculations. The CaHe n + ( n =1–4) complexes are found to be stable. In the case of CaNe n + and CaAr n + , stable structures and stationary point were found only for n =1 and 2. For n =3 in the C 3 V and the D 3 h point group as well as for n =4 in the T d (tetrahedral) point group a saddle point (imaginary frequency) is observed and global minimum could be obtained along the potential energy surface.

Electron-conformational study for the structure-hallucinogenic activity relationships of phenylalkylamines

The structure-hallucinogenic activity relationships of a series of phenylethylamine and phenylisopropylamine derivatives have been investigated in the frameworks of electron-conformational method. The calculated geometry and electronic structure parameters accompanying to each atom and bond of each molecule in view were arranged as a matrix called electron-conformational matrix of contiguity (ECMC). The features that are responsible for strong and weak activity demonstrations have been found as submatrices of ECMCs belonging to some template compounds. Two electron-conformational features present in nonhallucinogenic compounds have been revealed. A quantitative model has been improved for predicting hallucinogenic activity numerically. A test series was used to verify the results obtained.

Part II. Ionization energies, hardness, softness, and absolute electronegativity of heteronuclear and homonuclear diatomic molecules by the CBS-QB3 and G3B3 methods

Previously we have shown that the CBS-QB3 and G3B3 methods have been excellent in the calculation of the electron affinity of small diatomic molecules [J. Mol. Struct. (THEOCHEM) 574 (2001) 141]. In this work, we examine the ionization energies, and use the reported values of the electron affinity to compare the CBS-QB3 and G3B3 values of the hardness, softness and absolute electronegativity. Excellent experimental agreement is obtained for most of our calculated values.

The H2CO potential energy surface: advanced ab initio and density functional theory study

Abstract The ground state potential energy surface of formaldehyde (H 2 CO) was investigated with a variety of Gaussian based ab initio methods (G2, CBS-Q, CBS-QB3, G3, G3B3) as well as the B3LYP density functional theory with small (6-31G(d), as implemented in the G3B3 method) to the very large 6-311++G(3df, 3pd) basis set. In this work, we have considered the decomposition of H 2 CO into H 2 +CO (with an average theoretical to experimental error of around 1.5%), as well as the isomerization barriers, activation barriers and heats of reaction.