The relative stability of hydrogen-bonded of Molybdate-Phosphonic Acid (MPA) complex (1:2) ingas phase has been carried out using Density Functional Theory (DFT) methods. The methods are usedfor calculations are B3LYP, BP86 and B3PW91 that have been studied in two series of basis sets: D95**and 6-31+G(d,p) for hydrogen and oxygen atoms; LANL2DZ for Mo and Phosphorus. Predictedhydrogen-bond geom...

The structures and properties of [n]sila-acenes (n=2-4) were investigated by density functional theory method. The results of calculations were obtained at B3LYP/6-311G (d,p) level on model species. Energetic criteria suggest that 2-1b (n=2), 3-1b (n=3), and 4-1b (n=4) isomers enjoy stabilization. By frontier orbital analysis, these systems are among the most stable of the family. Also, calcula...

Density functional theory (DFT) calculations have been performed to investigating the effects of themolecular oxygen impurity on the quadrupole coupling constant (Qcc) parameters of armchair and zigzagboron nitride nanotubes (BNNTs). Optimization processes have been performed to relax the original andimpure structures of the investigated BNNTs. Afterwards, the Qcc parameters have been evaluated...

structural and magnetic properties of purine and pyrimidine nucleotides (cmp, ump, dtmp, amp, gmp, imp) were studied at different levels of ab initio molecular orbital theory. these calculations were performed at the hartree-fock level and density functional b3lyp methods. geometries were fully optimized by following cs symmetry restrictions. the standard 6-31g** basis set which includes polari...

In this paper, we have used density functional perturbation theory (DFPT) and Pseudo-potential method to calculate the phonon spectrum, phonon density of states (DOS), specific heat capacity and mechanical properties of (5,5) armchair and (9,0) zigzag Single Wall Carbon Nanotubes (SWCNTs). Our calculations show that Young’s modulusfor (5,5) and (9,0) nanotubesare higher than 1TPa. We have also ...

The N-(2-benzoyl-phenyl) oxalyl derivatives are important models for studying of three-centered intramolecular hydrogen bonding in organic molecules. The quantum theoretical calculations for two crystal structures of N-(2-benzoyl-phenyl) oxalyl (compounds I and II) were performed by Density Functional Theory (B3LYP method and 6-311+G* basis set). From the optimized structures, geometric paramet...

importance of covalent bonded two-dimensional monolayer nanostructures and also hydrocarbons is undeniably responsible for creation of new fascinating materials like polyphenylene polymer, a hydrocarbon super honeycomb network, so-called porous graphene. the mechanical properties of porous graphene such as its young’s modulus, poisson’s ratio and the bulk modulus as the determinative properties...