We use ab initio pseudopotential total energy calculations with a plane wave basis set to investigate the structural energetics of various phases of polymorphic NbN. Particular attention is given to its recently discovered superconducting phase with a Tc of 16.4 K, reported to have the NbO structure type. Results of total energy calculations show that it is in fact energetically unfavorable for...

The reaction between niobium atom and acetaldehyde has been investigated with a DFT approach. Both ground and excited state potential energy surfaces are investigated in detail. The present results show that the title reaction starts with the formation of a η-CH3CHO-metal complex followed by C−C, aldehyde C−H, methyl C−H and C−O bond activation. These reactions can lead to several different pro...

Electron energy loss spectra in conjunction with near-edge fine structures of purely stoichiometric niobium monoxide (NbO) and niobium pentoxide (Nb2O5) reference materials were recorded. The structures of the niobium oxide reference materials were checked by selected area electron diffraction to ensure a proper assignment of the fine structures. NbO and Nb2O5 show clearly different energy loss...

Ultra-low sulfur steel has excellent resistance to pitting and hydrogen-induced cracking, is mainly used for gas pipeline steel, drilling structural parts of offshore platforms. This study reveals the limiting aspects desulfurization at slag–metal interface from perspective experimental theoretical calculations. Based on XPS results, quantitative analysis shows that relative contents Si O are d...

Reaction of 4-bromo-2-(((5-chloro-2-hydroxyphenyl) imino)methyl) phenol (H2L) with VOSO4 XH2O generates the oxido-vanadium(V) complex [VOL(OCH3)(OHCH3)], that characterized by FT-IR, UV–Vis, and elemental analysis. The complex was also characterized by single crystal X-ray diffraction crystallography. A DFT calculation was carried out on the complex using the B3LYP/ 6-31?G(d,p)method. The agree...

Density function M06 method has been used to optimize the geometries of shikonin -thymine at 6-311++G** basis. Finally, fourteen stabilized complexes have been obtained. Theories of atoms in molecules (AIM) and natural bond orbital (NBO) have been utilized to investigate the hydrogen bonds involved in all the systems. The interaction energies of all the complexes were corrected by basis set sup...

Formation of C–H H–B dihydrogen bonded complexes of acetylene, fluoroacetylene, chloroacetylene, and cyanoacetylene with borane-trimethylamine were investigated with MP2 and B3LYP methods using 6-311++G(d,p) and aug-cc-pVDZ basis sets. The stabilization energies ranged from 6–20 kJ mol . NBO analysis predicts transfer of charge from r B–H bonding orbital to r* C–H anti-bonding orbital. It was a...

Ab initio and DFT molecular orbital calculations predict that acetyl radical reacts with acetylene through interactions primarily involving the SOMO of the radical and the in-plane π-bond of acetylene. An energy barrier (∆E1) of 39.6 kJ mol‒1 is predicted for the preferred anti arrangement of reactants at the CCSD(T)/cc-pVDZ//BHandHLYP/cc-pVDZ level of theory. NBO analysis reveals additional in...

A study of the [C6 H6 Ir(PH3 )3 ]+ iridatropylium cation structure based on frontier orbital analysis, thermodynamic analysis, and natural bond orbital (NBO) theory is the main aim of the present research. Also, HOMO, LUMO energies, hardness, electrophilicity and chemical potential were calculated. Structural analysis indicated the optimized geometry shows a good agreement with the experimental...