equatorial/axial conversion in piperidine and phosphorinane with different substituents wereinvestigated with great details. three possible routes, i.e. heteroatom inversion and two ring inversiontype were considered. ring conversion can occur via two pathways one starts with ring flatteningfrom the heteroatom site (nitrogen in piperidine and phosphorous in phosphorinane) and the otherinitiates...

in this research, this possibility was investigated the relative stablilty geometry and bindingenergies of the hydrogen bonds of molybdate-phosphonic acid (mpa) complex in gas phase onthe basis of result of ab initio and dft calculations. three dft methods have been applied forcalculations are b3lyp, bp86 and b3pw91 that have been studied in two series of basis sets:d95** and 6-31+g(d,p) for hy...

Vertical excitation energies for DNA and RNA nucleosides are determined with electron structure calculations using the time-dependent density functional theory (TDDFT) method at the B3LYP/6-311++G(d,p) level for nucleoside structures optimized at the same level of theory. The excitation energies and state assignments are verified using B3LYP/aug-cc-pVDZ level calculations. The nature of the fir...

in this work, we report results of calculations based on the density functional theory of different species metal-ozone, containing mercury, silver and gold. the chosen species range from small molecules and large transition-metal containing ozone with mercury, silver and gold complexes. a comparative analysis of the description of the metal-oxygen bond obtained by different methodologies is pr...

in the present work, the quantum theoretical calculations of the molecular structure of the 1-(1, 3-benzothiazol-2-yl)-3-(thiophene-5-carbonyl) thiourea has been predicted and are evaluated using density functional theory (dft) in gas phase. the geometry of the title compound was optimized by b3lyp/6-311+g and b3lyp/6-311+g* methods and the experimental geometrical parameters of the title compo...

This work investigates the structural and nonlinear optical properties of a D-A type 1-[4-({(E)-[4-(methylsulfanyl)phenyl]methylidene}amino)phenyl]ethanone, MMP in which charge transfer occurs from -SCH3 donor to -COCH3 acceptor group through methylidene backbone; and some of its modeled analogues using quantum chemical calculations with pure BLYP and hybrid B3LYP correlation with high basis se...

Adiabatic ionization energy (AIE) calculations were performed at the AM1, PM3, PM6, PDDG, HF/QZVP, and B3LYP/QZVP levels of theory on 722 atmospherically relevant organic compounds with available experimental kOH . From the starting set of molecules, a final suite of 114 monoand polyfunctionalized compounds provided converged neutral and cationic geometries without imaginary frequencies for all...

Accurate (1)H chemical shifts of the -OH groups of polyphenol compounds can be calculated, compared to experimental values, using a combination of DFT, polarizable continuum model (PCM) and discrete solute-solvent hydrogen bond interactions. The study focuses on three molecular solutes: phenol, 4-methylcatechol and the natural product genkwanin in DMSO, acetone, acetonitrile, and chloroform. Ex...

The B3LYP/6-311+G(d)-SDD method, which considers the relativistic effect of bromine, was adopted for the calculations of the selected polybrominated diphenyl ethers (PBDEs) in the present study, in which the B3LYP/6-311+G(d) method was also applied. The calculated values and experimental data for structural parameters of the selected PBDEs were compared to find the suitable theoretical methods ...