Computational studies on three tautomeric forms of four 1,5,6,7-tetrahydro- 4H-indazol-4-one derivatives: 1,5,6,7-tetrahydro-4H-indazol-4-one (1), 6,6-dimethyl- 1,5,6,7-tetrahydro-4H-indazol-4-one (2), 3-methyl-1,5,6,7-tetrahydro-4H-indazol-4-one (3) and 3,6,6-trimethyl-1,5,6,7-tetrahydro-4H-indazol-4-one (4), have been performed at different levels, ranging from semiempirical AM1, ab initio Ha...

In this paper we report the synthesis of 2-((E)-1-(2-((E)-1-(2-hydroxyphenyethylideneamino) phenylamino) ethyl) phenol.In addition to its synthesis we present AM1 and B3LYP/6-31G* calculations to characterize the physical properties of this molecule. Finally, the antifungal and antibacterial activities of this derivative have been evaluated Introduction Schiff bases are an important class of li...

First-principles anharmonic calculations are carried out for the IR and Raman spectra of the CAH stretching bands in butane. The calculations use the Vibrational Self-Consistent Field (VSCF) algorithm. The results are compared with gas-state experiments. Very good agreement between the computed and experimental results is found. Theory is successful also in computing a weak peak which is caused...

Converged approximate density functional calculations usually do not bind anions due to large self-interaction error. But Hartree-Fock (HF) calculations have no such problem, producing negative HOMO energies. Thus, electron affinities can be calculated from density functional total energy differences using approximations such as PBE and B3LYP, evaluated on HF densities (for both anion and neutr...

Differential and integral cross section measurements, for incident electron energies in the 20-50 eV range, are reported for excitation of several composite vibrational modes in α-tetrahydrofurfuryl alcohol (THFA). Optimisation and frequency calculations, using GAUSSIAN 09 at the B3LYP/aug-cc-pVDZ level, were also undertaken for the two most abundant conformers of THFA, with results being repor...

In this study, we employed ONIOM calculations to study functionalized single-wall carbon nanotubes (SWCNTs), for assessing an appropriate level of theory for accurate binding energies calculations, particularly by considering ozone adsorption and arylation. Although ONIOM models reproduced the binding energies and geometries in relatively good agreement with the density functional theory B3LYP/...

For studying both hydrogen bond and dipole-dipole interactions between methanol molecules (self-association) the geometry of clusters of increasing numbers of methanol molecules (n = 1,2,3) were optimized and also their vibrational frequencies were calculated with quantum chemical methods. Beside these B3LYP/6-311G** calculations, PCM calculations were also done for all systems with PCM at the ...

Gas-phase activation energies were calculated for three lithium enolate reactions by using several different ab initio and density functional theory (DFT) methods to determine which levels of theory generate acceptable results. The reactions included an aldol-type addition of an enolate to an aldehyde, a proton transfer from an alcohol to a lithium enolate, and an S(N)2 reaction of an enolate w...

Density Functional Theory (DFT) calculations were employed to investigate the structural characteristics, electronic properties, and nonlinear optical properties of Benzyne-Based Chromophores at B3LYP/6-31G(d,p) level. The effects on the hyperpolarizabilities of various donor and acceptor substituent (H, F, Cl, Br, Me, NH2, OH, NH3+, COOH, CHO, CN, NO,NO2 ) were studied. The results reveale...

The Density Functional Theory (DFT) and the Natural Bond Orbital (NBO) calculations basedmethod B3LYP/6-31G* were carried out to study the interaction of carbon nanotube (8,0) withnitrobenzene in two situations perpendicular and parallel. Formation energies of compounds,charges, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular'orbital (LUMO) and the HOMO-LUMO ba...