The FT-IR and FT-Raman spectra of p-hydroxy-N-(p-methoxy benzylidene) aniline have been recorded in the region 4000-400 cm and 3500-100 cm, respectively. The optimized molecular geometry, vibrational frequencies in ground state have been calculated using density functional B3LYP methods (DFT) with 6-31+G(d,p) and 6-311++G(d,p) basis sets. The observed FT-IR and FT-Raman vibrational frequencies ...

We present the first analytic implementation of cubic and quartic force constants at the level of Kohn-Sham density-functional theory. The implementation is based on an open-ended formalism for the evaluation of energy derivatives in an atomic-orbital basis. The implementation relies on the availability of open-ended codes for evaluation of one- and two-electron integrals differentiated with re...

Cálculos B3LYP usando bases até 6-311G(3d2f,3p2d) foram utilizados para a previsão acurada de propriedades termoquímicas relacionadas à reação de dissociação trans-HONO(XA’) HO(XP) + NO(X P). Um estudo sistemático da influência da base foi realizado e resultados B3LYP foram comparados a dados experimentais e a outros resultados teóricos, calculados usando os métodos G2, G2MP2, CBS e métodos ab ...

The oxidation potentials for N-methyl substituted nucleic acid bases guanine, adenine, cytosine, thymine, uracil, xanthine, and 8-oxoguanine were computed using B3LYP and CBS-QB3 with the SMD solvation model. Acid-base and tautomeric equilibria present in aqueous solution were accounted for by combining standard redox potentials with calculated pKa and tautomerization energies to produce an ens...

The mechanism of the enantioselective deprotonation of cyclohexene oxide with isopinocampheyl-based chiral lithium amide was studied by quantum chemical calculations. The transition states of eight molecules were fully optimized at the ab initio HF/3-21G and density functional B3LYP/3-21G levels with Gaussian 98. The activation energies were calculated at the B3LYP/6-31+G(3df,2p)//B3LYP/3-21G l...

Geometric parameters and FT-IR spectrum of 6-bromo-8-thia-1,4epoxybicyclo[4.3.0]non-2-ene were computed by the HF, B3LYP, B3PW91 and mPW1PW91 methods in conjunction with the 6-31G(d,p) basis set. The calculated IR spectra are in a good agreement with the observed FT-IR spectrum. A general better performance of B3LYP, B3PW91 and mPW1PW91 versus HF was quantitatively characterized by using PAVF 1...

The structural and dynamical properties of NO3- in dilute aqueous solution have been investigated by means of two combined quantum mechanics/molecular mechanics (QM/MM) molecular dynamics simulations, namely HF/MM and B3LYP/MM, in which the ion and its surrounding water molecules were treated at HF and B3LYP levels of accuracy, respectively, using the DZV+ basis set. On the basis of both HF and...

The capabilities and limitations of the Becke-3-Lee-Yang-Parr (B3LYP) hybrid density functional are investigated as applied to studies of mixed-valent multinuclear oxomanganese complexes. Benchmark calculations involve the analysis of structural, electronic and magnetic properties of di-, tri- and tetra-nuclear Mn complexes, previously characterized both chemically and spectroscopically, includ...