Quantum mechanical calculations of energies, geometries and vibrational wavenumbers of 4-nitroaniline (4NA) were carried out by using Density functional theory (DFT /B3LYP/6-311++G(d,p)/ CC-pvdz / Aug-cc-Pvdz) method. The optimized geometrical parameters obtained by B3LYP method show good agreement with experimental X-ray data. The best level of theory in order to reproduce the experimental wav...

DFT(B3LYP, B3PW91) calculations in conjunction with three different basis sets have been utilized to investigate the variations in the bond lengths, dipole moment, rotational constants, IR frequencies, IR intensities and rotational invariants of ClCCCN. The nuclear quadrupole constants of chlorine ((35)Cl, (37)Cl) and nitrogen ((14)N) of ClCCCN have been calculated on the experimental r(s) stru...

The infrared vibrational absorption (VA) and vibrational circular dichroism (VCD) spectra of methyl lactate in carbon tetrachloride and methanol have been measured in the 1000-1800 cm region. Noticeable changes due to the solute self-aggregation and solvent-solute intermolecular hydrogen-bonding in the reported spectra have been detected. A series of density functional theory (DFT/B3LYP/6-311++...

The structure of coumaran (2,3-dihydrobenzofuran) is characterized by a non-planar skeleton, due to the position of the most far apart carbon in the dihydrofuran ring. We have measured 133 , and type lines of the rotational spectrum in the millimeter-wave region (59-78GHz), characterized by a doubling typical of an inversion motion such as the ring-puckering of the five-membered ring. By using ...

A theoretical study is presented on the mechanism of OH reactions with three unsaturated aldehydes, relevant to atmospheric chemistry. Using acrolein as test molecule, several methods were tested in conjunction with the 6-311 ++ G(d,p) basis set. Based on the results from this study, the MPWB1K and M05-2X functionals were selected for the further study of acrolein, methacrolein and crotonaldehy...

A stochastic exploration of the quantum conformational space for the (H(2)O)(n)Li(+), n = 3, 4, 5 complexes produced 32 molecular clusters at the B3LYP/6-311++G** and MP2/6-311++G** levels. The first solvation shell is predicted to comprise a maximum of 4 water molecules. Energy decomposition analyses were performed to determine the relationship between the geometrical features of the complexes...

The cysteine anion was produced in the gas phase by electrospray ionization and investigated by photoelectron spectroscopy at low temperature (70 K). The cysteine anion was found to exhibit the thiolate form [-SCH2CH(NH2)CO2H], rather than the expected carboxylate form [HSCH2CH(NH2)CO2-]. This observation was confirmed by two control experiments, that is, methyl cysteine [CH3SCH2CH(NH2)CO2-] an...

High level Density Functional Theory (DFT) using B3LYP/6-311++G(2df,2p)//6-311+G(d,p) calculations on the relative stabilities and structures of the neutral, protonated and deprotonated isorhodanine tautomeric forms are reported in the gas phase and solution. Gas phase and solution B3LYP calculations predict that the oxo/thione tautomer is the most stable one in all cases. Comparison of the gas...

The Molecular structure, conformational stability and vibrational frequencies of succinonitrile NCCH2CH2CN have been investigated with ab initio and density functional theory (DFT) methods implementing the standard 6-311++G* basis set. The potential energy surfaces (PES) have been explored at DFT-B3LYP, HF and MP2 levels of theory. In agreements with previous experimental results, the molecule ...

The conformational stability and vibrational infrared and Raman spectra of trichloroacetyl isocyanate (CCl3CONCO) were investigated by ab initio MP2 and density functional B3LYP calculations using the 6-311++G** basis set. From the potential energy scans of the internal rotations in both the halomethyl and the isocyanate rotors, the molecule was predicted to exist predominantly in the cis-cis c...