Electronic structure calculations are now indispensible for understanding chemical phenomena. Density functional theory (DFT), which is simple, conceptual, and applicable to large systems, has emerged as a powerful computational tool to tackle molecular electronic structures. DFT efficiently calculates electronic structure with high accuracy, and its algorithm is suitable for parallel computing...

In this work, the molecular conformation and vibrational analysis of 4-Amino-2, 2, 6, 6-tetramethylpiperidine (abbreviated as ATMP) were presented for the ground state using experimental techniques (FT-IR and FT-Raman) and the spectra were interpreted with the aid of normal coordinate analysis based on ab initio Hartree−Fock (HF) and density functional theory (DFT/B3LYP) methods with 6-311+G (d...

Conventional frontier molecular orbital theory is not able to satisfactorily explain the regioselectivity outcome of the nitrilimine-alkene cycloaddition. We considered that conceptual density functional theory (DFT) could be an effective theoretical framework to rationalize the regioselectivity of the title reaction. Several nitrilimine-alkene cycloadditions were analyzed, for which we could f...

the ir and nmr spectra were coupled with quantum chemical calculations in dft approach usingthe hybrid b3lyp exchange-correlation functional to confirm the structure of 2-methoxycarbonyl-7-methyl-1,3-thiazino[3,2-b][1,2,4]triazine-4,8-dione 2d.

A carboxylated adenosine analog (C-Ado−) has been synthesized and probed via time-resolved photoelectron spectroscopy in order to induce intra-molecular charge transfer from the carboxylic acid moiety nucleobase. Intra-molecular can be exploited as starting point probe low-energy electron (LEE) damage DNA its derivatives. Time-dependent density functional theory (TD-DFT) calculations at B3LYP-6...

the interaction of magnesium hydrate at the phosphate oxygen atom of the pyrimidine nucleotides (cmp,ump,dtmp) were studied at the hartree-fock level theory. we used lanl2dz basis set for mg and 6-31g* basis set for atoms.the basis set superposition error (bsse) begins to converge for used method/basis set. the gauge-invariant atomic orbital (giao) method and the continuous-set-of-gauge-transfo...

In this work, the FT-IR and FT-Raman spectra of 1-naphthaleneacetic acid methyl ester (abbreviated as 1-NAAME, C(10)H(7)CH(2)CO(2)CH(3)) have been recorded in the region 3600-10 cm(-1). The optimum molecular geometry, normal mode wavenumbers, infrared and Raman intensities, Raman scattering activities, corresponding vibrational assignments, Mullikan atomic charges and other thermo-dynamical par...

The vibrational fundamental modes of 7-methoxy4-bromomethylcoumarin (7BMC) have been analyzed by combining FTIR, FT-Raman and quantum chemical calculations. The structural parameters of the compound are determined from the optimized geometry by B3LYP method with 6-311++G (d, p) basis set. The harmonic vibrational frequencies were calculated and the scaled values have been compared with experime...

In quantum chemical computations the combination of Hartree-Fock or a density functional theory (DFT) approximation with relatively small atomic orbital basis sets of double-zeta quality is still widely used, for example, in the popular B3LYP/6-31G* approach. In this Review, we critically analyze the two main sources of error in such computations, that is, the basis set superposition error on t...

Quantum calculations of the physical properties (electronic and vibrational), based on density functional theory (DFT) method at B3LYP/6-31G** level of theory, were performed, by means of the Gaussian 09 set of programs, to investigate the effect of the addition of the radical CN on pyridazine molecules. The best geometry, the total energy, frontier molecular orbital energies (HOMO and HUMO), e...