A detailed analysis of the selected DFT functionals for the calculations of interaction-induced dipole moment, polarizability and first-order hyperpolarizability has been carried out. The hydrogen-bonded model chains consisting of HF, H(2)CO and H(3)N molecules have been chosen as a case study. The calculations of the components of the static electric properties using the diffuse Dunning's basi...

The application domain of accurate and efficient CE-B3LYP and CE-HF model energies for intermolecular interactions in molecular crystals is extended by calibration against density functional results for 1794 molecule/ion pairs extracted from 171 crystal structures. The mean absolute deviation of CE-B3LYP model energies from DFT values is a modest 2.4 kJ mol-1 for pairwise energies that span a r...

We use a combination of Time-Dependent Density Functional Theory (TD-DFT) and approximate Coupled Cluster Theory (RI-CC2) to compare trends in the optical gap and fluorescence energies of ortho-, meta- and para-oligomers of phenylene. We find that RI-CC2 and TD-DFT calculations using three different commonly employed XC-potentials (B3LYP, BHLYP and CAM-B3LYP) generally give consistent predictio...

The density functional theory (DFT) method combined with B3LYP and B3PW91 hybrid were utilized for geometrical optimization, vibrational frequencies electronic spectral study. levels of the time dependent-DFT 6–311+G(d, p) basis set have been used to determine highest occupied molecular orbital (HOMO) – lowest unoccupied (LUMO) energies, absorption wavelengths, properties (total energy gap) 4-(...

In order to investigate the selective catalytic reduction of NOx by hydrocarbons, Ag/Al2O3 models were constructed by means of density functional theory (DFT) and experimental results. The geometrical structures and vibrational frequencies obtained at B3LYP levels of DFT were compared with the corresponding experimental results. EXAFS results suggest silver ion species were predominant on the A...

Accurate description of hydrogen-bonding energies between water molecules and van der Waals interactions between guest molecules and host water cages is crucial for study of methane hydrates (MHs). Using high-level ab initio MP2 and CCSD(T) results as the reference, we carefully assessed the performance of a variety of exchange-correlation functionals and various basis sets in describing the no...

Large-scale density functional theory calculations (DFT) found various types of binding of an unsaturated hydrocarbon (C2H2 and C2H4) to a ZSM-5 zeolite extraframework copper cation. We employed the DFT calculations based on the B3LYP functional to obtain local minima of an unsaturated hydrocarbon adsorbed on one or two copper cations embedded inside ZSM-5, and then compared their stabilization...

Density-functional theory ~DFT! calculations of indirect nuclear magnetic resonance spin–spin coupling tensors J, with the anisotropic but symmetric parts being the particular concern, are carried out for a series of molecules with the linear response ~LR! method. For the first time, the anisotropic components of J are reported for a hybrid functional. Spin–spin tensors calculated using the loc...

In the current investigation, the molecular structure of the anticonvulsant agent (2E)-2-[3-(1H-imidazol-1-yl)-1-phenylpropylidene]-N-phenylhydrazinecarboxamide ((2E)-HIPC) was theoretically modelled using ab initio Hartree-Fock (HF) and density functional theory (DFT/B3LYP) calculations. The Fourier transform (FT) infrared and FT-Raman spectra of (2E)-HIPC were also recorded, and the observed ...

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...