We present a study of the electronic and optical properties of a series of alkali halide crystals AX, with A = Li, Na, K, Rb and X = F, Cl, Br based on a recent implementation of hybrid-exchange time-dependent density functional theory (TD-DFT) (TD-B3LYP) in the all-electron Gaussian basis set code CRYSTAL. We examine, in particular, the impact of basis set size and quality on the prediction of...

The synthesis and characterization of different ether and ester derivatives of 8-hydroxyquinoline have been made. UV-visible and fluorescence spectra of these compounds have revealed spectral dependence on both solvent and O-substituent. The fluorescence intensity of ether derivatives revealed higher intensity for 8-octyloxyquinoline compared with 8-methoxyquinoline, whereas those of ester deri...

Hydrogen atom transfer is one important reaction in biological system, industry, and atmosphere. The preluded by hydrogen bond dissociation. To gain a comprehensive understanding on the reaction, it necessary to investigate how current computational methods model As starting point, we utilized density functional theory-based calculations identify effect of dispersion long-range corrections O—H ...

Two combined quantum mechanics/molecular mechanics (QM/MM) molecular dynamics simulations, namely, HF/MM and B3LYP/MM, have been performed to investigate the local structure and dynamics of liquid ammonia. The most interesting region, a sphere containing a central reference molecule and all its nearest surrounding molecules (first coordination shell), was treated by the Hartree-Fock (HF) and hy...

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...

The GW approximation is nowadays being used to obtain accurate quasiparticle energies of atoms and molecules. In practice, the GW approximation is generally evaluated perturbatively, based on a prior self-consistent calculation within a simpler approximation. The final result thus depends on the choice of the self-consistent mean-field chosen as a starting point. Using a recently developed GW c...

The ground and excited state geometries, the excitation and emission energies for a series of fluorescein derivatives in aqueous solutions have been investigated using time-dependent density functional theory (TD-DFT) with B3LYP and a long-range corrected CAM-B3LYP functional. The RI-CC2 method was employed to confirm the CAM-B3LYP results. As far as we know, the excited state geometries for a ...

The energetics of the Menshutkin-like reaction between four mesylate derivatives and ammonia have been computed using B3LYP functional with the 6-31+G** basis set. Additionally, MPW1K/6-31+G** level calculations were carried out to estimate activation barrier heights in the gas phase. Solvent effect corrections were computed using PCM/B3LYP/6-31+G** level. The conversion of the reactant complex...

Conformational analyses on 2-substituted (methoxy, vinyloxy, and acetoxy) methylenecyclohexanes have been performed computationally with HF, B3LYP, PBE0, and MP2 and the 6-31G(d) basis set. The global minimum for the methoxy substituent is an axial conformer. For the vinyloxy substituent, except with PBE0, an axial conformer is determined as the global minimum. The acetoxy substituent prefers t...

BiNi clusters have been studied using the hybrid B3LYP density functional and diffusion quantum Monte Carlo (DMC) methods. Different cluster families have been characterized for each cluster size using B3LYP, and the energy differences have been compared with those obtained within DMC. The DMC results predict that the global minimum energy structures are rings for i ) 2-9, a three-ring structur...