A systematic vibrational spectroscopic assignment and analysis of pregabalin has been carried out by using FTIR, FT-Raman spectral data. The vibrational analysis were aided by electronic structure calculations-hybrid density functional methods (B3LYP) performed with 631G(d,p) basis set. Molecular equilibrium geometries, electronic energies, natural bond order analysis, IR intensities, and harmo...

Aromatic groups were incorporated into 9H-9-silafluorene units at the 9-position (mono-9H-silafluorenes) and 9,9'-positions (di-9H-9-silafluorenes). The aryl substituents showed weak conjugation to the 9H-9-silafluorene for 9-aryl substituted ones 1-7 and a 9,9'-phenylene substituted one (compound 8) and they exhibited similar absorption and emission spectra. The 9H-9-silafluorene 10 containing...

We report experimental spectra in the mid-infrared (IR) and near-IR for a series of dibenzoacenes isolated in Ar matrices. The experiments are supported by Density Functional Theory (DFT) and Time-Dependent DFT (TD-DFT) calculations with both vibrational and electronic transitions studied. For the neutrals, we find good agreement between the experimental and B3LYP and BP86 results for all speci...

a Nearly Tridiagonal Matrix Magdy Tawfik Hanna1 ABSTRACT A fully-fledged definition for the fractional discrete Fourier transform of type IV (FDFT-IV) is presented and shown to outperform the simple definition of the FDFT-IV which is proved to be just a linear combination of the signal, its DFT-IV and their flipped versions. This definition heavily depends on the availability of orthonormal eig...

The electronic and optical natures of silica-coated semiconductor nanocrystals (Cd(2)Te(2)@(SiO(2))(24)) have been investigated by density functional theory (DFT) and time-dependent DFT calculations. The calculated results of Cd(2)Te(2)@(SiO(2))(24) have revealed that the structural synergy effect between the Cd(2)Te(2) quantum dots (QDs) and the silica coating shell plays a dominant role in th...

in this paper, using the tight-binding model, we extend the real-space renormalization group method to time-dependent hamiltonians. we drive the time-dependent recursion relations for the renormalized tight-binding hamiltonian by decimating selective sites of lattice iteratively. the formalism is then used for the calculation of the local density of electronic states for a one dimensional quant...

The electronic absorption spectra, ground-state geometries and electronic structures of symmetric and asymmetric squaraine dyes (SQD1-SQD4) were investigated using density functional theory (DFT) and time-dependent (TD-DFT) density functional theory at the B3LYP/6-311++G** level. The calculated ground-state geometries reveal pronounced conjugation in these dyes. Long-range corrected time depend...

The electronic structure and spectra of 3-formylchromone and some of its derivatives are investigated using TD-DFT/B3LYB/6-311G (d, p) level of theory. The results of calculations show that all the studied compounds 1–6 are planar, as indicated from the dihedral angles. The electronic absorption spectra of the studied compounds are recorded in the UV-Vis region, in both ethanol (as polar solven...

We develop and test a method that integrates many-electron weak-field asymptotic theory (ME-WFAT) [Phys. Rev. A 89, 013421 (2014)] in the integral representation (IR) into density functional (DFT) framework. In particular, we present modifications of formula IR ME-WFAT to incorporate potential terms unique DFT. By solving an adiabatic rate equation for angle-resolved ionization yield our DFT-ba...

In this Article, we address the complexity of the emissive processes of a square-planar heteroleptic Pt(II) complex bearing 2-phenylpyridine (ppy) as cyclometalated ligand and an acetylacetonate derivative (dbm) as ancillary ligand. The origins of emission were identified with the help of density functional theory (DFT) and quadratic response (QR) time-dependent (TD)-DFT calculations including ...