Conformational, Optoelectronic and Vibrational Properties of the Entacapone Molecule: A Quantum Chemistry Study.

A quantum chemistry study were carried out looking for the conformational, optoelectronic and vibrational properties of the entacapone molecule, an efficient drug used in the Parkinson's disease treatment. Classical annealing was performed to explore the entacapone's molecular configurations, searching for optimal geometries. The quantum optimization calculations were made using three different functional combination levels of the density functional theory (DFT). The structural data (bond length, bond and torsion angles), charge population analysis (absorption spectra) and molecular orbital study (HOMO and LUMO) were obtained considering the lower energy optimized conformation of the entacapone molecule. Furthermore, a complete assignment of the harmonic vibrational frequencies were achieved through their infrared (IR) and Raman spectra.

Classical acoustic waves in damped media.

A Green function technique is employed to investigate the propagation of classical damped acoustic waves in complex media. The calculations are based on the linear response function approach, which is very convenient to deal with this kind of problem. Both the displacement and the gradient displacement Green functions are determined. All deformations in the media are supposed to be negligible, so the motions considered here are purely acoustic waves. The damping term gamma is included in a phenomenological way into the wave vector expression. By using the fluctuation-dissipation theorem, the power spectrum of the acoustic waves is also derived and has interesting properties, the most important of them being a possible relation with the analysis of seismic reflection data.