Theoretical and mathematical physics

Modeling of Vibrational Spectra of L-tryptophan in Condensed States

Background and Objectives: This work is devoted to the interpretation of IR and Raman spectra of Trp in the condensed states. For this purpose, we calculated the complexes in the zwitterionic form of Trp with the water molecules. Obtained results allow us to determine the influence of hydrogen bonds on the vibrational spectra of Trp in the aqueous solution and solid state.

IR Spectra of Triphenyl Phosphite and Their Interpretation by Molecular Modeling

Background and Objectives: IR spectra of triphenyl phosphite (TPhPh) were measured in liquid (at 320 K), glassy and glacial phases and in hexagonal (metastable) and monoclinic (stable) crystal phases at 12 K. The observed differences in the spectra is a consequence of the implementation of the conformers of different types in the sample. To substantiate this hypothesis, structurally dynamic models of the three most probable conformers (I –III) were built. The conformers are different in angles of rotation of the phenyl rings around the C-O bonds.

AD HOC Quantization of the Electromagnetic Momentum for a Dispersive Medium

 There are two types of linear field momentum in the macroscopic electrodynamics: Minkowski momentum, and Abraham momentum. The first is conserved inside the uniform substance, the second is included into the momentum balance in relation to the center of energy. These two quantities must comply with two measures of photon momentum. Unfortunately, the ad hoc quantization of the Minkowski momentum in dispersive medium leads to the theoretical photon momentum, which differs from the observed momentum.

Molecular Modeling and Vibrational Spectra of 4,4,’-clorobenzophenone

Vibrational infrared and Raman spectra of 4,4’-chlorobenzophenone have been measured at room temperature in the ranges 400–3200 and 0–3200 cm−1 respectively. Modeling of structure and vibrational spectra has been performed by a density functional theory method B3LYP/6-31+g(d) and 6-31-g(d). Energy, structure, components of the dipole moment and polarizability tensor, force constants, frequencies of normal modes in harmonic approximation and their intensities in the IR and Raman activity have been calculated. Interpretation of measured spectra is given.