Nanoscale physics

Quantum-chemical calculations of molecules and their clusters – a platform for substantiating the collective properties of fluid vibrations and biological macromolecules
Kornienko N. E. 1, Korniienko A. N. 
1 Taras Shevchenko National University of Kyiv,, Volodymyrska str., 64/3,
 Kyiv-01601, Ukraine.
E-mail: email.of. corresponding_nikkorn@mail.univ.kiev.ua

 Collective (wave) properties of vibrational and electronic states in liquids and especially water have long been discovered by methods of vibrational and nonlinear spectroscopy, but up to the present time they are not taken into account in the existing biochemical concept of the living one. Based on the results of quantum chemical calculations (QCC) of linear СnH2n+2 and cyclic (СH2)n molecules containing a sequence of СН2 groups, as well as water clusters (Н2О)n, the first combination of the series of normal vibrations (NV) of these systems with a given symmetry with the formation of wave vibrational modes νδ  for the valence and deformation vibrations of the СН2 and Н2О groups, as well as the set of low-frequency intermolecular vibrations was first carried out. In this case, the parameter m, numbering the NV, taking into account their shape, corresponds to the wave vector k. Thus, a generalization of the theory of NV systems with repeated structural fragments has been carried out and the existence of a phonon dispersion ν(k) even for individual macromolecules and small clusters of water and a number of molecular liquids has been proved. In this case, the positive dispersion dν/dk>0 of the pendular and fan vibrations of the СН2 groups is combined with the negative dispersion of deformation and valence (symmetric and antisymmetric) vibrations. The phonon branches of low-frequency transverse (ТА1,2), longitudinal (LA) and torsional acoustic vibrations of СnH2n+2 molecules, as well as water clusters, were obtained in a similar manner. It is shown that the widths of the phonon water branches for bulk clusters (Н2О)n are much larger than for the simple cyclic clusters with the same n. The widths of the phonon bands Δν= ν4(k) - ν4 ≈ 20 сm-1 are studied for the mode ν4(Е), the overtone 2ν4 and the series of compound tones of liquid chloroform (СНCl3) and its solutions in CH3ОН from IR absorption and Raman scattering spectra. The interaction between the phonon dispersion ν(k) and the Fermi resonance sequence in liquid С6Н6 is analyzed, which can be the basis for more complex DNA analysis.