In recent year, progress has been made in the study of ballistic heat flow and phonon scattering by phonon spectroscopy and phonon-imaging techniques. Regarding the femtosecond laser application to nanostructures, phonon generation in nanoscale electronics is the focus of interest in the investigation of the mechanism of thermal wave formation at different heating pulses and conditions for heat flux propagation in nanostructures. We test an atomic model of thermal transport in a nanoribbon after a few picosecond pulse heating that leads to the simultaneous presence of two modes, namely, coherent phonons and diffusion, by molecular dynamics (MD) simulation. Our main goal is to investigate the characteristics of the highest magnitude vibrational motion of wave front atoms at different heating pulses and ascertain their correspondence to a single longitudinal optical phonon. To this end it is shown that in the MD model, the equations of heat flux taken through the boundaries of a corresponding sampling area can resolve coherent phonon motion with high resolution when translational and vibrational modes are evaluated separately. Such a definition of heat flux allows the tracing of formation and dynamics of a single phonon. It is applied for different times of heating of a nanoribbon sample. The mechanism underlying the decay of phonons into diffusion is also probed, and energy conversion over the nanoribbon is evaluated. The relevant size of the area for the temporal and spatial flux resolution of a coherent phonon in the MD model is confirmed.

PACS. 21.10 -General and average properties of nuclei; properties of nuclear energy levels. PACS. 21.6OJ -Hartree-Fock and random-phase approximations.Abstract. -In a semi-classical approach to the study of nuclear collective dynamics we analyse the effect of explicit quantum corrections to the Vlasov equation. We show that the lowest multipole response affected is the octupole one. However, quantitatively, these corrections seem to be small for both high-and low-lying octupole states, provided some realistic nuclear potential is used, with surface terms.

Use of solid film nanopore in which DNA is threaded through for efficient DNA sequencing devices has various practical issues concerned with nucleobase motion that should be controlled. Translocation rate and different orientation of nucleobases, stochastic motion of single-strand DNA through a nanopore introduce definite amount of noise into the signal defining interaction of nucleobase and nanopore. We propose to consider the single layer graphene nanopore as a two-way interaction scanning device. The interaction forces between pore and base are structure dependent, even within orientation and noise average over a base, and can be evaluated. The appropriate translocation rate of the base molecule provide a time-dependent function of interaction change inside of interaction interval of each individual base with graphene nanopore. In such case transient characteristics of the individual bases can be used for identification of the bases. The forces between bases and graphene nanopore of 1.5nm diameter are calculated as interaction characteristics of bases. Molecular dynamics method is used for the DNA base and graphene nanopore calculations with the MM2/MM3 potentials for the base and REBO graphene potential. Interaction potential between the bases and graphene are of the MM2/MM3 type although the possibility of the Van der Waals interaction only can also be considered. The noise of the force signal due to orientation of the bases in the pore is evaluated and base-dependent interaction recognition is considered relative to the magnitude of the AFM signal in the non-contact mode. The time-dependent in-plane for graphene transient force signal resolution for different bases is probed. Possibility of base identification by combination of transient in-plane force taken as orientation averaged signal is studied. Obtained results can simultaneously give additional information for the electronic transport calculations with possible transient base orientations relative to the edge of pore in graphene.

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Surface-enhanced Raman scattering (SERS) nanoprobes have shown tremendous potential in in vivo imaging. The development of single oligomer resolution in the SERS promotes experiments on DNA and protein identification using SERS as a nanobiosensor. As Raman scanners rely on a multiple spectrum acquisition, the faster imaging in real-time is required. SERS weak signal requires averaging of the acquired spectra that erases information on conformation and interaction. To build spectral libraries, the simulation of measurement conditions and conformational variations for the nucleotides relative to enhancer nanostructures would be desirable. In the molecular dynamic (MD) model of a sensing system, we simulate vibrational spectra of the cytosine nucleotide in FF2/FF3 potential in the dynamic interaction with the Au20 nanoparticles (NP) (EAM potential). Fourier transfer of the density of states (DOS) was performed to obtain the spectra of bonds in reaction coordinates for nucleotides at a resolution 20 to 40 cm−1. The Au20 was optimized by ab initio DFT GGA and relaxed by MD. The optimal localization of nucleotide vs. NP was defined and spectral modes of both components vs. interaction studied. Bond-dependent spectral maps of nucleotide and NP have shown response to interaction. The marker frequencies of the Au20—nucleotide interaction have been evaluated.