Understanding formation mechanism of ZnO diatomic chain and multi-shell structure using physical mechanics:Molecular dynamics and first-principle simulations

In this paper,the possibility of the monatomic chain (MC) formation for ZnO material was studied by molecular dynamics (MD) simulation.The process of MC formation and the effects of temperature,strain rate and size were studied extensively.The tensile process can be divided to be five stages and the ZnO diatomic chain (DC) can be found.The MD results show that most atoms in MC came from the original surface of ZnO nanowires (NWs).Temperature and strain rate are two important factors affecting the process,and both high temperature and low strain rate in a certain range would be beneficial to the formation of DC.Moreover,the effects of strain rate and temperature could attribute to the Arrhenius model and the energy release mechanism.Furthermore,multi-shell structure was found for the samples under tensile strain and the layer-layer distance was about 3.Our studies based on density functional theory showed that the most stable structure of ZnO DC was confirmed to be linear,and the I-V curve was also got using ATK.

Discrete gap breathers in a diatomic K2-K3-K4 chain with cubic nonlinearity

The discrete gap breathers （DGBs） in a one-dimensional diatomic chain with K2-K3-K4 potential are analysed. Using the local anharmonicity approximation, the analytical investigation has been implemented. The dependence of the central amplitude of the discrete gap breathers on the breather frequency and the localization parameter are calculated. With increasing breather frequency, the DGB amplitudes decrease. As a function of the localization parameter, the central amplitude exhibits bistability, corresponding to the two branches of the curve ω = ω（ζ）. With a nonzero cubic term, the HS mode of DGB profiles becomes weaker. With increasing K3, the HS mode of DGB profiles becomes weaker and a bit narrower. For the LS mode, with increasing K3, the central particle amplitude becomes larger, and the DGB profile becomes much sharper. But, as k3 increases further, the central particle amplitude of the LS mode becomes smaller.

Ferroelectricity in a diatomic Ising chain as investigated by the elastic Ising model

An elastic Ising model for a one-dimensional diatomic spin chain is proposed to explain the ferroelectricity induced by the collinear magnetic order with a low-excited energy state. A statistical theory based on this model is developed to calculate the electrical and magnetic properties of Ca3CoMnO6, a typical quasi-one-dimensional diatomic spin chain system. The calculated ferroelectric polarization and dielectric susceptibility show a good agreement with recently reported data on Ca3Co2-xMnxO6 （x ≈ 0.96） （Phys. Rev. Lett. 100 047601 （2008））, although the predicted magnetic susceptibility does not coincide well with experiment. We also address the rationality and deficiency of this model by including a first-order correction which improves the consistency between the model and experiment.

The effect of cubic potentials on discrete breathers in a mixed Klein-Gordon/Fermi-Pasta-Ulam chain

Nonlinearity has a crucial impact on the symmetry properties of dynamical systems. This paper studies a one-dimensional mixed Klein-Gordon/Fermi Pasta-Ulam diatomic chain using the expanded rotating plane-wave approximation and numerical calculations to determine the effect of cubic potentials on the symmetry properties of discrete breathers in this system. The results will be very useful to researchers in the field of numerical calculations on discrete breathers.