Modern Physics Letters B

The phase stability and site preference of some ternary elements of ThMn₁₂ type rare-earth intermetallic compounds R(Co,T)₁₂ and R(Co,T)₁₂N_x are evaluated based on ab initio converted interatomic potentials. The calculated results show that adding either Mo or Mn makes the crystal cohesive energy decrease markedly. It proved that these elements can stabilize R(Co,T)₁₂ with ThMn₁₂ structure. The systemic energy is the lowest when T atoms occupy symmetrically 8i sites. For T=Mo or Mn, the doped nitrogen atom does not affect the order of site preference of these stabilizing elements. Moreover, the nitrogen atom occupies 2b sites. According to the calculated results, it can be seen that lattice parameters and X-rays are in good agreement with experiment. All the above results indicate that the ab initio converted pair potentials are effective for the calculation of these kinds of anisotropy materials and some related nitrides.

A variational method is used to investigate the binding energies of bound polarons near the interface in a GaAs/Al_xGa_1-xAs heterojunction by considering the hydrostatic pressure effect. It is found that the comprehensive pressure effect on the heterojunction factors increases the binding energies near linearly. The pressure influence on the binding energy for the impurity located on the channel side is stronger than that for the impurity located on the barrier side. The pressure effect is more obvious when the impurity is located on the channel side and is not so far from the interface. The pressure influences on the longitudinal optical phonons and interface optical phonons are discussed.

We first reobtain in a simpler way the Haldane fractional statistics at thermal equilibrium. We then show that the mean occupation number for fractional statistics is invariant to a group of duality transformations, a non-abelian subgroup of a fractional linear group.

We consider stochastic second-order partial differential equations. We indroduce a noisy non-linear wave equation and discuss its connections, in particular via the Lorentz transformation, with known stochastic models.

By using micron size permanent magnets we have trapped directly single diamagnetic micron size polystyrene microspheres inside a buffer solution with a magnetic field and demonstrated self-assembly of several hundred microns long chains of microspheres in magnetic traps.

For linearly coupled double-well oscillators the regularity–partial chaos–regularity transition is found. First, an incomplete KAM scenario develops with increasing energy, from integrable pattern comprising in-phase and out-of-phase small elliptic orbits towards a partial chaos, with a deformed regular island immersed in a chaotic sea. At a critical energy a new deformed island appears as a mirror image. Above the critical energy the inverse KAM scenario leads to gradual destruction of partial chaos and to the appearance of large elliptic orbits which correspond to the large-amplitude limit governed by uncoupled oscillators with cubic anharmonicities.