Adsorption characteristics of magnesium atoms on phosphorus-doped single-walled silicon nanotubes (SWSiNTs) are studied using plane wave pseudopotential method with generalized gradient approximation based on density functional theory. Adsorption energies of magnesium atoms on pure,phosphorus-doped and deformation effects (compressive or tensile) (6,6) SWSiNTs are calculated. Bond and Mulliken population of both pure and phosphorus-doped SWSiNTs are also analyzed.It shows that covalent bond and ionic bond conexist in armchair silicon nanotube superlattices doped with phosphorus atoms by forming ionic bond of Mg-P and Si-P,and enhancing ionic bond of Si-Si. Adsorption energy of Mg atom on SWSiNTs are improved significantly by doping phosphorus atoms. Adsorption energy are also increased under compressive deformation at 0.25%,0.50%,1.00%,1.25% and tensile deformation at 1.00%,1.25%. It enhances adhesion of interface of silicon nanotubes as reinforce combined with matrix.

Lattice dynamics,electronic and lattice contributions to dielectric and piezoelectric responses of BaTiO₃/SrTiO₃(1:1)(BTO/STO 1:1) 10-atom superlattice with Ba/Sr [110] and [111] ordering were investigated with first-principles calculations. We explored ground structure from the highest phase by successively freezing in unstable polar modes. We found that ground structure are in Pm and R3m symmetry,respectively. Lattice contributions to dielectric and piezoelectric tensor coming from individual atoms and individual modes were explored. O and Ti atoms provide extraordinary great contribution to lattice dielectric and piezoelectric responses. On the other hand,great dielectric and piezoelectric tensor are mainly due to low frequency phonons. Especially,for BTO/STO(1:1)superlattice with Ba/Sr [110] ordering,ε₁₁is mainly due to A' phonons with ω_λ=49 cm^-1.

Optical limiting (OL) and dynamical two-photon absorption (TPA) of 4,4'-bis(di-n-butylamino)stilbene (BDBAS) molecules in chirped femtosecond laser pulses are studied by solving Maxwell-Bloch equations with an iterative predictor-corrector finitedifference time-domain (FDTD) method.It shows that both sign and magnitude of chirp rate influence greatly spectrum evolution and OL behavior.Spectra exhibit obvious carrier frequency shifts depending on sign of chirp rate,blue shift for positive chirp rate and red shift for negative chirp rate.As absolute chirp rate increases,shift becomes more obvious,OL window gets narrower and saturation of output intensity becomes greater.Interestingly,self-induced transparency (SIT) appears as a negative chirp rate reduces to a certain value (-0.025 fs^-2).Dynamical TPA cross section is reduced as chirp effect is considered.It provides a method for controlling nonlinear optical absorptions.

Level set and volume of fluid(VOF) methods for incompressible two-phase micro flows considering wall adhesion are presented. In the level set method, based on staggered MAC grid, a second-order projection method is carried out to solve 2D Navier-Stokes(N-S) equations and level set function. In the VOF method, the volume fraction of each phase in each computational cell is employed. Variables and properties of flow are computed to represent volume-averaged values. The interface between fluids is traced with solution of a continuity equation for volume fractions. Computational results are shown and compared with experimental results.

Monte Carlo method is used to simulate such a complete course, in which the ions pass through the neutral region, the sheath, and the shield region of a virtual cathode formed by secondary electrons near the workpiece surface, finally come to be absorbed by the surface of the workpiece with negative bias in ECR microwave plasma.Discussion covers the connection problem of neutral region and sheath at the sheath edge.The non linear Poisson equation is solved with "trial" method, and results in smooth and self consistent spectrum of potential and distributions of ion energy and angle at the surface of workpiece.

In plasma source ion implantation (PSⅡ), the target immersed directly in a uniform Plasma is biased with high negative voltage pulse.Soaexpanding plasma sheath forms between the plasma and the surface of solid material and implant ions into the target. A numerical simulation model in one-dimensional planar geometry is developed to determine the temporal and spatial evolution of the sheath for the voltage pulse of rectangular and trapezoidal wave forms. Especially, the sheath evolution is simulated at the fall time of a trapezoidal voltage pulse.By numerical results the forcing of the presheath exhibits to be related to the pulse length and the applied voltage.

The critical and oscillating appearances ane the break of the integral limit which are encountered in the numeral calculation of the cross section are described and treated overally. The cross sections, collision integrals, and transport coefficients of noble-gases are calculated, according to the interactions of noblegas atoms by our method. The transport coefficients are compared with the experimental