Structural, electronic and magnetic properties of ZnS nanotubes (NTs) doped with Mn atoms are studied with first-principles calculations. Formation energies of doped NTs are smaller than that of the pristine, indicating that doing process is an exothermic reaction. Band gaps of doped NTs are narrower than that of the pristine. It indicates that Mn-doped ZnS NTs tends to adopt antiferromagnetic (AFM) configuration. To obtain room temperature ferromagnetism, we replaced a S atom by a C atom. Ferromagnetic (FM) states are lower in energy than AFM states by 0.454 eV. Such energy difference implies that room temperature ferromagnetism can be expected in the system.

Structures and magnetic properties of Cr monodoped and bidoped single-wall ZnS nanotubes are studied with firstprinciples calculations. Formation energies of doped nanotube are lower than those of pristine ones, indicating that doing process is an exothermic reaction. Doped nanotubes have atom-like magnetic moments mainly due to 3d component of Cr atoms. Our results indicate that Cr-doped ZnS nanotubes tends to adopt ferromagnetic (FM) configuration. Energy differences between FM and antiferrimagnetic (AFM) is only 36 meV. To obtain room temperature ferromagnetism, we replace one S atom by C atom. Its FM states are lower in energy than AFM states by 497 meV. Such large energy differences imply that room temperature ferromagnetism could be expected.

A parallel software module of FMM (fast multipole method) for three-dimensional Laplace kernel functions, JASMIN-3DLapFMM, is designed and implemented. The module is based on two phases parallel strategy of both processes and threads. A parallel software module is successfully used to solve the far field potential of electrostatic fields. With a fixed problem size of single processor,almost linear weak parallel scalability is obtained for a grand scale problem with 10¹⁰ particles on more than ten thousand processors. With a fixed size of total problem and 1024 processors, about three times speedup is obtained on four threads.

For parallel computation,two techniques are proposed to couple Fourier transform and fluid dynamics.One is muiti-physics coupled communication technique and the other is parallel Fourier transform.By comparing efficiency of the two techniques,it is shown that the muiti-physics coupled communication technique is better than calling parallel FFTW technique as the number of cores is relatively small,while calling parallel FFTW technique is better as the number of cores is over a thousand.Scalability is demonstrated with a parallel efficiency above 50% on 16 384 processors.Numerical simulation on laser filamentation is shown.

An FFT parallel solver is designed and implemented in JASMIN infrastructure to solve problems,such as computation scale restriction,great change of data structure,different communications among data structures,and arguments' diversity of FFTW functions as using FFTW directly.The solver encapsulates several distributed storages of data,different communications and 1D FFT computations with FFTW.It provides standard functions to users.With this solver FFT parallel computing is realized conveniently.It was used in numerical simulations of laser filament.Scalability was demonstrated with a parallel efficiency above 80% on 2048 processors.

We propose a two-dimensional(2D) monotonicity-and conservation-preserving interpolation operator based on a one-dimensional monotonicity-and conservation-preserving interpolation operator.With several numerical examples we conclude that our interpolation operator is effective.Furthermore,we take it as a refinement interpolation operator in a structured adaptive mesh refinement(SAMR) algorithm to solve numerical examples governed by 2D Euler equation.Results show that our method is effective in SAMR.

We propose a monotonicity- and conservation-preserving interpolation operator, named PQIM. Its order of convergence, conservation-preserving and monotonicity-preserving properties are demonstrated. The interpolation operator is proved to restrain oscillation caused by interpolation effectively.

The governing equations, moving least squares (MLS) interpolant and conservative schemes for moving least squares particle hydrodynamics(MLSPH) are presented. It focuses on numerical evaluatation of area matrix to improve calculation accuracy. Numerical experiments with shock tube and Nob problems are satisfactory. The area matrix is evaluated correctly by a three-order spline integral formula.

The moving least squares particle hydrodynamics (MLSPH) is presented and a 1D MLSPH algorithm is discussed.To reduce oscillations near contact discontinuities,two meshfree Riemann problem initial value methods with different accuracy are introduced.The effect of contact interaction between particles is decreased by the Riemann solver.Efficiency of the method is demonstrated by numerical tests of a 1D shock tube.