Energy levels and oscillator strengths of Si¹¹⁺ are computed by using CI code CIV3.In the calculation all configuration interactions are taken into account for the various configurations formed by keeping one electron on 1s orbital and populating the two other electrons on the rest orbitals.It is shown that the oscillator strengths computed in such a way are much improved.

2-order norm-preserving and symplectic scheme and 2-order explicit symplectic scheme for separable and linear Hamiltonian system including explicitly time are constituted and applied to compute interaction of the simulated laser field with an electron in the finite width and infinite depth potential well,the results are in good agreement with theoretical analysis.

The scheme-conservation quantities of the 1-and 2-order explicit symplectic schemes are found according to the quadric-form conservation quantities for Separable and linear Hamiltonian Systems.It can be shown that so long as the time-step is properly small the norm and the energy can keep conservied in certain accuracy.

A simple example is computed by using R-K approach and step-by-step normalization correction.It is shown that the norm of wave function can be preserved by using this method,However,other physical quantities,such as energy of the system and population probabilities on the states,are still not reasonable,even worse.

By using Coulomb-Born-exchange approximation and Zscaled hydrogenic approximation the excitation cross sections and rate coefficients between fine-structure levels of Mn²²⁺ in water window are calculated.In order to take the correlation effects and relativistic effects into account more effectively, the effective nuclear charges are modified in the computation.

A computational code JLULP1 of plasma produced by laser irradiating rectangular target written by us is reported. By using this code, the spatial distrubutional and time-dependent properties of plasma produced by laser irradiating rectangular Sitarget, and the relations of plasma properties with shapes of target have been investigated for the first time. Comparison with the plasma produced by cylindrical target shows that the plasma produced by rectangular target favours three-body recombination.