实空间高分辨象模拟计算中的动态收敛判据

A DYNAMICAL CONVERGENCE CRITERION FOR THE REAL-SPACE MULTI-SLICE IMAGE SIMULATION METHOD

给出实空间多片层(RSMS)法的动态收敛判据(RSMSD法),利用与晶体结构有关的截断条件,动态地确定了每两片层间传播因子的展开级数,完全克服了RSMS法固有的发散问题。RSMSD法的计算结果与快速傅里叶变换多片层(FFTMS)法的相应结果符合很好,这说明动态收敛判据是正确、有效的。

This paper gives a new dynamical convergence criterion (RSMSD) in the real space multi-slice (RSMS) method, which imposes a practical restriction in choosing dynamically the expan-sion order for the propagator between each pair of slices by using a structure-dependent trun-cation condition, so as to avoid the intrinsic computational divergence problem of the original RSMS method. The validity of the RSMSD method for dynamical diffraction calculation in HREM has been rigorously examined. It has been found that, when the dynamical criterion is satisfied, the RSMSD method gives results in good agreement with those obtained by using fast Fourier transform multi-slice (FFTMS) method but avoiding the computing divergence which can arise in the RSMS method.