Partitioning method applied to X-ray absorption near edge structure calculations

So far we have developed an efficient technique to calculate the X-ray absorption near edge structure (XANES) spectra based on partitioning method to include important full multiple scatterings but exclude unimportant scatterings. In this paper we discuss some techniques to obtain rapid convergence of partial summation and give some illustrative examples applied to medium size (about 50) and large clusters (> 100 atoms). The best approach to obtain good convergence to full MS calculation and high efficiency depends on cluster size. Though full MS calculations need much time, that is drastically shortened to less than 10-30% for the large clusters by use of the present methods.