Long-Range Interactions in

摘要

The effect of long-range Coulomb interactions on bulk propeerties is studied for the ionic solids NaBr and NaCl.The embedded clustrapproach in the framework of density functional theory is empolyed.The Madelung potential is calculated with the Evjen cube summation method.To exploye the effects of the long-rnage interactions on the electron densities and the Madelung constant,the Evjen cube size is varied from 310 to 19650 point charges for 33 atom clusters.To study the size effect of the quantum region,all-electron clusters with 33 to 87 atoms,embedded in embedded in Evjen cubes of 6859 point charges,are investigated.The results show that for the 81 and 87 aatom clusters the Madelung potential is constant from the center up to the second neighbor shell.For the same atoms,in all clusters,the electron density at the nuclei has nearly the same value.The largest difference found for the positive ions was 0.54%,and for the negative ions,0.14%.