Wavelets in all-electron density-functional calculations

We have developed an all-electron density-functional ~AE-DF! program using the Mexican hat wavelet. The AE-DF program is applied to the ab initio all-electron calculations of small molecules as prototype systems, and the construction scheme of multiresolution support spheres is used to optimize the computational efficiency. Convergences are systematically demonstrated as a function of the number of resolution levels and support sphere sizes. Detailed analyses of H2, CO, and H2O molecules and the 1s core-ionized C*O and CO* molecules show good agreement with experiments and other theoretical works. The results indicate that one can gain computational efficiency by several orders of magnitude over the plane-wave-based methods in these molecules. @S0163-1829~99!00827-9#