Basis sets of atomic orbitals are very efficient for density functional calculations but lack a systematic variational convergence. We present a method to optimize numerical atomic orbitals variationally, using a single parameter to control their range. The efficiency of the basis generation scheme is tested and compared with other schemes for multiple $\zeta$ basis sets. The scheme is shown to be comparable in quality to other widely used schemes albeit offering better performance for linear-scaling computations.

• Received 12 July 2002

DOI:https://doi.org/10.1103/PhysRevB.66.205101