Numerical atomic orbitals for linear-scaling calculations

[摘要] The performance of basis sets made of numerical atomic orbitals is explored in density-functional calculations of solids and molecules. With the aim of optimizing basis quality while maintaining strict localization of the orbitals, as needed for linear-scaling calculations, several schemes have been tried. The best performance is obtained for the basis sets generated according to a new scheme presented here, a flexibilization of previous proposals. Strict localization is maintained while ensuring the continuity of the basis-function derivative at the cutoff radius. The basis sets are tested versus converged plane-wave calculations on a significant, variety of systems, including covalent, ionic, and metallic. Satisfactory convergence is obtained for reasonably small basis sizes, with a clear improvement over previous schemes. The transferability of the obtained basis sets is tested in several cases and it is found to be satisfactory as well.

[关键词] DENSITY-FUNCTIONAL CALCULATIONS;ELECTRONIC-STRUCTURE CALCULATIONS;TOTAL-ENERGY CALCULATIONS;PLANE-WAVE CALCULATIONS;AB-INITIO CALCULATIONS;FAST MULTIPOLE METHOD;MOLECULAR-DYNAMICS;TIGHT-BINDING;BASIS-SETS;GAUSSIAN-ORBITALS