Abstract
The B-spline basis is used to calculate for diatomic molecules in DFT. We construct orbital wave functions and density functions by the B-spline. Matrixs constructed by nonrelativistic KS equations and Poisson equations in B-spline are solved as eigenvalue problems, self-consistent iteration. These self-consistent-field calculations with local-densityapproximation(LDA), local-spin-density (LSD) approximation, and generalized gradient expansion(GGA) approximation can obtain good results by using appropriate exchange-correlation approaches. Gunnarsson-Lundqvist(GL) and Ceperley-Alder(CA) exchange-correlation potentials of homogenous electron gases are used for solving KS equation. The generalized gradient expansion(GGA) approximation which considers the gradient expansion of density also be calculated. In this work, calculations within LDA, LSD, and GGA formalism constructed by prolate spheroidal coordinate and B-spline basis are run by programs in C language. The homonuclear diatomic molecule of lithum is calculated, and we attain excellent results. Effects of relativistic and reduced mass do not consider in this work.