Convergence of the density functional one-centre expansion for the molecular continuum: N-2 and (CH3)(3)N

A large-scale one-centre expansion with a radial B-spline basis set is impl emented for bound and continuum states. A Kohn-Sham hamiltonian is employed with Hartree and exchange-correlation potentials calculated from the SCF e lectron density taken from a previous LCAO calculation. An inverse iteratio n method is used to obtain the continuum wavefunction, from which the cross section and asymmetry parameter are calculated. The convergence with respe ct to angular momentum and cut-off radius is analysed for N-2. The relevanc e of multipolar contributions even at large distances is shown and suggesti ons for further improvements are given. In order to show that the present m ethod is suitable to treat systems of moderate size, the (CH3)(3)N molecule has also been calculated and the results are compared with experiment.