Best Coapproximation in Normed Linear Spaces.
Best Discrete Mean Rational Approximation.
Best N-term approximation in electronic structure calculations. II. Jastrow factors
We present a novel application of best N-term approximation theory in the framework of electronic structure calculations. The paper focusses on the description of electron correlations within a Jastrow-type ansatz for the wavefunction. As a starting point we discuss certain natural assumptions on the asymptotic behaviour of two-particle correlation functions near electron-electron and electron-nuclear cusps. Based on Nitsche's characterization of best N-term approximation spaces , we prove...
Best N-term approximation in electronic structure calculations I. One-electron reduced density matrix
We discuss best N-term approximation spaces for one-electron wavefunctions and reduced density matrices ρ emerging from Hartree-Fock and density functional theory. The approximation spaces for anisotropic wavelet tensor product bases have been recently characterized by Nitsche in terms of tensor product Besov spaces. We have used the norm equivalence of these spaces to weighted spaces of wavelet coefficients to proof that both and ρ are in for all with . Our proof is based on the...
Best quadrature formula for a certain class of analytic functions
Best Simultaneous Approximation of Bounded Functions with Values in Certain Banach Spaces.
Best simultaneous approximations
In this paper we study simultaneous approximation of real-valued functions in and give a generalization of some related results.
Best Uniform Approximation from a Collection of Subspaces.
Beste Quadraturformeln für Integrale mit einer Gewichtsfunktion.
Bivariate Spline Functions and the Approximation of Linear Functionals.