| Wavelet based multiscale methods provide versatile tools that can be applied in electronic structure calculations in order to obtain methods with optimal computational complexity. Optimality refers to algorithms for which the computational effort scales linear with respect to the number of degrees of freedom of the underlying parametrization of the wavefunction. Rigorous estimates for the error in energy are given for tensor product wavelet bases which have been derived from best N-term approximation theory. We outline such kind of approach for a recently studied perturbation theory of Jastrow type correlated wavefunctions. Essential ingredients are a local description of electron correlations in a hierarchical wavelet basis and efficient techniques for the evaluation of the required two-electron integrals. The resulting Jastrow factors can be further applied in Quantum Monte Carlo calculations. We present some preliminary results for selected model problems. |
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