arXiv subjects

Tommi Höynälänmaa

Publications and source records attributed to Tommi Höynälänmaa.

4 recordsLinked to original sources

arXiv2024

Multiresolution Analysis for Compactly Supported Interpolating Tensor Product Wavelets (long version)

We construct multidimensional interpolating tensor product MRA's of the function spaces $C_0(\mathbb{R}^n,K)$, $K = \mathbb{R}$ or $K = \mathbb{C}$, consisting of real or complex valued functions on $\mathbb{R}^n$ vanishing at infinity and the function spaces $C_\textrm{u}(\mathbb{R}^n,K)$ consisting of bounded and uniformly continuous functions on $\mathbb{R}^n$. We also construct an interpolating dual MRA for both of these spaces. The theory of the tensor products of Banach spaces is used. We generalize the Besov space norm equivalence result from Donoho (1992, Interpolating Wavelet Transforms) to our $n$-dimensional construction.

math.FA↗

arXiv2024

Johdatus funktionaalianalyysiin

This book concentrates on functional analysis. The text is written so that it can be followed on the basis of high school mathematics. The book introduces the set theoretical foundations of mathematics, the basic theories of linear algebra and topology, and the theory of topological vector spaces. Distributions, measure theory, and some common spaces of complex-valued functions of real variables are handled, too.

math.HO↗

arXiv2023

Electronic structure calculations with interpolating tensor product wavelet basis

We introduce a basis set consisting of three-dimensional Deslauriers--Dubuc wavelets and solve numerically the Schrödinger equations of H and He atoms and molecules $\mathrm{H}_2$, $\mathrm{H}_2^+$, and $\mathrm{LiH}$ with HF and DFT methods. We also compute the 2s and 2p excited states of hydrogen. The Coulomb singularity at the nucleus is handled by using a pseudopotential. The eigenvalue problem is solved with Arnoldi and Lanczos methods, Poisson equation with GMRES and CGNR methods, and matrix elements are computed using the biorthogonality relations of the interpolating wavelets. Performance is compared with those of CCCBDB and BigDFT.

quant-ph↗

arXiv2022

Electronic Structure Calculation with the Exact Pseudopotential and Interpolating Wavelet Basis

Electronic structure calculations are mostly carried out with Coulomb potential singularity adapted basis sets like STO or contracted GTO. With other basis or for heavy elements the pseudopotentials may appear as a practical alternative. Here, we introduce the exact pseudopotential (EPP) to remove the Coulomb singularity and test it for orbitals of small atoms with the interpolating wave basis set. We apply EPP to the Galerkin method with a basis set consisting of Deslauriers--Dubuc scaling functions on the half-infinite real interval. We demonstrate the EPP--Galerkin method by computing the hydrogen atom 1s, 2s, and 2p orbitals and helium atom configurations $\mathrm{He\;1s^2}$, $\mathrm{He\;1s2s\;{}^1 S}$, and $\mathrm{He\;1s2s\;{}^3 S}$. We compare the method to the ordinary interpolating wavelet Galerkin method (OIW--Galerkin) handling the singularity at the nucleus by excluding the scaling function located at the origin from the basis. We also compare the performance of our approach to that of finite--difference approach, which is another practical method for spherical atoms. We find the accuracy of the EPP--Galerkin method better than both of the above mentioned methods.

physics.chem-ph↗