The Hartree-Fock equation is widely accepted as the basic model of electronic structure calculation which serves as a canonical starting point for more sophisticated many-particle models. We have studied the s∗-compressibility for Galerkin discretizations of the Hartree-Fock equation in wavelet bases. Our focus is on the compression of Galerkin matrices from nuclear Coulomb potentials and nonlinear terms in the Fock operator which hitherto has not been discussed in the literature. It can be shown...

The Hartree-Fock equation is widely accepted as the basic model of electronic structure calculation which serves as a canonical starting point for more sophisticated many-particle models. We have studied the s∗-compressibility for Galerkin discretizations of the Hartree-Fock equation in wavelet bases. Our focus is on the compression of Galerkin matrices from nuclear Coulomb potentials and nonlinear terms in the Fock operator which hitherto has not been discussed in the literature. It can be shown...

Extending recent work for the linear Poisson problem for the Laplacian in the framework of Sobolev-Besov spaces on Lipschitz domains by Jerison and Kenig [16], Fabes, Mendez and Mitrea [9], and Mitrea and Taylor [30], here we take up the task of developing a similar sharp theory for semilinear problems of the type Δu - N(x,u) = F(x), equipped with Dirichlet and Neumann boundary conditions.

For $0<p-1<q$ and either $ϵ=1$ or $ϵ=-1$, we prove the existence of solutions of $-{\Delta }_{p}u=ϵu^q$ in a cone $C_S$, with vertex 0 and opening $S$, vanishing on $\partial C_S$, of the form $u\left(x\right)={\left|x\right|}^{-\beta }\omega (x/\left|x\right|)$. The problem reduces to a quasilinear elliptic equation on $S$ and the existence proof is based upon degree theory and homotopy methods. We also obtain a nonexistence result in some critical case by making use of an integral type identity.

Nella prima parte di questa Nota si dimostrano dei risultati di simmetria unidimensionale e radiale per le soluzioni di $\mathrm{\Delta }u+f\left(u\right)=0$ in ${\mathbb{R}}^N$. Questi risultati sono legati a due congetture (De Giorgi, 1978 e Gibbons, 1994) riguardanti la classificazione delle soluzioni dell’equazione $\mathrm{\Delta }u+u\left(1-u^2\right)=0$ in ${\mathbb{R}}^N$. Si dimostra, in particolare, la seguente generalizzazione della congettura di Gibbons: se $N>1$ e se l’insieme degli zeri di $u$ è limitato nella direzione $\nu$, allora $u\left(x\right)=u_0\left(\nu \cdot x\right)$, ovvero, $u$ è unidimensionale. Nella seconda parte si considerano...

Étant donné $L$ un opérateur différentiel d’ordre $m$ sur un ouvert $\Omega$ de ${\mathbf{R}}^N$, $K$ un compact de $\Omega$, $\gamma \&gt;1$ et ${\gamma }^{\text{'}}=\gamma /(\gamma -1)$, nous montrons que toute solution de “$Lu+u^{\gamma }=0$ sur $\Omega \setminus K,u\ge 0$” est solution de “$Lu+u^{\gamma }=0$ sur $\Omega$” dès que la $W^{m,{\gamma }^{\text{'}}}$-capacité de $K$ est nulle. Cette condition s’avère nécessaire quand $L$ est un opérateur elliptique d’ordre 2. Dans ce cas, nous montrons aussi que $``Lu+u|u{|}^{\gamma -1}=\mu ,u{|}_{\partial \Omega }=0^{\text{'}\text{'}}$ où $\mu$ est une mesure de Radon bornée sur $\Omega$, a une solution si et seulement si $\mu$ ne charge pas les ensembles de $W^{2,{\gamma }^{\text{'}}}$-capacité nulle.