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Heinz Siedentop

Publications and source records attributed to Heinz Siedentop.

At least 19 recordsLinked to original sources

Eigenvalue asymptotics of Müller minimizers for atoms and molecules

We study the spectral properties of minimizers of the Müller functional for atoms and molecules with $N$ electrons and total nuclear charge $Z$. We prove that under some suitable assumptions on $Z$ and $N$, the $k$-th eigenvalue of a Müller minimizer $γ_*$ behaves as $A_* k^{-8/3}$ when $k\to \infty$, with a constant $A_*>0$ determined explicitly by the density of $γ_*$. In particular, in the atomic case $V=Z|x|^{-1}$ our assumption holds if $Z$ is sufficiently large and $N\le Z- C_0 Z^{1/3}$. While our proof is inspired by Sobolev's work on the asymptotic behavior of the one-particle density matrix of Schrödinger ground states, the analysis in Müller theory requires several new ingredients concerning both the singular behavior of the integral kernel of the minimizers near the diagonal and the decay properties at infinity.

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Bound on the Excess Charge of Generalized Thomas-Fermi-Weizsäcker Functionals

We bound the number of electrons $Q$ that an atom can bind in excess of neutrality for density functionals generalizing the classical Thomas-Fermi-Weizsäcker functional: instead of the classical power $5/3$ more general powers $p$ are considered. For $3/2<p<2$ we prove the excess charge conjecture, i.e., that $Q$ is uniformly bounded in the atomic number $Z$. The case $p=3/2$ is critical: the behavior changes from a uniform bound in $Z$ to a linear bound at the critical coupling $4\sqrtπ$ of the nonlinear term. We also improve the linear bound for all $p\geq6/5$.

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The Ground State Energy of Heavy Atoms: Leading and Subleading Asymptotics

We study atomic ground state energies for neutral atoms as the nuclear charge $Z$ is large in the no-pair formalism. We show that for a large class of projections defining the underlying Dirac sea -- covering not only the physical reasonable cases but also ``weird'' ones -- the corresponding no-pair ground state energy does not exceed the one of the Furry energy up to subleading order. An essential tool is the use and extension of Séré's results on atomic Dirac-Hartree-Fock theory.

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Relativistic Exchange Bounds

We collect estimates of the exchange energy of the relativistic no-pair Hartree-Fock and Müller functional and use them to show the existence of a minimizer and stability of matter of the relativistic Müller functional in the free picture.

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Equivalence of Sobolev norms involving generalized Hardy operators

We consider the fractional Schrödinger operator with Hardy potential and critical or subcritical coupling constant. This operator generates a natural scale of homogeneous Sobolev spaces which we compare with the ordinary homogeneous Sobolev spaces. As a byproduct, we obtain generalized and reversed Hardy inequalities for this operator. Our results extend those obtained recently for ordinary (non-fractional) Schrödinger operators and have an important application in the treatment of large relativistic atoms.

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The Scott conjecture for large Coulomb systems: a review

We review some older and more recent results concerning the energy and particle distribution in ground states of heavy Coulomb systems. The reviewed results are asymptotic in nature: they describe properties of many-particle systems in the limit of a large number of particles. Particular emphasis is put on models that take relativistic kinematics into account. While non-relativistic models are typically rather well understood, this is generally not the case for relativistic ones and leads to a variety of open questions.

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On the excess charge of a relativistic statistical model of molecules with an inhomogeneity correction

We show that the molecular relativistic Thomas-Fermi-Weizsäcker functional consisting of atoms of atomic numbers $Z_1,...,Z_k$ has a minimizer, if the particle number $N$ is constrained to a number less or equal to the total nuclear charge $Z:=Z_1+...+Z_K$. Moreover, there is no minimizer, if the particle number exceeds $2.56 Z$. This gives lower and upper bounds on the maximal ionization of heavy atoms.

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Relativistic Strong Scott Conjecture: A Short Proof

We consider heavy neutral atoms of atomic number $Z$ modeled with kinetic energy $(c^2p^2+c^4)^{1/2}-c^2$ used already by Chandrasekhar. We study the behavior of the one-particle ground state density on the length scale $Z^{-1}$ in the limit $Z,c\to\infty$ keeping $Z/c$ fixed. We give a short proof of a recent result by the authors and Barry Simon showing the convergence of the density to the relativistic hydrogenic density on this scale.

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Proof of the Strong Scott Conjecture for Chandrasekhar Atoms

We consider a large neutral atom of atomic number $Z$, taking relativistic effects into account by assuming the dispersion relation $\sqrt{c^2p^2+c^4}$. We study the behavior of the one-particle ground state density on the length scale $Z^{-1}$ in the limit $Z,c\to\infty$ keeping $Z/c$ fixed and find that the spherically averaged density as well as all individual angular momentum densities separately converge to the relativistic hydrogenic ones. This proves the generalization of the strong Scott conjecture for relativistic atoms and shows, in particular, that relativistic effects occur close to the nucleus. Along the way we prove upper bounds on the relativistic hydrogenic density.

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The Atomic Density on the Thomas--Fermi Length Scale for the Chandrasekhar Hamiltonian

We consider a large neutral atom of atomic number $Z$, modeled by a pseudo-relativistic Hamiltonian of Chandrasekhar. We study its suitably rescaled one-particle ground state density on the Thomas--Fermi length scale $Z^{-1/3}$. Using an observation by Fefferman and Seco (1989), we find that the density on this scale converges to the minimizer of the Thomas--Fermi functional of hydrogen as $Z\to\infty$ when $Z/c$ is fixed to a value not exceeding $2/π$. This shows that the electron density on the Thomas--Fermi length scale does not exhibit any relativistic effects.

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Accumulation Rate of Bound States of Dipoles in Graphene

We prove that the bound state energies of the two-dimensional massive Dirac operator with dipole type potentials accumulate with exponentials rate at the band edge. In fact we prove a corresponding formula of De Martino et al (2014).

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