Physical Meaning of Neumann and Robin Boundary Conditions for the Schrödinger Equation

Fuente: arXiv
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Autore principale: Tumulka, Roderich
Natura: Preprint
Pubblicazione: 2023
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author Tumulka, Roderich
author_facet Tumulka, Roderich
contents The non-relativistic Schrödinger equation on a domain $Ω\subset \mathbb{R}^d$ with boundary is often considered with homogeneous Dirichlet boundary conditions ($ψ(x)=0$ for $x$ on the boundary), homogeneous Neumann boundary conditions ($\partial_n ψ(x)=0$ for $x$ on the boundary and $\partial_n$ the normal derivative), or Robin boundary conditions ($\partial_nψ(x)=αψ(x)$ for $x$ on the boundary and $α$ a real parameter). Physically, the Dirichlet condition applies if the potential is much higher outside than inside the domain (``potential well''). We ask, when does the Neumann or Robin condition apply physically? Our answer is, when the potential is much lower (at the appropriate level) in a thin layer along the surface of a potential well, or when a negative delta potential of the appropriate strength is added at a surface close to the surface of the potential well.
format Preprint
id arxiv_https___arxiv_org_abs_2309_15835
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Physical Meaning of Neumann and Robin Boundary Conditions for the Schrödinger Equation
Tumulka, Roderich
Quantum Physics
Analysis of PDEs
The non-relativistic Schrödinger equation on a domain $Ω\subset \mathbb{R}^d$ with boundary is often considered with homogeneous Dirichlet boundary conditions ($ψ(x)=0$ for $x$ on the boundary), homogeneous Neumann boundary conditions ($\partial_n ψ(x)=0$ for $x$ on the boundary and $\partial_n$ the normal derivative), or Robin boundary conditions ($\partial_nψ(x)=αψ(x)$ for $x$ on the boundary and $α$ a real parameter). Physically, the Dirichlet condition applies if the potential is much higher outside than inside the domain (``potential well''). We ask, when does the Neumann or Robin condition apply physically? Our answer is, when the potential is much lower (at the appropriate level) in a thin layer along the surface of a potential well, or when a negative delta potential of the appropriate strength is added at a surface close to the surface of the potential well.
title Physical Meaning of Neumann and Robin Boundary Conditions for the Schrödinger Equation
topic Quantum Physics
Analysis of PDEs
url https://arxiv.org/abs/2309.15835