Physlib

Physlib.QuantumMechanics.DDimensions.Hydrogen.Basic

Hydrogen atom

This module introduces the `d`-dimensional hydrogen atom with `1/r` potential.

In addition to the dimension `d`, the quantum mechanical system is characterized by a mass `m > 0` and constant `k` appearing in the potential `V = -k/r`. The standard hydrogen atom has `d=3`, `m = mₑmₚ/(mₑ + mₚ) ≈ mₑ` and `k = e²/4πε₀`.

The potential `V = -k/r` is singular at the origin. To address this we define a regularized Hamiltonian in which the potential is replaced by `-k·r(ε)⁻¹`, where `r(ε)² = ‖x‖² + ε²`. This goes by several names including "soft-core" and "truncated" Coulomb potential. e.g. see https://doi.org/10.1103/PhysRevA.80.032507 and https://doi.org/10.1063/1.3290740.

5 declarations

theorem

The mass mm of the hydrogen atom is non-zero.

For a dd-dimensional hydrogen atom system HH with mass mm, it holds that m0m \neq 0.

definition

Regularized Hamiltonian H(ϵ)=12mp2krϵ1\mathbf{H}(\epsilon) = \frac{1}{2m} \mathbf{p}^2 - k \mathbf{r}_\epsilon^{-1}

For a dd-dimensional hydrogen atom characterized by mass mm and a potential constant kk, the regularized Hamiltonian H(ϵ)\mathbf{H}(\epsilon) for a non-zero parameter ϵR×\epsilon \in \mathbb{R}^\times is a continuous linear operator on the Schwartz space S(Rd,C)\mathcal{S}(\mathbb{R}^d, \mathbb{C}) defined as: H(ϵ)=12mp2krϵ1\mathbf{H}(\epsilon) = \frac{1}{2m} \mathbf{p}^2 - k \mathbf{r}_\epsilon^{-1} where p2\mathbf{p}^2 is the momentum-squared operator and rϵ1\mathbf{r}_\epsilon^{-1} is the regularized radius operator that acts via pointwise multiplication by the function x(x2+ϵ2)1/2x \mapsto (\|x\|^2 + \epsilon^2)^{-1/2}.

theorem

The Hydrogen Atom Potential is Almost Everywhere Measurable

For a dd-dimensional hydrogen atom HH characterized by a constant kk, the potential function V(x)=k/xV(x) = -k/\|x\| is almost everywhere measurable.

definition

Continuous linear map of the regularized Hamiltonian H(ϵ)\mathbf{H}(\epsilon)

For a dd-dimensional hydrogen atom characterized by mass mm and potential constant kk, the regularized Hamiltonian H(ϵ)\mathbf{H}(\epsilon) for a non-zero parameter ϵR×\epsilon \in \mathbb{R}^\times is defined as a continuous linear operator on the Schwartz space S(Rd,C)\mathcal{S}(\mathbb{R}^d, \mathbb{C}) such that: H(ϵ)=12mp2kr(ϵ)1\mathbf{H}(\epsilon) = \frac{1}{2m} \mathbf{p}^2 - k \mathbf{r}(\epsilon)^{-1} where p2\mathbf{p}^2 is the momentum-squared operator and r(ϵ)1\mathbf{r}(\epsilon)^{-1} is the regularized radius operator, which acts via pointwise multiplication by the function x(x2+ϵ2)1/2x \mapsto (\|x\|^2 + \epsilon^2)^{-1/2}.

theorem

H(ϵ)=12mp2kr(ϵ)1\mathbf{H}(\epsilon) = \frac{1}{2m} \mathbf{p}^2 - k \mathbf{r}(\epsilon)^{-1}

For a dd-dimensional hydrogen atom HH characterized by mass mm and potential constant kk, the regularized Hamiltonian operator H(ϵ)\mathbf{H}(\epsilon) for any non-zero real parameter ϵR×\epsilon \in \mathbb{R}^\times is given by the expression: H(ϵ)=12mp2kr(ϵ)1\mathbf{H}(\epsilon) = \frac{1}{2m} \mathbf{p}^2 - k \mathbf{r}(\epsilon)^{-1} where p2=pp\mathbf{p}^2 = \mathbf{p} \cdot \mathbf{p} is the momentum-squared operator and r(ϵ)1\mathbf{r}(\epsilon)^{-1} is the regularized inverse radius operator.