Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:2501.00010 · Physics-Uspekhi

Coordinate space modification of Fock's theory. Harmonic tensors in the quantum Coulomb problem

Sergei P. Efimov

Published Apr 1, 2021• 2 citations
arXivHTMLPDF

Abstract

We consider Fock's fundamental theory of the hydrogen atom in momentum space which allows a realization of the previously predicted rotation group of a three-dimensional (3D) sphere in four-dimensional (4D) space. We then modify Fock's theory and abandon the momentum space description. To transform and simplify the theory, we use invariant tensor methods of electrostatics in 3D and 4D spaces. We find a coordinate 4D space where the Schrodinger equation becomes the 4D Laplace equation. The transition from harmonic 4D polynomials to original 3D physical space is algebraic and involves derivatives with respect to a coordinate that is interpreted as time. We obtain a differential equation for eigenfunctions in the momentum space and find its solutions. A concise calculation of the quadratic Stark effect is given. The Schwinger resolvent is derived by the method of harmonic polynomials. Vector ladder operators are also considered.

DOI
10.3367/ufne.2021.04.038966

Related papers

Runge-Lenz operator in the momentum space

Sergei P. Efimov

The fundamental quantum Coulomb problem in the momentum space is considered. A differential equation with SO(4) simmetry has been obtained in the momentum space instead of the integral Fock equation. The corresponding equation in the coordinate space is the sum of the squares of the angular momentum and the Runge-Lenz operators.This approach is unknown in the momentum space where the Runge-Lenz operator is not applied in the existing theory. The Runge-Lenz operator obtained in the momentum space is simplier than that in the coordinate space and allows one to effectively consider the Coulomb problem in the momentum space. A relation of new operator to the infinitesimal rotation operator of the three-dimensional the Fock sphere has been determined.

arXiv:2411.14482•Nov 19, 2024•0 citations

Runge–Lenz Operator in the Momentum Space

Sergei P. Efimov

The fundamental quantum Coulomb problem in the momentum space is considered. A differential equation with SO(4) symmetry has been obtained in the momentum space instead of the integral Fock equation. The corresponding equation in the coordinate space is the sum of the squares of the angular momentum and Runge–Lenz operators. This approach is unknown in the momentum space where the Runge–Lenz operator is not applied. The Runge–Lenz operator obtained in the momentum space is simpler than that in the coordinate space and allows one to effectively consider the Coulomb problem in the momentum space. A relation of new operator to the infinitesimal rotation operator of the three-dimensional Fock sphere has been determined.

Письма в Журнал экспериментальной и теоретической физики•May 15, 2023•0 citations

Runge–Lenz Operator in the Momentum Space

Sergei P. Efimov

The fundamental quantum Coulomb problem in the momentum space is considered. A differential equation with SO(4) symmetry has been obtained in the momentum space instead of the integral Fock equation. The corresponding equation in the coordinate space is the sum of the squares of the angular momentum and Runge–Lenz operators. This approach is unknown in the momentum space where the Runge–Lenz operator is not applied. The Runge–Lenz operator obtained in the momentum space is simpler than that in the coordinate space and allows one to effectively consider the Coulomb problem in the momentum space. A relation of new operator to the infinitesimal rotation operator of the three-dimensional Fock sphere has been determined.

Journal of Experimental and Theoretical Physics Letters•May 1, 2023•3 citations

Hydrogen atom as a four-dimensional oscillator

Augustine C. Chen

A coordinate transformation which exhibits the rotational invariance of the hydrogen atom in four-dimensional Hilbert space is introduced. The coordinates are shown to be directly related to the spherical polar and parabolic coordinates in position space. With the use of the transformation, the Schr\"odinger equation for the hydrogen atom left-multiplied by $4r$ is transformed into one for a four-dimensional harmonic oscillator. Solutions are obtained and related to the hydrogenic wave functions. Group-theoretical implications of the transformation and its application to the hydrogen Stark problem are briefly discussed.

Physical Review A•Aug 1, 1980•58 citations

Bound States in Three Dimensions: The Atom

Duncan G. Steel

Abstract In this chapter, we go to three dimensions in space and look at the solution of the time independent Schrödinger equation for the hydrogen atom. The Hamiltonian is then the kinetic energy plus the potential energy due to the Coulomb coupling between the positively charged nucleus and the electron. We construct the angular momentum operator and find that the partial differential equation for the angular momentum eigenfunctions of the spherical coordinates θ,ϕ is the same as the angular part of the ∇2 operator in spherical coordinates. The angular momentum eigenfunctions are the spherical harmonics, with two quantum numbers, l and m, and the solution to the radial part of the Hamiltonian including the Coulomb potential are Laguerre polynomials with one quantum number, called the principle quantum number, n. The hydrogen wave function is the product of a Laguerre polynomial and a spherical harmonic with three quantum numbers. Since these are two- and three-dimensional functions for angular momentum and hydrogen respectively, they are best understood in a series of plots. The chapter concludes by giving the historical letter names to specific orbitals, since they continue to be used today.

•Apr 30, 2021•0 citations

d and f Orbital Shapes as Shadows of 4D Geometry: SO(4) Symmetry, the Fock S³ Mapping, and the Kustaanheimo-Stiefel Transform

Brian Kilgore

A research note connecting the shapes of atomic orbitals to four-dimensional geometry. The hydrogen atom possesses a hidden SO(4) symmetry (Pauli 1926) arising from conservation of the Runge-Lenz vector. In momentum space, hydrogen wavefunctions are exactly the spherical harmonics on the 3-sphere S³ (Fock 1935 stereographic projection). The familiar d and f orbital shapes are therefore 3D equatorial shadows of 4D hyperspherical harmonics. Covers: the Runge-Lenz vector and SO(4) Lie algebra; the Fock stereographic projection theorem; the Kustaanheimo-Stiefel transform (3D hydrogen ≡ 4D harmonic oscillator, exact); the SO(4,2) conformal group encoding the full hydrogen spectrum in a single representation; n-sphere generalization table; and open research directions including an interactive visualization paper (Am. J. Phys. target), angular-momentum dependence of AMEM matrix elements, and lanthanide crystal field analysis in the S³ harmonic basis.

•May 12, 2026•1 citation
We consider Fock's fundamental theory of the hydrogen atom in momentum space which allows a realization of the previously predicted rotation group of a three-dimensional (3D) sphere in four-dimensional (4D) space. We then modify Fock's theory and abandon the momentum space description. To transform and simplify the theory, we use invariant tensor methods of electrostatics in 3D and 4D spaces. We find a coordinate 4D space where the Schrodinger equation becomes the 4D Laplace equation. The transition from harmonic 4D polynomials to original 3D physical space is algebraic and involves derivatives with respect to a coordinate that is interpreted as time. We obtain a differential equation for eigenfunctions in the momentum space and find its solutions. A concise calculation of the quadratic Stark effect is given. The Schwinger resolvent is derived by the method of harmonic polynomials. Vector ladder operators are also considered.
The fundamental quantum Coulomb problem in the momentum space is considered. A differential equation with SO(4) simmetry has been obtained in the momentum space instead of the integral Fock equation. The corresponding equation in the coordinate space is the sum of the squares of the angular momentum and the Runge-Lenz operators.This approach is unknown in the momentum space where the Runge-Lenz operator is not applied in the existing theory. The Runge-Lenz operator obtained in the momentum space is simplier than that in the coordinate space and allows one to effectively consider the Coulomb problem in the momentum space. A relation of new operator to the infinitesimal rotation operator of the three-dimensional the Fock sphere has been determined.
The fundamental quantum Coulomb problem in the momentum space is considered. A differential equation with SO(4) symmetry has been obtained in the momentum space instead of the integral Fock equation. The corresponding equation in the coordinate space is the sum of the squares of the angular momentum and Runge–Lenz operators. This approach is unknown in the momentum space where the Runge–Lenz operator is not applied. The Runge–Lenz operator obtained in the momentum space is simpler than that in the coordinate space and allows one to effectively consider the Coulomb problem in the momentum space. A relation of new operator to the infinitesimal rotation operator of the three-dimensional Fock sphere has been determined.
The fundamental quantum Coulomb problem in the momentum space is considered. A differential equation with SO(4) symmetry has been obtained in the momentum space instead of the integral Fock equation. The corresponding equation in the coordinate space is the sum of the squares of the angular momentum and Runge–Lenz operators. This approach is unknown in the momentum space where the Runge–Lenz operator is not applied. The Runge–Lenz operator obtained in the momentum space is simpler than that in the coordinate space and allows one to effectively consider the Coulomb problem in the momentum space. A relation of new operator to the infinitesimal rotation operator of the three-dimensional Fock sphere has been determined.
A coordinate transformation which exhibits the rotational invariance of the hydrogen atom in four-dimensional Hilbert space is introduced. The coordinates are shown to be directly related to the spherical polar and parabolic coordinates in position space. With the use of the transformation, the Schr\"odinger equation for the hydrogen atom left-multiplied by 4r4r4r is transformed into one for a four-dimensional harmonic oscillator. Solutions are obtained and related to the hydrogenic wave functions. Group-theoretical implications of the transformation and its application to the hydrogen Stark problem are briefly discussed.
Abstract In this chapter, we go to three dimensions in space and look at the solution of the time independent Schrödinger equation for the hydrogen atom. The Hamiltonian is then the kinetic energy plus the potential energy due to the Coulomb coupling between the positively charged nucleus and the electron. We construct the angular momentum operator and find that the partial differential equation for the angular momentum eigenfunctions of the spherical coordinates θ,ϕ is the same as the angular part of the ∇2 operator in spherical coordinates. The angular momentum eigenfunctions are the spherical harmonics, with two quantum numbers, l and m, and the solution to the radial part of the Hamiltonian including the Coulomb potential are Laguerre polynomials with one quantum number, called the principle quantum number, n. The hydrogen wave function is the product of a Laguerre polynomial and a spherical harmonic with three quantum numbers. Since these are two- and three-dimensional functions for angular momentum and hydrogen respectively, they are best understood in a series of plots. The chapter concludes by giving the historical letter names to specific orbitals, since they continue to be used today.
A research note connecting the shapes of atomic orbitals to four-dimensional geometry. The hydrogen atom possesses a hidden SO(4) symmetry (Pauli 1926) arising from conservation of the Runge-Lenz vector. In momentum space, hydrogen wavefunctions are exactly the spherical harmonics on the 3-sphere S³ (Fock 1935 stereographic projection). The familiar d and f orbital shapes are therefore 3D equatorial shadows of 4D hyperspherical harmonics. Covers: the Runge-Lenz vector and SO(4) Lie algebra; the Fock stereographic projection theorem; the Kustaanheimo-Stiefel transform (3D hydrogen ≡ 4D harmonic oscillator, exact); the SO(4,2) conformal group encoding the full hydrogen spectrum in a single representation; n-sphere generalization table; and open research directions including an interactive visualization paper (Am. J. Phys. target), angular-momentum dependence of AMEM matrix elements, and lanthanide crystal field analysis in the S³ harmonic basis.