Complete Set of Hydrogen Atoms Eigenfunctions in Momentum Represesentation

Peter D. Robinson

The orthogonality requirement usually specified for the eigenfunctions φ of a quantum-mechanical operator P which has a continuous spectrum of eigenvalues λ, is ∫φ*(λ)φ(λ′) dλ=δ(λ−λ′). The derivation of this result is examined; it is seen to be merely a sufficient, but not a necessary condition for the consistent expansion of a bound-state wavefunction ψ in the form ∫ a(λ)φ(λ) dλ. The situation when P is a generalized momentum operator is investigated in detail. Such operators were discussed in the preceding paper. It is shown that any two of the corresponding momentum eigenfunctions are not usually orthogonal. Nevertheless, with the help of Fourier analysis, a consistent expansion ψ=∫ a(λ)φ(λ) dλ is established. The theory is illustrated with the familiar examples of a ``particle in a box'' and a ground-state hydrogen atom. When a space coordinate has a finite range, a quantum condition can be imposed on the generalized momentum eigenvalues so that the momentum eigenfunctions form a complete discrete orthogonal set. We attempt to justify the belief that such quantization is not essential unless it is necessary to ensure single-valued eigenfunctions.

S. Rajasekar, R. Velusamy

This chapter discusses the momentum eigenfunctions and momentum probability distribution for some simple time-independent quantum systems. The position-space distribution is useful when we perform measurements of position of a particle. Photo-cells and photographic plates are useful for position measurements for photons. The momentum representation is helpful in the case of measurement of momentum of a particle. The momentum representation is completely equivalent to the coordinate representation. In spite of their complete equivalence, the momentum representation could throw much insight on certain features that may remain hidden in the coordinate representation. A method using delta function interactions has been introduced for constructing momentum wave function for hydrogen atom and hydrogen molecule ion. Momentum space is shown to be better suited for exploring electronic wave functions of quasiperiodic systems.

Xinghua Li, Yang Ya-tian, 福建师范大学物理与光电信息科技学院,福州 350007

The eigenfunction of hydrogen atom is expressed in a unified way with four boson operators and Bogoliubov transformation, and the corresponding relations with t he wave function expressed in spherical coordinates is given as well. The proble m of operator expressions of hydrogen atoms is solved completely.

Brian P. Anderson