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arXiv · 2511.08646

Schr\"{o}dinger equation is $\mathcal{R}$-separable in toroidal coordinates

Matheus E. Pereira·Alexandre G. M. Schmidt
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Abstract

We present, for the first time, exact solutions for the Schr\"{o}dinger equation in Moon and Spencer's toroidal coordinates, and in the electromagnetic toroidal--poloidal coordinate systems. Curiously, both systems present a fractional angular momentum, because of the torus's hole. We achieve these novel solutions using the irregular $\mathcal{R}$-separation of variables, an unexplored approach in Physics, which results in a wavefunction with fractional angular momentum eigenvalues. Numerous solutions for the Schr\"{o}dinger equation in a variety of external potentials are shown, including an external magnetic field. A plane-wave expansion and a Green function are also presented, setting the stage for future progress in this area.

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Matheus E. Pereira, Alexandre G. M. Schmidt. 2025-11-10. Schr\"{o}dinger equation is $\mathcal{R}$-separable in toroidal coordinates. https://arxiv.org/abs/2511.08646

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