Quantum Mechanics of Particles Constrained to Spiral Curves with Application to Polyene Chains

TL;DR

This paper develops a quantum mechanical model for particles constrained to spiral curves, applying it to polyene chains, and derives analytical solutions that match experimental data on electronic transitions.

Contribution

It introduces two approaches to model $ ext{π}$ electrons on spiral curves, providing analytical solutions and insights into polyene electronic transitions.

Findings

Analytical solutions for Schrödinger equation on spiral curves using Bessel functions.

Good agreement with experimental data on $ ext{π}$-$ ext{π}^*$ transitions.

Effective mass corrections improve the particle-in-a-box model accuracy.

Abstract

Context: Due to advances in synthesizing lower dimensional materials there is the challenge of finding the wave equation that effectively describes quantum particles moving on 1D and 2D domains. Jensen and Koppe and Da Costa independently introduced a confining potential formalism showing that the effective constrained dynamics is subjected to a scalar geometry-induced potential; for the confinement to a curve, the potential depends on the curve's curvature function. Method: To characterize the $\pi$ electrons in polyenes, we follow two approaches. First, we utilize a weakened Coulomb potential associated with a spiral curve. The solution to the Schr\"{o}dinger equation with Dirichlet boundary conditions yields Bessel functions, and the spectrum is obtained analytically. We employ the particle-in-a-box model in the second approach, incorporating effective mass corrections. The $\pi$-$\pi^*$ transitions of polyenes were calculated in good experimental agreement with both approaches, although with different wave functions.