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  • Letter
  • Open Access

Small molecule propulsion driven by solvent-mediated ultrafast energy transfer from vibrations to self-translation

Arnau Jurado Romero1,*, Carles Calero2,†, and Rossend Rey1,‡

  • *Contact author: arnau.jurado@upc.edu
  • †Contact author: carles.calero@ub.edu
  • ‡Contact author: rosendo.rey@upc.edu
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Phys. Rev. Research 8, L012060 – Published 10 March, 2026

DOI: https://doi.org/10.1103/w74r-y5fx

Abstract

Despite its interest, self-propulsion at the molecular scale remains an open challenge. In this work, we demonstrate through all-atom molecular dynamics simulations that vibrational excitation of the amphiphilic molecule nitromethane (CH3NO2) in water can lead to transient, directed propulsion. The excess vibrational energy is anisotropically transferred into the solvent, generating a mechanical instability that results in a short-lived net force between the solvent and the molecule. As a consequence, propulsion emerges along the axis of the molecule with speeds of up to 2.2Å/ps, which decay in subpicosecond timescales. Under periodic excitation, this effect is measurable as an enhancement of the translational diffusion coefficient. We show that, despite being sensitive to the solute-solvent interaction model, the propulsion mechanism introduced here is robust to changes in the force field employed to describe atomic interactions. Our findings highlight a propulsion mechanism that is solvent-mediated and externally tunable via vibrational excitation, providing insight into the principles governing active transport at the nanoscale.

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Phys. Rev. Research 8, L012060– Published 10 March, 2026
  • Received 29 July 2025
  • Accepted 12 January 2026
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