The role of symmetric vibrational modes in the dehoherence of correlation-driven charge migration

TL;DR

This study uses full-dimensional quantum calculations to show that symmetric in-plane vibrational modes primarily cause rapid electronic decoherence in charge migration, lasting only 2-3 femtoseconds after ionization.

Contribution

It identifies the specific vibrational modes responsible for electronic decoherence in charge migration, providing insights for modeling larger systems and designing molecules with longer coherence times.

Findings

Symmetric in-plane vibrational modes cause rapid decoherence.

Electronic coherence lasts only 2-3 femtoseconds.

Other vibrational modes have minimal impact on decoherence.

Abstract

Due to the electron correlation, a fast removal of an electron from a molecule may create a coherent superposition of cationic states and in this way initiate pure electronic dynamics in which the hole-charge left by ionization migrates throughout the system on an ultrashort time scale. The coupling to the nuclear motion introduces a decoherence that eventually traps the charge and a crucial question in the field of attochemistry is how long the electronic coherence lasts and which nuclear degrees of freedom are mostly responsible for the decoherence. Here, we report full-dimensional quantum calculations of the concerted electron-nuclear dynamics following outer-valence ionization of propynamide, which reveal that the pure electronic coherences last only 2-3 fs before being destroyed by the nuclear motion. Our analysis shows that the normal modes that are mostly responsible for the fast electronic decoherence are the symmetric in-plane modes. All other modes have little or no effect on the charge migration. This information can be useful to guide the development of reduced dimensionality models for larger systems or the search of molecules with long coherence times.