Molecular dissociation in presence of catalysts: Interpreting bond breaking as a quantum dynamical phase transition

TL;DR

This paper models molecular bond formation and dissociation in the presence of metal catalysts as a Quantum Dynamical Phase Transition, revealing sudden changes in observables linked to non-Hermitian Hamiltonians and resonances within the d-band spectrum.

Contribution

It introduces a novel quantum dynamical framework for understanding catalytic bond breaking as a phase transition involving non-Hermitian Hamiltonians.

Findings

Bonding and antibonding orbitals undergo smooth crossovers near the surface.

Resonances within the d-band spectrum move and collapse into metallic resonances.

The model aligns with DFT predictions of sudden observable jumps during dissociation.

Abstract

In this work we show that the molecular chemical bond formation and dissociation in presence of the d-band of a metal catalyst can be described as a Quantum Dynamical Phase Transition (QDPT). This agree with DFT calculations that predict sudden jumps in some observables as the molecule breaks. According to our model this phenomenon emerges because the catalyst provides for a non- Hermitian Hamiltonian. We show that when the molecule approaches the surface, as occurs in the Heyrovsky reaction of H 2, the bonding H 2 orbital has a smooth crossover into a bonding molecular orbital built with the closest H orbital and the surface metal d-states. The same occurs for the antibonding state. Meanwhile, two resonances appear within the continuous spectrum of the d- band which are associated with bonding and antibonding orbitals between the furthest H atom and the d-states at the second metallic layer. These move towards the band center where they collapse into a pure metallic resonance and an almost isolated H orbital. This phenomenon constitutes a striking example of the non-trivial physics enabled when one deals with non-Hermitian Hamiltonian beyond the usual wide band approximation.