Nonadiabatic Quantum Dynamics in Molecular Systems

Nonadiabatic quantum dynamics examines the coupled evolution of electronic and nuclear degrees of freedom when the Born–Oppenheimer approximation breaks down. In many photophysical and photochemical processes, electronic states become nearly degenerate, giving rise to rapid transitions that are central to energy conversion, molecular recognition and charge transfer. Key features include conical intersections—points of exact degeneracy between potential energy surfaces—that act as ultrafast funnels for electronic relaxation, and nonadiabatic couplings that drive transitions between states. Computational schemes blend quantum mechanical treatment of electrons with classical or semiclassical propagation of nuclei, enabling simulations of excited‐state lifetimes, reaction pathways and coherence phenomena in everything from light‐harvesting complexes to semiconductor quantum dots. An appreciation of nonadiabatic effects is crucial for the design of efficient photovoltaic materials, photoactive biomolecules and quantum devices.

Research from Nature Portfolio

Recent studies have demonstrated how tuning electronic coupling in colloidal quantum dot assemblies can drive a single system from incoherent, nonadiabatic electron transfer to coherent, adiabatic transport. By adjusting inter‐dot neck dimensions and dot sizes, the hybridisation energy is varied, leading to orders‐of‐magnitude changes in transfer rates and illuminating the roles of specific lattice vibrational modes. This work provides a controllable platform to explore fundamental charge‐transfer regimes at elevated temperatures. Another advance utilised extreme‐ultraviolet time‐resolved photoelectron spectroscopy to capture the full multidimensional dynamics of a prototypical diatomic molecule traversing a conical intersection. The high photon energy enabled observation of large‐amplitude motions and branching into photodissociation channels, supported by global potential‐energy‐surface calculations that map the passage from excited‐state wavepacket to ground‐state fragments.

Research from all publishers

A novel mapping approach to surface hopping has been introduced that ensures deterministic electronic transitions by coupling nuclear motion on active potential‐energy surfaces with well‐defined regions of electronic phase space. This method is derived from the quantum‐classical Liouville equation and yields unique prescriptions for momentum rescaling and decoherence corrections, delivering accuracy superior to traditional fewest‐switches surface hopping at comparable computational cost. An established framework for mixed quantum‐classical dynamics has been extended to include arbitrary couplings—such as spin–orbit and light‐matter interactions—by diagonalising a generalised Hamiltonian prior to nuclear propagation. This enables full‐dimensional simulations of internal conversion, intersystem crossing and radiative processes in complex systems including transition‐metal complexes. Finally, a spin‐mapping formulation has been developed for multilevel systems that preserves the underlying SU(N) symmetry, avoids unphysical leakage from electronic subspaces and yields correlation functions through classical trajectories. Benchmarks on light‐harvesting complexes demonstrate significant improvements over conventional Ehrenfest and mapping approaches, bringing high accuracy within reach for large‐scale systems.

Nonadiabatic Quantum Dynamics in Molecular Systems publication trend

The graph below shows the total number of articles in nonadiabatic quantum dynamics in molecular systems across all publications each year (not limited to Nature Index journals).

Technical terms

Born–Oppenheimer approximation: Separation of electronic and nuclear motion under the assumption of much heavier nuclei.

Nonadiabatic coupling: Interaction term that induces transitions between electronic states due to nuclear motion.

Potential energy surface (PES): Multidimensional landscape representing electronic energy as a function of nuclear coordinates.

Conical intersection: Point of degeneracy between two PESs that facilitates ultrafast nonradiative transitions.

Surface hopping: Mixed quantum-classical algorithm in which nuclei move on one PES and stochastically switch between surfaces.

References

1. Incoherent nonadiabatic to coherent adiabatic transition of electron transfer in colloidal quantum dot molecules. Nature Communications (2023).
2. Conical-intersection dynamics and ground-state chemistry probed by extreme-ultraviolet time-resolved photoelectron spectroscopy. Nature Communications (2018).
3. A mapping approach to surface hopping. The Journal of Chemical Physics (2023).
4. Generalized trajectory surface-hopping method for internal conversion and intersystem crossing. The Journal of Chemical Physics (2014).
5. Generalized spin mapping for quantum-classical dynamics. The Journal of Chemical Physics (2020).