Quantum Dynamics and Nonadiabatic Phenomena

Quantum dynamics explores how quantum systems evolve in time under the influence of electronic and nuclear interactions. While the Born–Oppenheimer approximation treats electronic motion as instantaneous relative to slower nuclear dynamics, nonadiabatic phenomena arise when this separation breaks down. At points of near-degeneracy known as conical intersections or avoided crossings, electronic states exchange population on ultrafast timescales, driving processes in photochemistry, energy transfer and charge separation. Accurate simulation of these events demands methods capable of capturing coupled electron–nuclear motion, such as mixed quantum–classical schemes, multiconfigurational wavepacket propagations and fully quantum approaches. These techniques have advanced understanding of intersystem crossings, vibronic coupling and coherent control of reaction pathways. Beyond molecular chemistry, quantum dynamics informs the design of materials for light harvesting, optoelectronics and quantum information. Ongoing efforts focus on improving computational efficiency, enhancing accuracy in high dimensionality and linking theory with attosecond experiments that resolve electronic motion in real time.

Research from Nature Portfolio

Recent studies have demonstrated coherent control of nuclear motion in molecular cations by tailoring initial electronic wavepackets. Simulations of benzene radical cation dynamics in superpositions of multiple electronic states reveal that nonadiabatic events can occur far from traditional conical intersections and are governed by interference between non-adjacent adiabatic states. This work highlights the possibility of steering fragmentation pathways through bespoke electronic coherence and underscores the role of quantum interference in directing chemical outcomes. Advanced mixed quantum–classical methods were employed to reproduce attosecond pump–probe observations and to propose strategies for selective bond breaking in photochemical applications.

Quantum Dynamics and Nonadiabatic Phenomena publication trend

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

Technical terms

Nonadiabatic transition: A process in which a system moves between electronic states due to coupling with nuclear motion, violating the Born–Oppenheimer separation.

Conical intersection: A point of degeneracy between two electronic potential energy surfaces where their coupling leads to ultrafast population transfer.

Potential energy surface (PES): A multidimensional hypersurface describing the energy of a system as a function of nuclear coordinates for a given electronic state.

Spin-orbit coupling (SOC): An interaction between a particle’s spin and its orbital motion that enables mixing of electronic spin states, crucial for intersystem crossing.

Multiconfigurational Ehrenfest method: A mixed quantum–classical approach that evolves electronic wavepackets and mean nuclear trajectories simultaneously, allowing coherent superpositions.

Multilayer MCTDH (ML-MCTDH): An algorithm that represents many-body wavefunctions via hierarchical tensor networks, enabling accurate quantum dynamics in high dimensions.

References

1. Control of nuclear dynamics in the benzene cation by electronic wavepacket composition. Communications Chemistry (2021).
2. Coherent Mixing of Singlet and Triplet States in Acrolein and Ketene: A Computational Strategy for Simulating the Electron–Nuclear Dynamics of Intersystem Crossing. The Journal of Physical Chemistry Letters (2023).
3. Exploring disordered quantum spin models with a multilayer multiconfigurational approach. Physical Review Research (2023).
4. Ab initio quantum direct dynamics simulations of ultrafast photochemistry with Multiconfigurational Ehrenfest approach. Chemical Physics (2017).