Related Experiment Video
Updated: Apr 19, 2026

Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids
Published on: May 27, 2020
First order nonadiabatic coupling matrix elements between excited states: implementation and application at the
Zhendong Li1, Bingbing Suo1, Wenjian Liu1
1Beijing National Laboratory for Molecular Sciences, Institute of Theoretical and Computational Chemistry, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistryand Molecular Engineering, and Center for Computational Science and Engineering, Peking University, Beijing 100871, People's Republic of China.
This study details the rigorous theory of first-order nonadiabatic coupling matrix elements (fo-NACME) for excited states using time-dependent density functional theory and Tamm-Dancoff approximation. The methods enable efficient computation for large molecules, aiding nonadiabatic dynamics research.
Area of Science:
- Computational Chemistry
- Theoretical Chemistry
- Quantum Chemistry
Background:
- Nonadiabatic coupling matrix elements (NACME) are crucial for understanding excited-state dynamics.
- Previous theoretical frameworks for NACME were abstract and computationally intensive.
Purpose of the Study:
- To specify the first-order nonadiabatic coupling matrix elements (fo-NACME) theory for practical computational models.
- To enable efficient calculation of fo-NACME for large molecular systems.
Main Methods:
- Implementation of fo-NACME using a Lagrangian formalism.
- Development of atomic-orbital based direct algorithms for fo-NACME computation.
- Application to time-dependent density functional theory and particle-particle Tamm-Dancoff approximation models.
Main Results:
- The computation of fo-NACME is demonstrated to be similar to excited-state gradient calculations.
- Prototypical systems were used to illustrate the conceptual aspects of the implemented methods.
Conclusions:
- The developed methods provide a computationally feasible approach for calculating fo-NACME.
- These advancements hold significant potential for studying internal conversions and nonadiabatic dynamics in large molecules.
More Related Videos
Related Concept Videos
Double Resonance Techniques: Overview
Spin decoupling is usually achieved by...
NMR Spectroscopy: Spin–Spin Coupling
¹H NMR: Interpreting Distorted and Overlapping Signals
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are...
Spin–Spin Coupling: Three-Bond Coupling (Vicinal Coupling)
The extent of coupling depends on the C‑C bond length, the two H‑C‑C angles, any electron-withdrawing substituents, and the dihedral angle between the...
¹H NMR Signal Multiplicity: Splitting Patterns
¹H NMR: Long-Range Coupling
In alkenes, spin information is communicated via σ–π overlap, as seen in allylic (four-bond) and homoallylic (five-bond) couplings. These coupling interactions are stronger when the σ bond is parallel to the alkene...

