The electronic nonadiabatic coupling term: can it be ignored in dynamic calculations?
Related Experiment Video
Updated: Jul 8, 2026

Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids
Published on: May 27, 2020
1Department of Information Technology, University of Debrecen, P.O. Box 12, H-4010 Debrecen, Hungary.
Abstract:
Whereas the search for the degeneracy points which are better known as conical intersections (or ci-points) is usually carried out with a lot of devotion, the nonadiabatic coupling terms (NACTs) which together with the adiabatic potential energy surfaces appear in the nuclear Born-Oppenheimer-Schrodinger equation are ignored in most dynamical calculations. In the present article we consider two well known frameworks, namely, the semiclassical surface hopping method and the vibrational coupling model Hamiltonian that avoid the NACTs and examine to what extent, this procedure is justified.
Related Concept Videos
Debye–Huckel–Onsager Conductance Equation
Reaction Mechanisms: The Steady-State Approximation
Thermodynamic Potentials
Electrostatic Boundary Conditions
The surface integral of an electric field is given by Gauss's law in integral form and is related to...
Adiabatic Processes for an Ideal Gas
Electrostatic Boundary Conditions in Dielectrics
Consider a case where both the mediums across a boundary are two different dielectric materials. Recall that the electric field and electric displacement are proportional and related through the material's permittivity.

