Nonadiabatic coupling

{
  "id": "MLC-T-CHM-008000",
  "term": "Nonadiabatic coupling",
  "field": "Chemistry",
  "definition": "The interaction between different electronic states of a molecular entity that is neglected in the Born-Oppenheimer approximation. This coupling arises from the kinetic energy of the nuclei and causes transitions between potential energy surfaces, meaning the system does not remain in a single electronic state during a chemical process. Nonadiabatic coupling is particularly strong near conical intersections or avoided crossings of potential energy surfaces.",
  "subject": "Physical and Biophysical Chemistry",
  "see_also": [
    "adiabatic",
    "chemical induction",
    "momentum"
  ],
  "references": [
    "PAC, 1996, 68, 149. 'A glossary of terms used in chemical kinetics, including reaction dynamics (IUPAC Recommendations 1996)' on page 175 (https://doi.org/10.1351/pac199668010149)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/nonadiabatic-coupling/"
}