Singlet-triplet crossing

{
  "id": "MLC-T-CHM-010907",
  "term": "Singlet-triplet crossing",
  "field": "Chemistry",
  "definition": "A point or seam in nuclear coordinate space where the potential energy surfaces of a singlet state and a triplet state intersect, so the two states have equal energy at that geometry. Spin-orbit coupling can drive intersystem crossing between the surfaces near such a crossing. Its dimensionality is 3N-7 for N nuclei, one less than the full coordinate space, so a two-coordinate plot shows it as a line.",
  "subject": "Organic and Biomolecular Chemistry",
  "see_also": [
    "branching plane",
    "gradient"
  ],
  "references": [
    "PAC, 2007, 79, 293. 'Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)' on page 421 (https://doi.org/10.1351/pac200779030293)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/singlet-triplet-crossing/"
}