Triple

Target class: LS coupling
Context triple: [Russell–Saunders coupling, instanceOf, LS coupling]

• A. Einstein coefficient
  The Einstein coefficient is a parameter in quantum theory that quantifies the probability per unit time of spontaneous or stimulated emission or absorption of radiation by an atom or molecule transitioning between energy levels.
• B. screened Coulomb potential
  A screened Coulomb potential is a modified Coulomb interaction where the effective charge is reduced with distance, typically modeled by an exponential decay factor that accounts for the presence of a medium or charge carriers that shield the interaction.
• C. Casimir operator
  The Casimir operator is a distinguished element of the center of the universal enveloping algebra of a Lie algebra (or Lie group) that commutes with all generators and acts as a scalar on each irreducible representation, thereby classifying those representations.
• D. atomic system
  An atomic system is a conceptual model representing one or more atoms and their interactions, including their structure, energy states, and behavior under physical laws.
• E. central potential
  A central potential is a scalar potential energy function that depends only on the distance from a fixed point (usually the origin), leading to spherically symmetric forces directed along the line connecting a particle to that point.
• F. None of above. chosen