Eliashberg theory

Target entity: Eliashberg theory
Context triple: [BCS theory of superconductivity, relatedTo, Eliashberg theory]

• A. BCS theory of superconductivity
  The BCS theory of superconductivity is a fundamental microscopic theory that explains superconductivity through the formation of Cooper pairs of electrons and their collective quantum behavior in a solid.
• B. Feynman–Hellmann theorem
  The Feynman–Hellmann theorem is a result in quantum mechanics that relates the derivative of an energy eigenvalue with respect to a parameter in the Hamiltonian to the expectation value of the corresponding derivative of the Hamiltonian.
• C. Rayleigh–Schrödinger perturbation theory
  Rayleigh–Schrödinger perturbation theory is a fundamental method in quantum mechanics for approximating the energies and states of a system by treating interactions as small corrections to an exactly solvable problem.
• D. Fokker–Planck equation
  The Fokker–Planck equation is a partial differential equation that describes the time evolution of the probability density function of a stochastic (random) process, such as Brownian motion.
• E. Einstein–Smoluchowski relation
  The Einstein–Smoluchowski relation is a fundamental equation in statistical physics that links the diffusion coefficient of particles undergoing Brownian motion to their mobility and thermal energy.
• F. None of above. chosen
• G. Unsure - the case is ambiguous/there is not enough information to decide.

Target entity: Eliashberg theory
Target entity description: Eliashberg theory is an extension of BCS superconductivity that incorporates strong-coupling and frequency-dependent effects to more accurately describe real superconducting materials.

• A. BCS theory of superconductivity
  The BCS theory of superconductivity is a fundamental microscopic theory that explains superconductivity through the formation of Cooper pairs of electrons and their collective quantum behavior in a solid.
• B. London equations
  The London equations are fundamental relations in superconductivity that describe how magnetic fields behave inside superconductors, capturing key features like the Meissner effect and zero electrical resistance.
• C. Fermi surface
  The Fermi surface is the boundary in momentum space separating occupied from unoccupied electron states at zero temperature, crucial for determining a metal’s electronic and superconducting properties.
• D. Meissner effect
  The Meissner effect is the phenomenon in which a superconductor expels magnetic fields from its interior when cooled below its critical temperature, leading to perfect diamagnetism.
• E. Feynman–Hellmann theorem
  The Feynman–Hellmann theorem is a result in quantum mechanics that relates the derivative of an energy eigenvalue with respect to a parameter in the Hamiltonian to the expectation value of the corresponding derivative of the Hamiltonian.
• F. None of above. chosen