Ehrenfest's adiabatic law

Ehrenfest's adiabatic law

[′er·ən‚fests ‚ad·ē·ə¦bad·ik ¦lȯ]
(quantum mechanics)
The law that, if the Hamiltonian of a system undergoes an infinitely slow change, and if the system is initially in an eigenstate of the Hamiltonian, then at the end of the change it will be in the eigenstate of the new Hamiltonian that derives from the original state by continuity, provided certain conditions are met. Also known as Ehrenfest's theorem.
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