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In quantum mechanics, a stationary state is an eigenvector of the Hamiltonian, implying the probability density associated with the wavefunction is independent of time.〔Quantum Mechanics Demystified, D. McMahon, Mc Graw Hill (USA), 2006, ISBN 0-07-145546-9〕 This corresponds to a quantum state with a single definite energy (instead of a quantum superposition of different energies). It is also called energy eigenvector, energy eigenstate, energy eigenfunction, or energy eigenket. It is very similar to the concept of atomic orbital and molecular orbital in chemistry, with some slight differences explained below. ==Introduction== A stationary state is called ''stationary'' because the system remains in the same state as time elapses, in every observable way. For a single-particle Hamiltonian, this means that the particle has a constant probability distribution for its position, its velocity, its spin, etc.〔Cohen-Tannoudji, Claude, Bernard Diu, and Franck Laloë. ''Quantum Mechanics: Volume One''. Hermann, 1977. p. 32.〕 (This is true assuming the particle's environment is also static, i.e. the Hamiltonian is unchanging in time.) The wavefunction itself is not stationary: It continually changes its overall complex phase factor, so as to form a standing wave. The oscillation frequency of the standing wave, times Planck's constant, is the energy of the state according to the Planck–Einstein relation. Stationary states are quantum states that are solutions to the time-independent Schrödinger equation: :, where * is a quantum state, which is a stationary state if it satisfies this equation; * is the Hamiltonian operator; * is a real number, and corresponds to the energy eigenvalue of the state . This is an eigenvalue equation: is a linear operator on a vector space, is an eigenvector of , and is its eigenvalue. If a stationary state is plugged into the time-dependent Schrödinger Equation, the result is:〔Quanta: A handbook of concepts, P.W. Atkins, Oxford University Press, 1974, ISBN 0-19-855493-1〕 : Assuming that is time-independent (unchanging in time), this equation holds for any time ''t''. Therefore this is a differential equation describing how varies in time. Its solution is: : Therefore a stationary state is a standing wave that oscillates with an overall complex phase factor, and its oscillation angular frequency is equal to its energy divided by . 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「stationary state」の詳細全文を読む スポンサード リンク
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