Energy level of a quantum system that corresponds to two or more different measurable states
"Quantum degeneracy" redirects here. For the state of matter, see Degenerate matter. For other uses, see Degeneracy.
In quantum mechanics, an energy level is degenerate if it corresponds to two or more different measurable states of a quantum system. Conversely, two or more different states of a quantum mechanical system are said to be degenerate if they give the same value of energy upon measurement. The number of different states corresponding to a particular energy level is known as the degree of degeneracy (or simply the degeneracy) of the level. It is represented mathematically by the Hamiltonian for the system having more than one linearly independent eigenstate with the same energy eigenvalue.[1]: 48 When this is the case, energy alone is not enough to characterize what state the system is in, and other quantum numbers are needed to characterize the exact state when distinction is desired. In classical mechanics, this can be understood in terms of different possible trajectories corresponding to the same energy.
Degeneracy plays a fundamental role in quantum statistical mechanics. For an N-particle system in three dimensions, a single energy level may correspond to several different wave functions or energy states. These degenerate states at the same level all have an equal probability of being filled. The number of such states gives the degeneracy of a particular energy level.
^Merzbacher, Eugen (1998). Quantum Mechanics (3rd ed.). New York: John Wiley. ISBN 0-471-88702-1.
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with their constituent AO levels. Degenerateenergylevels are commonly shown side by side. Appropriate AO and MO levels are filled with electrons by the...
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the original unperturbed energylevels. Analyzing the curves it becomes evident that even if the original states were degenerate (i.e. E 1 = E 2 {\displaystyle...
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