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Is the energy inside an electron-orbital vibrational energy?

  1. Jun 20, 2015 #1
    Is the kinetic and potential energy inside an electron (orbital) of an atom referred to as vibrational energy? Or just electrical?

    And would each orbital be vibrating at a particular frequency -- an EM frequency?
  2. jcsd
  3. Jun 20, 2015 #2


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    No, there is nothing vibrational about it. You cannot have a classical view of what goes on at the atomic level, it is described by quantum mechanics. There is a frequency associated to the orbitals, but it is a frequency related to the Schrödinger equation and not to a classical vibration.
  4. Jun 20, 2015 #3
    So the kinetic energy in each orbital of an atom is not vibrational energy, therefore doesn't contribute to the vibration of an orbital?

    Then is there a quantum energy that is vibrational and within each orbital?

    Does the orbital have a quantum vibration (like that of a standing wave)? Is that what you were alluding to when you were speaking of a frequency (of a non-classical type) associated to an orbital?

    I've heard it said that an electron is described by a probabilistic quantum wavefunction, which spreads out through space and vibrates. Is this correct?

    There would be a quantum vibrational frequency for each orbital within an atom?
    Last edited: Jun 20, 2015
  5. Jun 22, 2015 #4


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    The first part is true, the last is not true in all cases. Observation of quantity in QM is usually characterized by the mean value of the operator associated to that quantity. If the atom is in one of its Hamiltonian's eigenstate, let's say ##|a\rangle## (which is called the stationary state), the mean value of any observables including position is time independent: ##\langle a | U^\dagger r U| a \rangle = e^{i(E_a-E_a)t/\hbar} \langle a | r | a \rangle = \langle a | r | a \rangle##, i.e. there is no change of the most probable position to find an electron in time possible. This mean value may depend on time if the atom is in a superposition state.

    There does exist vibrational degree of freedom in molecules but not in atoms.
    Last edited: Jun 22, 2015
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