Equations of Electron Dispersion in an E Field

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SUMMARY

The discussion centers on calculating the velocity of an electron in an electric field using the dispersion equation. The group velocity is defined as \( v_g = \frac{1}{\hbar} \frac{dE}{dk} \), which is crucial for determining the electron's behavior under an applied electric field. The participants explore deriving the time dependence of the wave vector \( k \) and the electron's velocity \( v(t) \) and position \( x(t) \) when subjected to an electric field in the -x direction. The complexities of the dispersion relation and the implications of the uncertainty principle are also highlighted.

PREREQUISITES
  • Understanding of quantum mechanics, specifically electron dispersion relations.
  • Familiarity with group velocity and phase velocity concepts.
  • Knowledge of the uncertainty principle in quantum physics.
  • Basic calculus for deriving time-dependent equations.
NEXT STEPS
  • Study the derivation of group velocity in quantum mechanics.
  • Research the implications of the uncertainty principle on electron behavior.
  • Learn about the effects of electric fields on electron motion in solid-state physics.
  • Explore time-dependent Schrödinger equations for particles in electric fields.
USEFUL FOR

Students and researchers in quantum mechanics, particularly those focusing on solid-state physics and electron dynamics in electric fields.

goorioles747
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Homework Statement



Given the dispersion equation of an electron in an electric field:
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Homework Equations



a) calculate the velocity of the electron if k = π/a

b) If the electric field E is applied in the -x direction, derive the time
dependence of k for an electron initially at k = π/a and position x = 0.

c) Derive the time dependence of the electron velocity, v(t), and the
time dependence of the electron position, x(t).

The Attempt at a Solution



for a, do they mean the group velocity which is a function of 1/hbar * dE/dk?
 
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My guess is yes. It makes little sense to just calculate the phase velocity for a single frequency.
 
And would you set the E = .5mv2? Or can you not because of the uncertainty principle?
 
The dispersion isn't quadratic so there is no classical kinetic energy term. I am guessing that you are giving the dispersion for an electron in a crystal. Since you are lacking in details.
 

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