For copper's chain ( , )

PHYSICS · Multi-part · Fermi University Physics · Condensed Matter, Materials & Soft Matter · Lattice dynamics and thermal properties of solids · Lattice dynamics and thermal properties of solids

Condensed Matter Physics, Ch Elastic waves and the vibrating chain

Problem

For copper's chain (

v_s=4760\,\mathrm{m\,s^{-1}}

a=2.556\,\mathrm{\mathring{A}}

), compute the phase velocity

\omega/q

and the group velocity

v_g

at ((a))

q=\pi/(3a)

and ((b))

q=2\pi/(3a)

. At which of the two points do phase and group velocity differ more, in relative terms, and what does that say about where on the curve the two speeds diverge most?

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