I was just wondering, given that you have the dispersion relation omega = omega(k) for a Lenard-Jones potential in say a monatomic crystalline solid of lattice spacing a, which is proportional to sin(ka/2) where k is the wavenumber. The group velocity is the derivative of the dispersion relation with respect to k.(adsbygoogle = window.adsbygoogle || []).push({});

My Question is: Can the wavenumber take negative values in general? (Would it be physically meaningful?). I am thinking it would be okay, as the group velocity would have the same values as if k>0.

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# Lenard Jones Potential & wavenumber

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