When entropy = 0, does atomic motion stop?
Date: Before 1993
It is know that entropy is zero when a pure crystalline substance
is at absolute zero. Theoretically, does this mean that atomic motion
(electrons, etc.) stops also?
Zero entropy means that the system is in a single quantum
mechanical state, in particular, the lowest, the ground state. This means
that the particles of the system have adjusted their motions to lower their
energy as much as possible. However, because of quantum mechanical effects
there is still residual motion of the particles. This is measurable and
detectable and is often called zero point motion. It is particularly
observable in the motion of the atoms when they are studied by x-rays. Even
in the lowest energy state of a metal, the electrons are still moving around
keeping the energy as low as possible.
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Update: June 2012