Third law of thermodynamics
From SklogWiki
The third law of thermodynamics (or Nernst's theorem after the experimental work of Walther Nernst) states that the entropy of a system approaches a minimum (that of its ground state) as one approaches the temperature of absolute zero. One can write
where N is the number of particles. Note that there are systems whose ground state entropy is not zero, for example metastable states or glasses, or systems with weakly or non-coupled spins that are not subject to an ordering field.
[edit] Implications
The heat capacity (for either pressure or volume) tends to zero as one approaches absolute zero. From
one has
thus 
as 
, otherwise the integrand would become infinite.
Similarly for the thermal expansion coefficient
