Types of CDW¶

If the new unit cell after CDW formation is an integer times larger than the original, then it is commensurate. Otherwise, it is incommensurate.

A CDW is commensurate if and only if the wave vector describing the CDW is a rational number times one of the vectors which make up the Reciprocal lattice of the crystal. In practice, the denominator of that rational number needs to be small, and the number needs to be independent of temperature.