ABSTRACT
Condensed matter refers to materials that are neither gaseous nor liquid, where the atoms arrange themselves in some kind of structure. The atoms come together due to their attractive interactions, and can form ordered arrays (crystals) and apparently disordered or less-ordered patterns (soft-matter, fractal aggregates, etc.). The periodicity of ordered arrays not only makes their analysis simpler, but leads to the possibility of well-defined and long-lived lattice vibrations or phonons that would not be present in soft-matter materials.
