Density of states

Number of available physical states per energy unit

In condensed matter physics, the density of states (DOS) of a system describes the number of allowed modes or states per unit energy range. The density of states is defined as D ( E) = N ( E) / V {\displaystyle D(E)=N(E)/V} , where N ( E) δ E {\displaystyle N(E)\delta E} is the number of states in the system of volume V {\displaystyle V} whose energies lie in the range from E {\displaystyle E} to E + δ E {\displaystyle E+\delta E} . It is mathematically represented as a distribution by a probability density function, and it is generally an average over the space and time domains of the various states occupied by the system.

From Wikipedia, under CC BY-SA. More on occurri.