sum of states, \(P(\varepsilon)\)

https://doi.org/10.1351/goldbook.S06134
The total number of states for a system corresponding to an energy \(\varepsilon\) less than or equal to a specified value.
Source:
PAC, 1996, 68, 149. (A glossary of terms used in chemical kinetics, including reaction dynamics (IUPAC Recommendations 1996)) on page 188 [Terms] [Paper]