Configuration Entropy

In statistical mechanics, configuration entropy is the portion of a system's entropy that is related to the position of its constituent particles rather than to their velocity or momentum. It is physically related to the number of ways of arranging all the particles of the system while maintaining some overall set of specified system properties, such as energy. The configurational entropy is also known as microscopic entropy or conformational entropy in the study of macromolecules. In general, configurational entropy is the foundation of statistical thermodynamics.

It can be shown that the variation of configuration entropy of thermodynamic systems (e.g., ideal gas, and other systems with a vast number of internal degrees of freedom) in thermodynamic processes is equivalent to the variation of the macroscopic entropy defined as dS = δQ/T, where δQ is the heat exchanged between the system and the surrounding media, and T is temperature. Therefore configuration entropy is the same as macroscopic entropy.