Abstract
A mathematical theorem is established for traces of products of bounded Hermitian and definite operators, a and b: for a non-negative integer. This theorem is applied to the equilibrium partition function by exploiting an infinite-product representation of the exponential function of the sum of two operators. As a result, a set of inequalities is established which yields a set of upper bounds for the partition function. This result is invariant to the particle statistics of the system. A general argument yields the result that the classical Helmholtz free-energy function serves as a lower bound to the corresponding quantum result.
- Received 1 October 1964
DOI:https://doi.org/10.1103/PhysRev.137.B1127
©1965 American Physical Society