On the calculation of entropy from covariance matrices of the atomic fluctuations

An ad hoc method for calculating the entropy of a biomolecular system from the covariance matrix of the atomic fluctuations is analyzed. It is shown that its essential assumption can be eliminated by a quasiharmonic analysis. The computer time required for use of the latter is of the same order as that of the former. (C) 2001 American Institute of Physics.