Comment on ‘‘Extensions of the molecular dynamics simulation method. II. Isothermal systems’’

Haile and Gupta have given derivations of isothermal equations of motion for a system of N particles. The first derivation, based on generalized potentials, gives equations of motion which are derivable from a Hamiltonian and hence have four rather than three constants of the motion. These equations of motion have no obvious relevance to equilibrium statistical mechanics. Derivations which lead to isothermal equations of motion which have direct utility to statistical mechanics have been given by Evans, Hoover, and Nosé.