  It is often difficult to quantitatively determine if a new molecular
simulation algorithm or software properly implements sampling of the desired
thermodynamic ensemble. We present some simple statistical analysis procedures
to allow sensitive determination of whether a de- sired thermodynamic ensemble
is properly sampled. We demonstrate the utility of these tests for model
systems and for molecular dynamics simulations in a range of situations,
includ- ing constant volume and constant pressure simulations, and describe an
implementation of the tests designed for end users.
