THERMOSTATTED MOLECULAR-DYNAMICS - HOW TO AVOID THE TODA DEMON HIDDENIN NOSE-HOOVER DYNAMICS

The Nose-Hoover thermostat, which is often used in the hope of modifyi ng molecular dynamics trajectories in order to achieve canonical-ensem ble averages, has hidden in it a Toda ''demon,'' which can give rise t o unwanted, noncanonical undulations in the instantaneous kinetic temp erature. We show how these long-lived oscillations arise from insuffic ient coupling of the thermostat to the atoms, and give straightforward , practical procedures for avoiding this weak-coupling pathology in is othermal molecular dynamics simulations.