Langevin Thermostat for Rigid Body Dynamics
This provides a practical tool for molecular dynamics simulations requiring temperature control of rigid bodies, but the improvement is incremental over existing methods.
The authors developed a Langevin thermostat for rigid body dynamics using quaternions, enabling correct NVT sampling for rigid molecules. Their method, tested on the TIP4P water model, achieves accurate thermodynamic sampling with second-order integrators.
We present a new method for isothermal rigid body simulations using the quaternion representation and Langevin dynamics. It can be combined with the traditional Langevin or gradient (Brownian) dynamics for the translational degrees of freedom to correctly sample the NVT distribution in a simulation of rigid molecules. We propose simple, quasi-symplectic second-order numerical integrators and test their performance on the TIP4P model of water. We also investigate the optimal choice of thermostat parameters.