Large time-step, fast-switching free energy calculations with non-symplectic integrators
- Author(s)
- Harald Oberhofer, Christoph Dellago
- Abstract
In recent work (Lechner et al., J. Chem. Phys. 124, 044113 (2006)) we have shown how to generalize Jarzynski's fast switching method for the computation of free energy differences to large time-step trajectories. Although Such trajectories mimic the true time evolution of the system only approximately, the resulting free energies are exact. The large time-step approach, which can lead to considerable efficiency increases, is particularly simple for phase space volume conserving algorithms such as the velocity Verlet integrator. In this paper we explore the consequences of using non-symplectic integration algorithms, which do not conserve phase space volume, in fast switching simulations. We find that if the phase space volume expansion or contraction is taken into account properly, the large time-step approach remains valid and may yield considerable efficiency improvements. If, however, the change in phase space volume caused by the integration algorithm is simply neglected, serious inaccuracies of the free energy estimate may arise, particularly for large system sizes.
- Organisation(s)
- Computational Materials Physics, Computational and Soft Matter Physics
- Journal
- Israel Journal of Chemistry
- Volume
- 47
- Pages
- 215-223
- No. of pages
- 9
- ISSN
- 0021-2148
- DOI
- https://doi.org/10.1560/IJC.47.2.215
- Publication date
- 2007
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 103018 Materials physics
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/0376f3bc-0448-4f1d-b97a-e455c2d70205