Molecular dynamics at constant Cauchy stress
Abstract
The Parrinello-Rahman algorithm for imposing a general state of stress in periodic molecular dynamics simulations is widely used in the literature and has been implemented in many readily available molecular dynamics codes. However, what is often overlooked is that this algorithm controls the second Piola-Kirchhoff stress as opposed to the true (Cauchy) stress. This can lead to misinterpretation of simulation results because (1) the true stress that is imposed during the simulation depends on the deformation of the periodic cell, (2) the true stress is potentially very different from the imposed second Piola-Kirchhoff stress, and (3) the true stress can vary significantly during the simulation even if the imposed second Piola-Kirchhoff is constant. We propose a simple modification to the algorithm that allows the true Cauchy stress to be controlled directly. We then demonstrate the efficacy of the new algorithm with the example of martensitic phase transformations under applied stress.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- May 11, 2016
- Source ID
- 10.1063/1.4948711
Entities
People
- Ellad B. Tadmor
- Fabio Pavia
- Joshua S. Gibson
- Noam Bernstein
- Ronald E. Miller
Organizations
- Carleton University
- National Science Foundation Directorate for Engineering
- Natural Sciences and Engineering Research Council
- Office of Naval Research Global
- Swiss Federal Institute of Technology in Lausanne
- United States Naval Research Laboratory
- University of Minnesota