3. Dynamics

Invited Lecture

A CONTINUUM MECHANIST’S REVISIT OF MOLECULAR DYNAMICS

PAOLO PODIO-GUIDUGLI
Università Di Roma Torvergata
Rome, Italy

Abstract. When seen from the viewpoint of continuum physics, the intriguing novelty of the Andersen-Parrinello-Rahman MD method to simulate solid/solid phase transitions is that it mixes macroscopic informati on - the MD-cell deformation descriptor - with the microscopic information about the motion of the molecules within the cell, while letting the thermal fluctuati ons of both molecules and cell be driven by a macroscopic control, the applied stress. The success of the method depends crucially on a shrewd specificati on of the total kinetic energy. One purpose of my talk is to discuss a set of assumptions under which the kinetic energy takes exactly the form postulated in A-P-R MD. Another purpose is to show how one of those assumptions - namely, irrotationality of cell motion - should be incorporated in whatever metadynamics one proposes to explore the energy landscape along paths connecting local minima. A third and last purpose is to point out a connection between zero-temperature A-P-R MD and the search via the Cauchy-Born Rule for an elastic stored energy mapping consistent with a given intermolecular potential.

Acknowledgement. This lecture was made possible through fi nancial support from Pró-Reitoria de Pós-Graduação (PRPG/USP).