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Unformatted text preview: University of Virginia, MSE 4270/6270: Introduction to Atomistic Simulations, Leonid Zhigilei The extended system method for constant pressure V. Summary Equations of motion: i i i 3 / 1 i i d V m V 3 2 F V d m & & & & = ext int P P V M = & & Two systems of variables are used: 1. Real variables should be used to calculate forces, energy, structural parameters of the system. 2. Scaled variables to simulate evolution of the system (perform MD simulation). The equation of motion for the volume is defined so that deviation of the internal pressure from its average works as a negative feedback and keeps the pressure around a constant. The simulation is performed in a constant-enthalpy constant-pressure ensemble. University of Virginia, MSE 4270/6270: Introduction to Atomistic Simulations, Leonid Zhigilei Relation between the equations of motion expressed in real coordinates r i (Andersen paper in J. Chem. Phys. 72, 2384, 1980) and scaled coordinates d i (this handout): i 1/3...
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This note was uploaded on 02/14/2012 for the course MSE 4270 taught by Professor Zhigilei during the Fall '11 term at UVA.
- Fall '11