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Unformatted text preview: 10.675 LECTURE 20 RICK RAJTER 1. Today ⇒ Exploring Complex Free Energy Landscapes Course Notes ⇒ ⇒ Simple vs Complex Free Energy Landscapeds ⇒ PS Time Scales, and what they can do. ⇒ Thermodynamic Integration ⇒ Blue Moon Ensemble (Constrained Dynamics) ⇒ Transition Path Sampling ⇒ Examples 2. Simple System K AB , A → B Date : Fall 2004. 1 2 RICK RAJTER K AB = K b T h e − Gτ K b T ps (picosecond) time scales in CPMD What size Δ G can be overcome in 1 ps at room T? K b T = 0 . 6 Kcal/mole K b T 10 12 s − 1 = 6 x 10 12 s − 1 e − Δ G ‡ Δ G ‡ 1 . 1 kcal/mole Can we used information on ps time scales to somehow compute Δ G ‡ 3. Sampling For E KS , σ large. Large eV’s for ps energies but, for quantities related to free energy, sigma’s are an order of magnitude lower. Discretize the curve and small 1.1 kcal/mole variation in each space/region 4. Thermodynamic Integration H 1 → H 2 Free energy state function can integrate on non-physical pathway....
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This note was uploaded on 11/27/2011 for the course CHEMICAL E 20.410j taught by Professor Rogerd.kamm during the Spring '03 term at MIT.
- Spring '03