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--- exercise:nacl_free_energy [2014/05/30 11:31] – [Average Largange multiplier for NaCl in water at 350K (incomplete)] oschuett
+++ exercise:2014_ethz_mmm:nacl_free_energy [2014/10/15 13:36] – oschuett
@@ Line 34: / Line 34: @@
 From these forces the free energy difference can be obtained via integration:
 \begin{equation}
-\Delta A = \int_a^b F(x)\, dx
+\Delta A = -\int_a^b F(x)\, dx
 \end{equation}
 A dissociation profile can be obtained by choosing the closest distance $d_{min}$ as lower integration-bound:
 \begin{equation}
-A(d) = \int_{d_{min}}^d F(x)\, dx
+A(d) = -\int_{d_{min}}^d F(x)\, dx
 \end{equation}
@@ Line 50: / Line 50: @@
 ===== 3. Task: Free energy curve of NaCl in water at 350K =====
-Take the solvated system from the [[exercise:nacl_md | first exercise]] and add the constraint for a distance of 2.9 Å. Then run 100.000 MD steps MD at 350K. From the MD output calculate the average Largange multiplier. As a check for convergence you can divide the trajectory into two parts and calculate the average for each part separately. Once you are convinced of the result you can use it to complete the table given below. From the complete table calculate the free energy dissociation profile via numerical integration.
+Take the solvated system from the [[nacl_md | first exercise]] and add the constraint for a distance of 2.9 Å. Then run 100.000 MD steps MD at 350K. From the MD output calculate the average Largange multiplier. As a check for convergence you can divide the trajectory into two parts and calculate the average for each part separately. Once you are convinced of the result you can use it to complete the table given below. From the complete table calculate the free energy dissociation profile via numerical integration.
 ===== Required Files =====