Differences

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--- events:2016_summer_school:gpw [2018/05/29 22:09] – [Multigrids] mwatkins
+++ events:2016_summer_school:gpw [2020/08/21 10:15] (current) – external edit 127.0.0.1
@@ Line 398: / Line 398: @@
 \sum_{\alpha \beta} P_{\alpha \beta} \bar{\phi}_{\alpha \beta} (\mathbf{r}) = n(\mathbf{R})
 $$
-where $n(\mathbf{R})$ is the density at grid points in the cell, and $\bar{\phi}_{\alpha \beta}$ are the products of two basis functions
+where $n(\mathbf{R})$ is the density at grid points in the cell, and $\bar{\phi}_{\alpha \beta}$ are the products of two basis functions.
-{{materials/collocate.bmp}}
   * numerical approximation of the gradient $n(\mathbf{R}) \rightarrow \nabla n(\mathbf{R})$
@@ Line 432: / Line 431: @@
 {{http://ars.els-cdn.com/content/image/1-s2.0-S0010465505000615-gr002.gif}}
-GTH pseudos have small density at the core - graph of density and $v_{XC}$ through a water molecule. These spikes can cause ripples in the energy as atoms move relative to the grid.
+GTH pseudos have small density at the core - graph of density and $v_{XC}$ through a water molecule. These spikes can cause ripples in the energy as atoms move relative to the grid. These can be very problematic when trying to calculate vibrational frequencies.
-There are smoothing routines `&XC_GRID / XC_DERIV`, but probably best to stick with the defaults ... whatever you do don't change settings between simulations you want to compare.
+There are smoothing routines `&XC_GRID / XC_DERIV`, see the exercise [[events:2018_summer_school:converging_cutoff]].
 {{http://ars.els-cdn.com/content/image/1-s2.0-S0010465505000615-gr003.gif}}
-avoid with higher cutoff, or GAPW methodology.
+Avoid ripples with higher a cutoff, or GAPW methodology.
+Whatever you do don't change settings between simulations you want to compare.
-These can be very problematic when trying to calculate vibrational frequencies.
 ==== Multigrids ====