Differences

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--- events:2016_summer_school:gpw [2018/06/16 21:35] – [Energy ripples] mwatkins
+++ events:2016_summer_school:gpw [2018/06/16 21:39] – [Real space integration] mwatkins
@@ 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`, see the exercise [[events:2018_summer_school:converging_cutoff]].
-Whatever you do don't change settings between simulations you want to compare.
 {{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 ====