events:2016_summer_school:gpw
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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 | ||
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\sum_{\alpha \beta} P_{\alpha \beta} \bar{\phi}_{\alpha \beta} (\mathbf{r}) = n(\mathbf{R}) | \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/ | + | |
* numerical approximation of the gradient $n(\mathbf{R}) \rightarrow \nabla n(\mathbf{R})$ | * numerical approximation of the gradient $n(\mathbf{R}) \rightarrow \nabla n(\mathbf{R})$ | ||
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{{http:// | {{http:// | ||
- | 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 `& | + | |
+ | There are smoothing routines `& | ||
{{http:// | {{http:// | ||
- | avoid with higher cutoff, or GAPW methodology. | + | Avoid ripples |
+ | |||
+ | 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 ==== | ==== Multigrids ==== |
events/2016_summer_school/gpw.1527631743.txt.gz · Last modified: 2020/08/21 10:14 (external edit)