diff --git a/notes/ewald.lyx b/notes/ewald.lyx index e80afa8..12b3ead 100644 --- a/notes/ewald.lyx +++ b/notes/ewald.lyx @@ -3199,6 +3199,10 @@ safe radius . \end_layout +\begin_layout Subsubsection +Short-range (real-space) sum +\end_layout + \begin_layout Standard For the short-range part \begin_inset Formula $\sigma_{n}^{m(2)}$ @@ -3255,7 +3259,87 @@ Apparently, this expression is problematic for \end_inset . - Hence it might make sense to take a rougher estimate TODO + Hence it might make sense to take a rougher estimate using (for +\begin_inset Formula $n=1$ +\end_inset + +) +\begin_inset Formula +\begin{eqnarray*} +B_{R_{\mathrm{s}}}\left[f_{\eta}^{\mathrm{L}}\right] & = & \int_{R_{\mathrm{s}}}^{\infty}r^{2}\int_{\eta}^{\infty}e^{-r^{2}\xi^{2}}e^{k^{2}/4\xi^{2}}\xi^{2}\ud\xi\,\ud r\\ + & \le & e^{k^{2}/4\eta^{2}}\int_{R_{\mathrm{s}}}^{\infty}\int_{\eta}^{\infty}e^{-r^{2}\xi^{2}}r^{2}\xi^{2}\ud\xi\,\ud r, +\end{eqnarray*} + +\end_inset + +now the integration on the last line is +\begin_inset Quotes eld +\end_inset + +symmetric +\begin_inset Quotes erd +\end_inset + + w.r.t. + +\begin_inset Formula $R_{\mathrm{s}}\leftrightarrow\eta$ +\end_inset + +, so we can write either TODO; dammit, I should implement the hypergeometric + fn instead. +\begin_inset Formula +\[ +B_{R_{\mathrm{s}}}\left[f_{\eta}^{\mathrm{L}}\right]\le e^{k^{2}/4\eta^{2}}\int_{R_{\mathrm{s}}}^{\infty}\int_{\eta}^{\infty}e^{-r^{2}\xi^{2}}r^{2}\xi^{2}\ud\xi\,\ud r +\] + +\end_inset + + +\end_layout + +\begin_layout Subsubsection +Long-range ( +\begin_inset Formula $k$ +\end_inset + +-space) sum +\end_layout + +\begin_layout Standard +For +\begin_inset Formula $\beta_{pq}>k$ +\end_inset + +, we have +\begin_inset Formula $\gamma_{pq}=\frac{\beta_{pq}}{k}\sqrt{1-\left(k/\beta_{pq}\right)^{2}}\le\frac{\beta_{pq}}{k}$ +\end_inset + +, hence +\begin_inset Formula $\Gamma_{j,pq}=\Gamma\left(\frac{1}{2}-j,\frac{\beta_{pq}^{2}-k^{2}}{4\eta^{2}}\right)$ +\end_inset + + and the +\begin_inset Formula $\beta_{pq}$ +\end_inset + +-dependent part of +\begin_inset Formula $\sigma_{n}^{m(1)}$ +\end_inset + + is +\end_layout + +\begin_layout Standard +\begin_inset Formula +\begin{eqnarray*} +\left(\beta_{pq}/k\right)^{n-2j}\Gamma_{j,pq}\left(\gamma_{pq}\right)^{2j-1} & = & \left(\beta_{pq}/k\right)^{n-2j}\Gamma\left(\frac{1}{2}-j,\frac{\beta_{pq}^{2}-k^{2}}{4\eta^{2}}\right)\left(\frac{\beta_{pq}^{2}}{k^{2}}-1\right)^{j-\frac{1}{2}}\\ + & \le & \left(\beta_{pq}/k\right)^{n-2j}\left(\frac{\beta_{pq}^{2}-k^{2}}{4\eta^{2}}\right)^{-j-\frac{1}{2}}e^{-\frac{\beta_{pq}^{2}-k^{2}}{4\eta^{2}}}\left(\frac{\beta_{pq}^{2}}{k^{2}}-1\right)^{j-\frac{1}{2}}\\ + & & TODO +\end{eqnarray*} + +\end_inset + + \end_layout \begin_layout Section