WIP tweaking infinite lattice text
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@ -172,6 +172,24 @@
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number = {4}
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}
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@article{gavin_feast_2018,
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title = {{{FEAST}} Eigensolver for Nonlinear Eigenvalue Problems},
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author = {Gavin, Brendan and Mi{\k{e}}dlar, Agnieszka and Polizzi, Eric},
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year = {2018},
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month = jul,
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volume = {27},
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pages = {107--117},
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issn = {1877-7503},
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doi = {10.1016/j.jocs.2018.05.006},
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url = {http://www.sciencedirect.com/science/article/pii/S1877750318302096},
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urldate = {2020-06-03},
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abstract = {The linear FEAST algorithm is a method for solving linear eigenvalue problems. It uses complex contour integration to calculate the eigenvectors associated with eigenvalues that are located inside some user-defined region in the complex plane. This makes it possible to parallelize the process of solving eigenvalue problems by simply dividing the complex plane into a collection of disjoint regions and calculating the eigenpairs in each region independently of the eigenpairs in the other regions. In this paper we present a generalization of the linear FEAST algorithm that can be used to solve nonlinear eigenvalue problems. Like its linear progenitor, the nonlinear FEAST algorithm can be used to solve nonlinear eigenvalue problems for the eigenpairs corresponding to eigenvalues that lie in a user-defined region in the complex plane, thereby allowing for the calculation of large numbers of eigenpairs in parallel. We describe the nonlinear FEAST algorithm, and use several physically motivated examples to demonstrate its properties.},
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file = {/u/46/necadam1/unix/.mozilla/firefox/6m8fw48s.default/zotero/storage/DCVYC9IH/Gavin ym. - 2018 - FEAST eigensolver for nonlinear eigenvalue problem.pdf;/u/46/necadam1/unix/.mozilla/firefox/6m8fw48s.default/zotero/storage/LJHSWVFQ/S1877750318302096.html},
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journal = {Journal of Computational Science},
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keywords = {Contour integration,FEAST,Nonlinear eigenvalue problem,Polynomial eigenvalue problem,Quadratic eigenvalue problem,Residual inverse iteration},
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language = {en}
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}
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@article{guo_lasing_2019,
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title = {Lasing at \${{K}}\$ {{Points}} of a {{Honeycomb Plasmonic Lattice}}},
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author = {Guo, R. and Ne{\v c}ada, M. and Hakala, T. K. and V{\"a}kev{\"a}inen, A. I. and T{\"o}rm{\"a}, P.},
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@ -451,7 +451,12 @@ noprefix "false"
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\end_inset
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.
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The gain in the system introduces some challenges, which we will discuss
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\begin_inset Note Note
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status open
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\begin_layout Plain Layout
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The gain in the system introduces some challenges, which we will discuss
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in Section
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\begin_inset CommandInset ref
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LatexCommand eqref
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@ -465,6 +470,11 @@ noprefix "false"
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.
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\end_layout
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\end_inset
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\end_layout
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\begin_layout Subsection
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Numerical solution
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\end_layout
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@ -628,16 +638,17 @@ noprefix "false"
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\end_layout
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\begin_layout Standard
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An alternative, more robust approach to generic minimisation algorithms
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is Beyn's contour integral method
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An alternative, faster and more robust approach to generic minimisation
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algorithms are eigensolvers for nonlinear eigenvalue problems based on
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contour integration
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\begin_inset CommandInset citation
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LatexCommand cite
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key "beyn_integral_2012"
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key "beyn_integral_2012,gavin_feast_2018"
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literal "false"
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\end_inset
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which finds the roots of
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which are able to find the roots of
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\begin_inset Formula $M\left(\omega,\vect k\right)=0$
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\end_inset
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@ -753,7 +764,7 @@ empty
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as defined in
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\begin_inset CommandInset ref
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LatexCommand eqref
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reference "eq:lilgamma"
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reference "eq:lilgamma_old"
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plural "false"
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caps "false"
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noprefix "false"
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@ -1091,7 +1102,24 @@ noprefix "false"
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\end_layout
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\begin_layout Standard
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For reader's reference, we list the Ewald-type formulae for lattice sums
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The lattice sums
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\begin_inset Formula $\sigma_{l,m}\left(\vect k,\vect s\right)$
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\end_inset
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are related to what is also called
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\emph on
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structural constants
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\emph default
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in some literature
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\begin_inset CommandInset citation
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LatexCommand cite
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key "kambe_theory_1967,kambe_theory_1967-1,kambe_theory_1968"
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literal "false"
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\end_inset
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, but the phase and normalisation differ.
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For reader's reference, we list the Ewald-type formulae for lattice sums
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\begin_inset Formula $\sigma_{l,m}\left(\vect k,\vect s\right)$
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\end_inset
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@ -1129,7 +1157,7 @@ FP: Check sign of s
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\begin_inset Formula
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\begin{multline}
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\sigma_{l,m}^{\left(\mathrm{S},\eta\right)}\left(\vect k,\vect s\right)=-\frac{2^{l+1}i}{\kappa^{l+1}\sqrt{\pi}}\sum_{\vect n\in\ints^{d}}\left(1-\delta_{\vect{R_{n}},-\vect s}\right)\left|\vect{R_{n}+\vect s}\right|^{l}\ush lm\left(\vect{R_{n}+\vect s}\right)e^{i\vect k\cdot\left(\vect{R_{n}+\vect s}\right)}\\
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\times\int_{\eta}^{\infty}e^{-\left|\vect{R_{n}+\vect s}\right|^{2}\xi^{2}}e^{-\kappa/4\xi^{2}}\xi^{2l}\ud\xi\\
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\times\int_{\eta}^{\infty}e^{-\left|\vect{R_{n}+\vect s}\right|^{2}\xi^{2}}e^{-\kappa^{2}/4\xi^{2}}\xi^{2l}\ud\xi\\
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+\delta_{\vect{R_{n}},-\vect s}\frac{\delta_{l0}\delta_{m0}}{\sqrt{4\pi}}\Gamma\left(-\frac{1}{2},-\frac{\kappa^{2}}{4\eta^{2}}\right)\ush lm\left(\vect{R_{n}+\vect s}\right).\label{eq:Ewald in 3D short-range part}
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\end{multline}
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@ -1209,6 +1237,32 @@ Poznámka ohledně zahození radiální části u kulových fcí?
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\end_layout
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\begin_layout Standard
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In practice, the integrals in
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\begin_inset CommandInset ref
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LatexCommand eqref
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reference "eq:Ewald in 3D short-range part"
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plural "false"
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caps "false"
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noprefix "false"
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\end_inset
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can be easily evaluated by numerical quadrature and the incomplete
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\begin_inset Formula $\Gamma$
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\end_inset
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-functions using the series or continued fraction representations from
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\begin_inset CommandInset citation
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LatexCommand cite
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key "NIST:DLMF"
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literal "false"
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\end_inset
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.
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\end_layout
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\begin_layout Standard
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The explicit form of the long-range part of the lattice sum depends on the
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lattice dimensionality.
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@ -1221,7 +1275,11 @@ The explicit form of the long-range part of the lattice sum depends on the
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\begin_inset Formula $\left\{ \vect b_{i}\right\} _{i=1}^{d}$
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\end_inset
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lying in the same subspace as the direct lattice vectors
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lying in the same
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\begin_inset Formula $d$
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\end_inset
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-dimensional subspace as the direct lattice vectors
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\begin_inset Formula $\left\{ \vect a_{i}\right\} _{i=1}^{d}$
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\end_inset
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@ -1233,12 +1291,15 @@ The explicit form of the long-range part of the lattice sum depends on the
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\end_layout
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\begin_layout Standard
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If
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\begin_layout Paragraph
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Case
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\begin_inset Formula $d=3$
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\end_inset
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,
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\end_layout
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\begin_layout Standard
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\begin_inset Formula
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\begin{equation}
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\sigma_{l,m}^{\left(\mathrm{L},\eta\right)}\left(\vect k,\vect s\right)=\frac{4\pi i^{l+1}}{\kappa\mathcal{A}}\sum_{\vect K\in\Lambda^{*}}\underbrace{e^{i\vect K\cdot\vect s}}_{\text{nemá tu být \ensuremath{\vect{k\cdot s}?}}}\frac{\left(\left|\vect k+\vect K\right|/\kappa\right)^{l}}{\kappa^{2}-\left|\vect k+\vect K\right|^{2}}e^{\left(\kappa^{2}-\left|\vect k+\vect K\right|^{2}\right)/4\eta^{2}}\ush lm\left(\vect k+\vect K\right)\label{eq:Ewald in 3D long-range part 3D}
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@ -1255,12 +1316,16 @@ regardless of chosen coordinate axes.
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cases).
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\end_layout
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\begin_layout Standard
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If
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\begin_layout Paragraph
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Case
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\begin_inset Formula $d=2$
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\end_inset
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, reasonable explicit forms assume that the lattice lies inside the
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\end_layout
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\begin_layout Standard
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Reasonable explicit forms assume that the lattice lies inside the
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\begin_inset Formula $xy$
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\end_inset
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@ -1325,7 +1390,7 @@ FP: check sign of
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\begin_inset Formula
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\begin{multline}
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\sigma_{l,m}^{\left(\mathrm{L},\eta\right)}\left(\vect k,\vect s\right)=-\frac{i^{l+1}}{\kappa^{2}\mathcal{A}}\pi^{3/2}2\left(\left(l-m\right)/2\right)!\left(\left(l+m\right)/2\right)!\times\\
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\times\sum_{\vect K\in\Lambda^{*}}\underbrace{e^{i\vect K\cdot\vect s}}_{\text{nemá tu být \ensuremath{\vect{k\cdot s}?}}}\ush lm\left(\vect k+\vect K\right)\sum_{j=0}^{l-\left|m\right|}\left(-1\right)^{j}\left(\gamma\left(\left|\vect k+\vect K\right|/\kappa\right)\right)^{2j+1}\Delta_{j}\left(\frac{\kappa^{2}\gamma\left(\left|\vect k+\vect K\right|/\kappa\right)}{4\eta^{2}},-i\kappa\gamma\left(\left|\vect k+\vect K\right|/\kappa\right)s_{\perp}\right)\times\\
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\times\sum_{\vect K\in\Lambda^{*}}\underbrace{e^{i\vect K\cdot\vect s}}_{\text{nemá tu být \ensuremath{\vect{k\cdot s}?}}}\ush lm\left(\vect k+\vect K\right)\sum_{j=0}^{l-\left|m\right|}\left(-1\right)^{j}\left(\gamma\left(\left|\vect k+\vect K\right|/\kappa\right)\right)^{2j+1}\Delta_{j}\left(\frac{\kappa^{2}\gamma\left(\left|\vect k+\vect K\right|/\kappa\right)^{2}}{4\eta^{2}},-i\kappa\gamma\left(\left|\vect k+\vect K\right|/\kappa\right)s_{\perp}\right)\times\\
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\times\sum_{\begin{array}{c}
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s\\
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j\le s\le\min\left(2j,l-\left|m\right|\right)\\
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@ -1343,7 +1408,7 @@ status open
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\begin_inset Formula
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\begin{multline}
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\sigma_{l,m}^{\left(\mathrm{L},\eta\right)}\left(\vect k,\vect s\right)=-\frac{i^{l+1}}{\kappa^{d}\mathcal{A}}\pi^{2+\left(3-d\right)/2}2\left(\left(l-m\right)/2\right)!\left(\left(l+m\right)/2\right)!\times\\
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\times\sum_{\vect K\in\Lambda^{*}}\underbrace{e^{i\vect K\cdot\vect s}}_{\text{nemá tu být \ensuremath{\vect{k\cdot s}?}}}\ush lm\left(\vect k+\vect K\right)\sum_{j=0}^{\left[\left(l-\left|m\right|/2\right)\right]}\frac{\left(-1\right)^{j}\left(\left|\vect k+\vect K\right|/\kappa\right)^{l-2j}\Gamma\left(\frac{d-1}{2}-j,\frac{\kappa^{2}\gamma\left(\left|\vect k+\vect K\right|/\kappa\right)}{4\eta^{2}}\right)}{j!\left(\frac{1}{2}\left(l-m\right)-j\right)!\left(\frac{1}{2}\left(l+m\right)-j\right)!}\times\\
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\times\sum_{\vect K\in\Lambda^{*}}\underbrace{e^{i\vect K\cdot\vect s}}_{\text{nemá tu být \ensuremath{\vect{k\cdot s}?}}}\ush lm\left(\vect k+\vect K\right)\sum_{j=0}^{\left[\left(l-\left|m\right|/2\right)\right]}\frac{\left(-1\right)^{j}\left(\left|\vect k+\vect K\right|/\kappa\right)^{l-2j}\Gamma\left(\frac{d-1}{2}-j,\frac{\kappa^{2}\gamma\left(\left|\vect k+\vect K\right|/\kappa\right)^{2}}{4\eta^{2}}\right)}{j!\left(\frac{1}{2}\left(l-m\right)-j\right)!\left(\frac{1}{2}\left(l+m\right)-j\right)!}\times\\
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\times\left(\gamma\left(\left|\vect k+\vect K\right|/\kappa\right)\right)^{2j+3-d}\label{eq:Ewald in 3D long-range part 1D 2D-1}
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\end{multline}
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@ -1355,18 +1420,155 @@ status open
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\end_inset
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where
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\begin_inset Formula $\gamma\left(z\right)=\left(z^{2}-1\right)^{\frac{1}{2}}$
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\begin_inset Formula
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\begin{equation}
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\gamma\left(z\right)=\left(z^{2}-1\right)^{\frac{1}{2}},\label{eq:lilgamma}
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\end{equation}
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\end_inset
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and
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\begin_inset Formula
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\begin{equation}
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\Delta_{j}\left(x,z\right)=\int_{x}^{\infty}t^{\frac{-1}{2}-n}\exp\left(-t+\frac{z^{2}}{4t}\right)\ud t.\label{eq:Delta_j}
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\end{equation}
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\end_inset
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If the normal component
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\begin_inset Formula $s_{\bot}$
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\end_inset
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is zero, in the last sum in eq.
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\begin_inset CommandInset ref
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LatexCommand eqref
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reference "eq:Ewald in 3D long-range part 1D 2D"
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plural "false"
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caps "false"
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noprefix "false"
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\end_inset
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only one term (
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\begin_inset Formula $s=2j$
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\end_inset
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) will remain if
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\begin_inset Formula $l-\left|m\right|$
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\end_inset
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is even; for
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\begin_inset Formula $l-\left|m\right|$
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\end_inset
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odd, the sum will vanish completely.
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Moreover,
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\begin_inset Formula $\Delta_{j}\left(x,0\right)=\Gamma\left(1/2-j,x\right)$
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\end_inset
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.
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If
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\begin_inset Formula $s_{\bot}\ne0$
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\end_inset
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, the integral
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\begin_inset Formula $\Delta_{j}\left(x,z\right)$
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\end_inset
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can be evaluated e.g.
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using the Taylor series
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\lang finnish
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\begin_inset Formula
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\[
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\Delta_{j}\left(x,z\right)=\int_{x}^{\infty}t^{\frac{-1}{2}-n}\exp\left(-t+\frac{z^{2}}{4t}\right)\ud t
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\Delta_{j}\left(x,z\right)=\sum_{k=0}^{\infty}\Gamma\left(\frac{1}{2}-j-k,x\right)\frac{\left(z/2\right)^{2k}}{k!}
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\]
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\end_inset
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and if the normal component
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which is the first choice for small
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\begin_inset Formula $z$
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\end_inset
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\lang english
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.
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Kambe
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\begin_inset CommandInset citation
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LatexCommand cite
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key "kambe_theory_1968"
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literal "false"
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\end_inset
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mentions a recurrence formula that can be obtained integrating
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\begin_inset CommandInset ref
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LatexCommand eqref
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reference "eq:Delta_j"
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plural "false"
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caps "false"
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noprefix "false"
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\end_inset
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by parts (note that the signs are wrong in
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\begin_inset CommandInset citation
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LatexCommand cite
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key "kambe_theory_1968"
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literal "false"
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\end_inset
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)
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\begin_inset Formula
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\begin{equation}
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\Delta_{j+1}\left(x,z\right)=\frac{4}{z^{2}}\left(\left(\frac{1}{2}-j\right)\Delta_{j}\left(x,z\right)-\Delta_{j-1}\left(x,z\right)+x^{\frac{1}{2}-j}e^{-x+\frac{z^{2}}{4x}}\right)\label{eq:Delta_j recurrent}
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\end{equation}
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\end_inset
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with the first two terms
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\begin_inset Formula
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\begin{align*}
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\Delta_{0}\left(x,z\right) & =\frac{\sqrt{\pi}}{2}e^{-x^{2}+\frac{z^{2}}{4x}}\left(w\left(-\frac{z}{2\sqrt{x}}+i\sqrt{x}\right)+w\left(\frac{z}{2\sqrt{x}}+i\sqrt{x}\right)\right),\\
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\Delta_{1}\left(x,z\right) & =i\frac{\sqrt{\pi}}{z}e^{-x^{2}+\frac{z^{2}}{4x}}\left(w\left(-\frac{z}{2\sqrt{x}}+i\sqrt{x}\right)-w\left(\frac{z}{2\sqrt{x}}+i\sqrt{x}\right)\right),
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\end{align*}
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\end_inset
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where
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\begin_inset Formula $w\left(z\right)=e^{-z^{2}}\left(1+2i\pi^{-1/2}\int_{0}^{z}e^{t^{2}}\ud t\right)$
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\end_inset
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is the Faddeeva function.
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However, the recurrence formula
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\begin_inset CommandInset ref
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LatexCommand eqref
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reference "eq:Delta_j recurrent"
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plural "false"
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caps "false"
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noprefix "false"
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\end_inset
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is unsuitable for numerical evaluation if
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\begin_inset Formula $z$
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\end_inset
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is small or
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\begin_inset Formula $j$
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\end_inset
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is large due to its numerical instability.
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\end_layout
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\begin_layout Standard
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\begin_inset Note Note
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status open
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\begin_layout Plain Layout
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and if the normal component
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\begin_inset Formula $s_{\perp}$
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\end_inset
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|
@ -1380,7 +1582,17 @@ where
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\end_inset
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The function
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\end_layout
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\end_inset
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\begin_inset Note Note
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status open
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\begin_layout Plain Layout
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The function
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\begin_inset Formula $\gamma\left(z\right)$
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\end_inset
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@ -1397,71 +1609,11 @@ noprefix "false"
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is defined as
|
||||
\begin_inset Formula
|
||||
\begin{equation}
|
||||
\gamma\left(z\right)=\left(z-1\right)^{\frac{1}{2}}\left(z+1\right)^{\frac{1}{2}},\quad-\frac{3\pi}{2}<\arg\left(z-1\right)<\frac{\pi}{2},-\frac{\pi}{2}<\arg\left(z+1\right)<\frac{3\pi}{2}.\label{eq:lilgamma}
|
||||
\gamma\left(z\right)=\left(z-1\right)^{\frac{1}{2}}\left(z+1\right)^{\frac{1}{2}},\quad-\frac{3\pi}{2}<\arg\left(z-1\right)<\frac{\pi}{2},-\frac{\pi}{2}<\arg\left(z+1\right)<\frac{3\pi}{2}.\label{eq:lilgamma_old}
|
||||
\end{equation}
|
||||
|
||||
\end_inset
|
||||
|
||||
The Ewald parameter
|
||||
\begin_inset Formula $\eta$
|
||||
\end_inset
|
||||
|
||||
determines the pace of convergence of both parts.
|
||||
The larger
|
||||
\begin_inset Formula $\eta$
|
||||
\end_inset
|
||||
|
||||
is, the faster
|
||||
\begin_inset Formula $\sigma_{l,m}^{\left(\mathrm{S},\eta\right)}\left(\vect k,\vect s\right)$
|
||||
\end_inset
|
||||
|
||||
converges but the slower
|
||||
\begin_inset Formula $\sigma_{l,m}^{\left(L,\eta\right)}\left(\vect k,\vect s\right)$
|
||||
\end_inset
|
||||
|
||||
converges.
|
||||
Therefore (based on the lattice geometry) it has to be adjusted in a way
|
||||
that a reasonable amount of terms needs to be evaluated numerically from
|
||||
both
|
||||
\begin_inset Formula $\sigma_{l,m}^{\left(\mathrm{S},\eta\right)}\left(\vect k,\vect s\right)$
|
||||
\end_inset
|
||||
|
||||
and
|
||||
\begin_inset Formula $\sigma_{l,m}^{\left(\mathrm{L},\eta\right)}\left(\vect k,\vect s\right)$
|
||||
\end_inset
|
||||
|
||||
.
|
||||
For one-dimensional, square, and cubic lattices, the optimal choice is
|
||||
|
||||
\begin_inset Formula $\eta=\sqrt{\pi}/p$
|
||||
\end_inset
|
||||
|
||||
where
|
||||
\begin_inset Formula $p$
|
||||
\end_inset
|
||||
|
||||
is the direct lattice period
|
||||
\begin_inset CommandInset citation
|
||||
LatexCommand cite
|
||||
key "linton_lattice_2010"
|
||||
literal "false"
|
||||
|
||||
\end_inset
|
||||
|
||||
.
|
||||
\begin_inset Note Note
|
||||
status open
|
||||
|
||||
\begin_layout Plain Layout
|
||||
\begin_inset Marginal
|
||||
status open
|
||||
|
||||
\begin_layout Plain Layout
|
||||
Whatabout different geometries?
|
||||
\end_layout
|
||||
|
||||
\end_inset
|
||||
|
||||
|
||||
\end_layout
|
||||
|
||||
|
@ -1491,7 +1643,12 @@ FP: I have some error estimates derived in my notes.
|
|||
\end_layout
|
||||
|
||||
\begin_layout Standard
|
||||
For a two-dimensional lattice, the incomplete
|
||||
One pecularity of the two-dimensional case is the two-branchedness of the
|
||||
function
|
||||
\begin_inset Formula $\gamma\left(z\right)$
|
||||
\end_inset
|
||||
|
||||
and the incomplete
|
||||
\begin_inset Formula $\Gamma$
|
||||
\end_inset
|
||||
|
||||
|
@ -1499,12 +1656,26 @@ For a two-dimensional lattice, the incomplete
|
|||
\begin_inset Formula $\Gamma\left(\frac{1}{2}-j,z\right)$
|
||||
\end_inset
|
||||
|
||||
in the long-range part has a branch point at
|
||||
\begin_inset Formula $z=0$
|
||||
appearing in the long-range part.
|
||||
As a consequence, if we now explicitly label the dependence on the wavenumber,
|
||||
|
||||
\begin_inset Formula $\sigma_{l,m}^{\left(\mathrm{L},\eta\right)}\left(\kappa,\vect k,\vect s\right)$
|
||||
\end_inset
|
||||
|
||||
and special care has to be taken when choosing the appropriate branch.
|
||||
If the wavenumber of the medium has a positive imaginary part,
|
||||
has branch points at
|
||||
\begin_inset Formula $\kappa=\left|\vect k+\vect K\right|$
|
||||
\end_inset
|
||||
|
||||
for every reciprocal lattice vector
|
||||
\begin_inset Formula $\vect K$
|
||||
\end_inset
|
||||
|
||||
.
|
||||
If the wavenumber
|
||||
\begin_inset Formula $\kappa$
|
||||
\end_inset
|
||||
|
||||
of the medium has a positive imaginary part,
|
||||
\begin_inset Formula $\Im\kappa>0$
|
||||
\end_inset
|
||||
|
||||
|
@ -1527,17 +1698,19 @@ noprefix "false"
|
|||
\end_inset
|
||||
|
||||
converges absolutely even in the direct space, and it is equal to the Ewald
|
||||
sum with the principal value of the incomplete
|
||||
\begin_inset Formula $\Gamma$
|
||||
sum with the principal branches used both in
|
||||
\begin_inset Formula $\gamma\left(z\right)$
|
||||
\end_inset
|
||||
|
||||
function being used in
|
||||
\begin_inset CommandInset ref
|
||||
LatexCommand eqref
|
||||
reference "eq:Ewald in 3D long-range part 1D 2D z = 0"
|
||||
plural "false"
|
||||
caps "false"
|
||||
noprefix "false"
|
||||
and
|
||||
\begin_inset Formula $\Gamma\left(\frac{1}{2}-j,z\right)$
|
||||
\end_inset
|
||||
|
||||
|
||||
\begin_inset CommandInset citation
|
||||
LatexCommand cite
|
||||
key "linton_lattice_2010"
|
||||
literal "false"
|
||||
|
||||
\end_inset
|
||||
|
||||
|
@ -1546,7 +1719,7 @@ noprefix "false"
|
|||
\begin_inset Formula $\kappa$
|
||||
\end_inset
|
||||
|
||||
, the branch choice is made in such way that
|
||||
, we typically choose the branch in such way that
|
||||
\begin_inset Formula $W_{\alpha\beta}\left(\vect k\right)$
|
||||
\end_inset
|
||||
|
||||
|
@ -1650,34 +1823,102 @@ status open
|
|||
\end_inset
|
||||
|
||||
|
||||
\end_layout
|
||||
|
||||
\begin_layout Paragraph
|
||||
Case
|
||||
\begin_inset Formula $d=1$
|
||||
\end_inset
|
||||
|
||||
|
||||
\end_layout
|
||||
|
||||
\begin_layout Standard
|
||||
In practice, the integrals in
|
||||
\begin_inset CommandInset ref
|
||||
LatexCommand eqref
|
||||
reference "eq:Ewald in 3D short-range part"
|
||||
plural "false"
|
||||
caps "false"
|
||||
noprefix "false"
|
||||
|
||||
For one-dimensional chains, the easiest choice is to align the lattice with
|
||||
the
|
||||
\begin_inset Formula $z$
|
||||
\end_inset
|
||||
|
||||
can be easily evaluated by numerical quadrature and the incomplete
|
||||
\begin_inset Formula $\Gamma$
|
||||
axis.
|
||||
\end_layout
|
||||
|
||||
\begin_layout Subsubsection
|
||||
Choice of Ewald parameter and high-frequency breakdown
|
||||
\end_layout
|
||||
|
||||
\begin_layout Standard
|
||||
The Ewald parameter
|
||||
\begin_inset Formula $\eta$
|
||||
\end_inset
|
||||
|
||||
-functions using the series 8.7.3 from
|
||||
determines the pace of convergence of both parts.
|
||||
The larger
|
||||
\begin_inset Formula $\eta$
|
||||
\end_inset
|
||||
|
||||
is, the faster
|
||||
\begin_inset Formula $\sigma_{l,m}^{\left(\mathrm{S},\eta\right)}\left(\vect k,\vect s\right)$
|
||||
\end_inset
|
||||
|
||||
converges but the slower
|
||||
\begin_inset Formula $\sigma_{l,m}^{\left(L,\eta\right)}\left(\vect k,\vect s\right)$
|
||||
\end_inset
|
||||
|
||||
converges.
|
||||
Therefore (based on the lattice geometry) it has to be adjusted in a way
|
||||
that a reasonable amount of terms needs to be evaluated numerically from
|
||||
both
|
||||
\begin_inset Formula $\sigma_{l,m}^{\left(\mathrm{S},\eta\right)}\left(\vect k,\vect s\right)$
|
||||
\end_inset
|
||||
|
||||
and
|
||||
\begin_inset Formula $\sigma_{l,m}^{\left(\mathrm{L},\eta\right)}\left(\vect k,\vect s\right)$
|
||||
\end_inset
|
||||
|
||||
.
|
||||
For one-dimensional, square, and cubic lattices, the optimal choice for
|
||||
small frequencies (wavenumbers) is
|
||||
\begin_inset Formula $\eta=\sqrt{\pi}/p$
|
||||
\end_inset
|
||||
|
||||
where
|
||||
\begin_inset Formula $p$
|
||||
\end_inset
|
||||
|
||||
is the direct lattice period
|
||||
\begin_inset CommandInset citation
|
||||
LatexCommand cite
|
||||
key "NIST:DLMF"
|
||||
key "linton_lattice_2010"
|
||||
literal "false"
|
||||
|
||||
\end_inset
|
||||
|
||||
.
|
||||
\begin_inset Note Note
|
||||
status open
|
||||
|
||||
\begin_layout Plain Layout
|
||||
\begin_inset Marginal
|
||||
status open
|
||||
|
||||
\begin_layout Plain Layout
|
||||
Whatabout different geometries?
|
||||
\end_layout
|
||||
|
||||
\end_inset
|
||||
|
||||
|
||||
\end_layout
|
||||
|
||||
\end_inset
|
||||
|
||||
|
||||
\end_layout
|
||||
|
||||
\begin_layout Standard
|
||||
\begin_inset Note Note
|
||||
status open
|
||||
|
||||
\begin_layout Subsection
|
||||
Physical interpretation of wavenumber with negative imaginary part; screening
|
||||
\begin_inset CommandInset label
|
||||
|
@ -1687,6 +1928,15 @@ name "subsec:Physical-interpretation-of"
|
|||
\end_inset
|
||||
|
||||
|
||||
\end_layout
|
||||
|
||||
\begin_layout Plain Layout
|
||||
left out for the time being
|
||||
\end_layout
|
||||
|
||||
\end_inset
|
||||
|
||||
|
||||
\end_layout
|
||||
|
||||
\begin_layout Subsection
|
||||
|
@ -1749,7 +1999,7 @@ noprefix "false"
|
|||
|
||||
\begin_layout Standard
|
||||
Ewald summation can be used for evaluating scattered field intensities outside
|
||||
scatterers' circumscribing spheres: thes requires expressing VSWF cartesian
|
||||
scatterers' circumscribing spheres: this requires expressing VSWF cartesian
|
||||
components in terms of scalar spherical wavefunctions defined in
|
||||
\begin_inset CommandInset ref
|
||||
LatexCommand eqref
|
||||
|
|
Loading…
Reference in New Issue