diff --git a/Manuscript/EPAWTFT.tex b/Manuscript/EPAWTFT.tex index fafdbb2..83d98fa 100644 --- a/Manuscript/EPAWTFT.tex +++ b/Manuscript/EPAWTFT.tex @@ -1581,7 +1581,7 @@ While the diagonal quadratic approximants provide significanty improved estimate ground-state energy, we can use our knowledge of the UMP singularity structure to develop even more accurate results. We have seen in previous sections that the UMP energy surface -contains only \titou{square-root branch cuts} that approach the real axis in the limit $U/t \to \infty$. +contains only square-root branch cuts that approach the real axis in the limit $U/t \to \infty$. Since there are no true poles on this surface, we can obtain more accurate quadratic approximants by taking $d_q = 0$ and increasing $d_r$ to retain equivalent accuracy in the square-root term [see Eq.\eqref{eq:QuadApp}]. Figure~\ref{fig:nopole_quad} illustrates this improvement for the pole-free [3/0,4] quadratic @@ -1633,7 +1633,8 @@ that can be used to extract further information about the exact result. The Shanks transformation presents one approach for extracting this information and accelerating the rate of convergence of a sequence.\cite{Shanks_1955,BenderBook} -\hugh{Consider the partial sums +\titou{T2: $N$ is defined as the number of electrons. Maybe we should use $n$ instead?} +Consider the partial sums $S_N = \sum_{k=0}^{N} a_k$ defined from the truncated summation of an infinite series $ S = \sum_{k=0}^{\infty} a_k$. @@ -1642,7 +1643,7 @@ If the series converges, then the partial sums will tend to the exact result \lim_{N\rightarrow \infty} S_N = S. \end{equation} The Shanks transformation attempts to generate increasingly accurate estimates of this -limt by defining a new series as +limit by defining a new series as \begin{equation} T(S_N) = \frac{S_{N+1} S_{N-1} - S_{N}^2}{S_{N+1} + S_{N-1} - 2 S_{N}}. \end{equation} @@ -1655,7 +1656,7 @@ the approximate form \end{equation} Furthermore, while this transformation can accelerate the convergence of a series, there is no guarantee that this acceleration will be fast enough to significantly -improve the accuracy of low-order approximations.} +improve the accuracy of low-order approximations. \hugh{To the best of our knowledge, the Shanks transformation has never previously been applied to the acceleration of the MP series.