new fig for Pade

This commit is contained in:
Pierre-Francois Loos 2020-11-25 11:02:48 +01:00
parent 2e64d3fd35
commit a5c2a2fc7b
2 changed files with 9 additions and 0 deletions

View File

@ -1185,6 +1185,15 @@ A $[d_A/d_B]$ Pad\'e approximant is defined as
(with $b_0 = 1$), where the coefficients of the polynomials $A(\lambda)$ and $B(\lambda)$ are determined by collecting terms according to power of $\lambda$. (with $b_0 = 1$), where the coefficients of the polynomials $A(\lambda)$ and $B(\lambda)$ are determined by collecting terms according to power of $\lambda$.
Pad\'e approximants are extremely useful in many areas of physics and chemistry \cite{Loos_2013,Gluzman_2020} as they can model poles, which appears at the roots of the polynomial $B(\lambda)$. Pad\'e approximants are extremely useful in many areas of physics and chemistry \cite{Loos_2013,Gluzman_2020} as they can model poles, which appears at the roots of the polynomial $B(\lambda)$.
However, they are unable to model functions with square-root branch points, which are ubiquitous in the singularity structure of a typical perturbative treatment. However, they are unable to model functions with square-root branch points, which are ubiquitous in the singularity structure of a typical perturbative treatment.
Figure \ref{fig:PadeRMP} illustrates the improvement brought by Pad\'e approximants as compared to the usual Taylor expansion in the case of the RMP series of the Hubbard dimer for $U/t = 4.5$.
%%%%%%%%%%%%%%%%%
\begin{figure}
\includegraphics[width=\linewidth]{PadeRMP}
\caption{\label{fig:PadeRMP}
RMP ground-state energy as a function of $\lambda$ obtained with various approximations for $U/t = 4.5$.}
\end{figure}
%%%%%%%%%%%%%%%%%
%==========================================% %==========================================%
\subsection{Quadratic approximant} \subsection{Quadratic approximant}

BIN
Manuscript/PadeRMP.pdf Normal file

Binary file not shown.