How can I write my equation this way and size:
I could not find something like this arrows that can be written above and under I've tried \underrightarrow but it's not what I need. also having issues to write the whole equation in the shown way.
Solving equation with under and above right arrow
equationsmath-operators
Related Solutions
Adapting my answer at LaTeX package to help diagram translation of one language to another, I provide a first cut.
The syntax is
\notate[B<race>]{<referenced math>}{<dropline length in \baselineskips>}{<math notation>}
The <math notation> can be given as a \parbox, if longer text is needed (shown in first example below).
The MWE:
\documentclass{article}
\usepackage[usestackEOL]{stackengine}
\usepackage{scalerel}
\usepackage{graphicx,amsmath}
\parskip \baselineskip
\def\myupbracefill#1{\rotatebox{90}{\stretchto{\{}{#1}}}
\def\rlwd{.5pt}
\newcommand\notate[4][B]{%
\if B#1\else\def\myupbracefill##1{}\fi%
\def\useanchorwidth{T}%
\setbox0=\hbox{$\displaystyle#2$}%
\def\stackalignment{c}\stackunder[-6pt]{%
\def\stackalignment{c}\stackunder[-1.5pt]{%
\stackunder[2pt]{\strut $\displaystyle#2$}{\myupbracefill{\wd0}}}{%
\rule{\rlwd}{#3\baselineskip}}}{%
\strut\kern9pt$\rightarrow$\smash{\rlap{$~\displaystyle#4$}}}%
}
\begin{document}
\begin{equation*}
\implies \frac{d}{dt} \displaystyle\int_{-\infty}^{+\infty} |\psi (x, t)|^2 \, dx
= \frac{i\hbar}{2m} \left[ \psi^* \frac{\partial}{\partial x} \psi - \left( \frac{\partial}{\partial x} \psi^* \right) \psi \right] \bigg|_{-\infty}^{+\infty}
\notate[X]{{}={}}{2}{\parbox[t]{1in}{Here, $\psi$ and $\psi^*$ are the
blah-blah variables.}} 0
\hspace{5ex}
\end{equation*}
\bigskip
\[
y = \psi^*
\notate{\frac{d\psi}{dt}}{4}{
\frac{d\psi}{dt} = \frac{ih}{2m}\frac{\partial^2}{\partial t^2}\psi
- \frac{i}{h} V\psi
}
+ \notate{\frac{d\psi^*}{dt}}{1}{
\frac{d\psi*}{dt} = -\frac{ih}{2m}\frac{\partial^2}{\partial t^2}\psi^*
+ \frac{i}{h} V\psi
}
\psi
\hspace{14ex}
\]
\end{document}
Note that this solution avoids the overlapping lines shown by the OP for a multi-part comment.
Since the math notation is \rlapped, the overall effect can be shifted left as needed by adding an \hspace{<length>} to the end of the equation.
Because the math notation is \smashed, some extra skip may be needed for multi-line notations.
You can adjust the spacing above and below your equations by setting the lengths
\setlength\abovedisplayskip{20pt}
\setlength\belowdisplayskip{20pt}
\setlength\abovedisplayshortskip{20pt}
\setlength\belowdisplayshortskip{20pt}
according to your needs. If you want to do this globally, have a look at How to globally change the spacing around equations?
\documentclass[10pt]{beamer}
\setbeamersize{text margin left=0.5em, text margin right=1em}
\usefonttheme[onlymath]{serif}
\makeatletter
\renewcommand\tagform@[1]{}
\makeatother
\begin{document}
\begin{frame}
\begin{itemize}
\setlength\abovedisplayskip{20pt}
\setlength\belowdisplayskip{20pt}
\setlength\abovedisplayshortskip{20pt}
\setlength\belowdisplayshortskip{20pt}
\item iterative minimization iterative minimization iterative minimization
\begin{equation}
Hv-\lambda Nv = 0
\end{equation}
\item generalized eigenvalue problem
\begin{equation}
Hv-\lambda Nv = 0
\end{equation}
\begin{itemize}
\setlength\abovedisplayskip{20pt}
\setlength\belowdisplayskip{20pt}
\setlength\abovedisplayshortskip{20pt}
\setlength\belowdisplayshortskip{20pt}
\item effective Hamiltonian matrix $H(\mathbf{x}_S)$
\begin{equation}
Hv-\lambda Nv = 0
\end{equation}
\item normalization matrix $N(\mathbf{x}_S)$
\end{itemize}
\end{itemize}
\end{frame}
\end{document}
Best Answer
I'm not good at aligning something, but a bit hardcoding and looks close to Your example:
Here's what about the arrows:(will edit in a minute)