`flalign` 环境中的两行文本

Question

我想实现下图所示的效果。基本上，我想让这两行非常长的文本分成两行，如下所示。我的主要问题是，如果我将文本保持在一行中flalign，那么整个右侧文本将向左移动。这是我的代码。

\documentclass[a4paper]{article}
\usepackage{mathtools}
\usepackage{nccmath}
\usepackage[margin=1in]{geometry}

\newcommand \widebox[1]{\setlength\fboxsep{6pt}\boxed {\enspace#1\enspace}}
\newcommand \dpartial[2]{\frac{\partial #1}{\partial #2}}
\newcommand \ddef[2]{\frac{d #1}{d #2}}
\newcommand \spac{\\[0.6em]}

\setlength\parindent{0pt}
\numberwithin{equation}{section}

\title{\vspace{-5em} QM Formula List}
\author{David}
\date{}

\begin{document}
\maketitle
\begin{flalign*}
   &i\hbar \dpartial{\Psi}{t} = -\frac{\hbar ^2}{2m}\dpartial{^2 \Psi}{x^2}+V\Psi &&\text{Shr\"odinger Equation}\spac
   &\widehat{p} = -i \hbar \dpartial{}{x}                                         &&\text{Momentim Operator} \spac
   &\widehat{H} = -\frac{\hbar ^2}{2m} \ddef{^2 \psi}{x^2} + V                    &&\text{Energy Operator} \spac
   &-\frac{\hbar^2}{2m}\ddef{^2 \psi}{x^2} + V \psi = E \psi                      &&\text{Time-independent Schr\"odinger Equation} \spac
\end{flalign*}
\end{document}

Answer 1

将项目设置为tabular：

\documentclass[a4paper]{article}
\usepackage{mathtools}
\usepackage{nccmath}
\usepackage[margin=1in]{geometry}

\newcommand \widebox[1]{\setlength\fboxsep{6pt}\boxed {\enspace#1\enspace}}
\newcommand \dpartial[2]{\frac{\partial #1}{\partial #2}}
\newcommand \ddef[2]{\frac{d #1}{d #2}}
\newcommand \spac{\\[0.6em]}

\setlength\parindent{0pt}
\numberwithin{equation}{section}

\title{\vspace{-5em} QM Formula List}
\author{David}
\date{}

\begin{document}
\maketitle
\begin{flalign*}
   &i\hbar \dpartial{\Psi}{t} = -\frac{\hbar ^2}{2m}\dpartial{^2 \Psi}{x^2}+V\Psi &&\text{Shr\"odinger Equation}\spac
   &\widehat{p} = -i \hbar \dpartial{}{x}                                         &&\text{Momentim Operator} \spac
   &\widehat{H} = -\frac{\hbar ^2}{2m} \ddef{^2 \psi}{x^2} + V                    &&\text{Energy Operator} \spac
   &-\frac{\hbar^2}{2m}\ddef{^2 \psi}{x^2} + V \psi = E \psi                      &&\begin{tabular}{@{}l@{}}Time-independent \\ Schr\"odinger Equation\end{tabular} \spac
\end{flalign*}
\end{document}

Answer 2

使用parbox[length]{content}是另一种选择。

代码

\documentclass[a4paper]{article}
\usepackage{mathtools}
\usepackage{nccmath}
\usepackage[margin=1in]{geometry}

\newcommand \widebox[1]{\setlength\fboxsep{6pt}\boxed {\enspace#1\enspace}}
\newcommand \dpartial[2]{\frac{\partial #1}{\partial #2}}
\newcommand \ddef[2]{\frac{d #1}{d #2}}
\newcommand \spac{\\[0.6em]}

\setlength\parindent{0pt}
\numberwithin{equation}{section}

\title{\vspace{-5em} QM Formula List}
\author{David}
\date{}

\begin{document}
\maketitle
\begin{flalign*}
   &i\hbar \dpartial{\Psi}{t} = -\frac{\hbar ^2}{2m}\dpartial{^2 \Psi}{x^2}+V\Psi &&\text{Shr\"odinger Equation}\spac
   &\widehat{p} = -i \hbar \dpartial{}{x}                                         &&\text{Momentim Operator} \spac
   &\widehat{H} = -\frac{\hbar ^2}{2m} \ddef{^2 \psi}{x^2} + V                    &&\text{Energy Operator} \spac
   &-\frac{\hbar^2}{2m}\ddef{^2 \psi}{x^2} + V \psi = E \psi                      &&\parbox{4cm}{Time-independent Schr\"odinger Equation} \spac
\end{flalign*}
\end{document}

Answer 3

您的公式位于左边距。要使它们（更）居中，您应该&&在它们前面添加一对。如果您希望它们真正居中，您可以使用环境alignat*：

\documentclass[a4paper]{article}
\usepackage[utf8]{inputenc}
\usepackage{mathtools}
\usepackage{nccmath}
\usepackage[margin=1in, showframe]{geometry}
\usepackage{stackengine}
\setstackEOL{\\}

\newcommand \widebox[1]{\setlength\fboxsep{6pt}\boxed {\enspace#1\enspace}}
\newcommand \dpartial[2]{\frac{\partial #1}{\partial #2}}
\newcommand \ddef[2]{\frac{d #1}{d #2}}
\newcommand \spac{\\[0.6em]}

\setlength\parindent{0pt}
\numberwithin{equation}{section}

\title{\vspace{-5em} QM Formula List}
\author{David}
\date{}

\begin{document}
\maketitle
\begin{flalign*}
  &  &   &i\hbar \dpartial{\Psi}{t} = -\frac{\hbar ^2}{2m}\dpartial{^2 \Psi}{x^2}+V\Psi &&\text{Shrödinger Equation}\spac
  &  &   &\widehat{p} = -i \hbar \dpartial{}{x}                                         && \text{Momentum Operator}\spac
  &  &   &\widehat{H} = -\frac{\hbar ^2}{2m} \ddef{^2 \psi}{x^2} + V    &&\text{Energy Operator} \spac
   &  &  &-\frac{\hbar^2}{2m}\ddef{^2 \psi}{x^2} + V \psi = E \psi      & &\Centerstack[l]{Time-independent\\ Schrödinger Equation} \spac
\end{flalign*}
\vskip2ex
\begin{alignat*}{2}
   &i\hbar \dpartial{\Psi}{t} = -\frac{\hbar ^2}{2m}\dpartial{^2 \Psi}{x^2}+V\Psi &&\text{\rlap{\hspace{4em}Shrödinger Equation}}\spac
   &\widehat{p} = -i \hbar \dpartial{}{x}                                         & &\text{\rlap{\hspace{4em}Momentum Operator}}\spac
   &\widehat{H} = -\frac{\hbar ^2}{2m} \ddef{^2 \psi}{x^2} + V    &&\text{\rlap{\hspace{4em}Energy Operator}} \spac
   &-\frac{\hbar^2}{2m}\ddef{^2 \psi}{x^2} + V \psi = E \psi      &&\rlap{\hspace{4em}\Centerstack[l]{Time-independent\\ Schrödinger Equation}} \spac
\end{alignat*}

\end{document}