Math & Science ⇒ Grouping terms in an equation

[MasterAir]

Hi,
Is there a way of grouping terms in an equation using a curly bracket underneath the terms. Googling and searching the forums has yielded no results, I guess because I don't know the correct name for what I'm doing here.

The specific example (Hamiltonian partitioning) is as follows,

H_total = H_MM + H_LL + H_RR + H_ML + H_MR
...............|-----------------------|....|---------------|
...........................H_0....................V
H_total = H_0 + V

With the dots as whitespace and |-----| replaced by a curly bracket.

Thanks in advance for your help.

[localghost]

You are looking for the \underbrace command. See code below.

Code: Select all

\documentclass[11pt,a4paper]{article}
\usepackage{amsmath}

\begin{document}
  \begin{align*}
    \mathcal{H}_\text{total} &= \underbrace{\mathcal{H}_\text{MM} + \mathcal{H}_\text{LL} + \mathcal{H}_\text{RR}}_{\mathcal{H}_0} + \underbrace{\mathcal{H}_\text{ML} + \mathcal{H}_\text{MR}}_{V} \\
    \mathcal{H}_\text{total} &= \mathcal{H}_0 + V
  \end{align*}
\end{document}

Best regards and welcome to the board
Thorsten