# Bracket size and sqrt problem

How can I make the top line of the sqrt display correctly as well the last right bracket in appropriate size?

    \documentclass[a4paper,12pt]{article}
\begin{document}
$$\label{eq:teh} T (w,V_{bias},E) \propto \exp\left[{-2w \enspace \sqrt{ \frac{2m}{\hbar^2} \left( \frac{\phi_{tip}-\phi_{sample}}{2} + \frac{eV_{bias}}{2} - E \right) }}\right]$$
\end{document}

• Are you referring to the broken horizontal rule of the \sqrt? That is most likely only an artefact of the zoom level in your viewer, as I don't see that.
– Werner
Aug 3, 2016 at 16:07
• the square root ought to join up better than that, please fix your example to be a complete small document that produces the picture (so showing font usage) note always use \mathrm or \mathit for multi-letter words so _{\mathrm{sample}} the default math italic font is designed to make adjacent not look like a word but as a product of variables. Aug 3, 2016 at 16:08

I would not make the square bracket taller than the horizontal line produced by the \sqrt directive. To create a bit of whitespace between the end of the square root's horizontal bar and the closing ], insert a \, (thinspace) instruction immediately before the closing square bracket.

\documentclass[a4paper,12pt]{article}
\usepackage{amsmath}
\begin{document}
$$\label{eq:teh} T (w,V_{\mathrm{bias}},E) \propto \exp \Biggl[ -2w \, \sqrt{ \frac{2m}{\hbar^2} \biggl( \frac{\phi_{\mathrm{tip}}-\phi_{\mathrm{sample}}}{2} + \frac{eV_{\mathrm{bias}}}{2} - E \biggr) }\, \Biggr]$$
\end{document}


After some vertical and horizontal correction (we are cheating that the square root is a bit higher):

\documentclass[a4paper,12pt]{article}
\begin{document}
$$\label{eq:teh} T (w,V_{\mathrm{bias}},E) \propto \exp\left[{-2w \enspace \sqrt{ \frac{2m}{\hbar^2} \left( \frac{\phi_{\mathrm{tip}}-\phi_{\mathrm{sample}}}{2} + \frac{eV_{\mathrm{bias}}}{2} - E \right) }}^{\rule{0mm}{2mm}}\,\right] %as much height as you need - PS$$
\end{document}


Why not a simplebmatrix environment instead of a \left[ … \right] pair? The top of the brackets is exactly at the height of the horizontal line of the square root symbol?

\documentclass[a4paper,12pt]{article}

\usepackage{mathtools}%

\begin{document}

$$\label{eq:teh} T (w,V_\text{bias},E) \propto \exp \begin{bmatrix} {-2w \enspace √{ \frac{2m}{\hbar²} \left( \frac{\phi_\text{tip}-\phi_\text{sample}}{2} + \frac{eV_\text{bias}}{2} - E \right) }\:} \end{bmatrix}$$

\end{document}


• Why a bmatrix? Aug 3, 2016 at 20:03
• A bracket matrix. Amsmath also defines the matrix, pmatrix, vmatrix and Vmatrix environments. Aug 3, 2016 at 20:08
• Yes, I meant that this is not a bracket matrix, and I don't see why use it in this case. Aug 3, 2016 at 20:21
• Simply to have brackets of a correct size. Aug 3, 2016 at 20:31
• It's not the bmatrix but the \textstyle inside whate makes it “smaller”. Aug 3, 2016 at 21:49
\documentclass[a4paper,12pt]{article}
\usepackage{amsmath}
\begin{document}
$$\label{eq:teh}\delimitershortfall=-1pt T (w,V_{\mathrm{bias}},E) \propto \exp \left[ -2w \, \sqrt{ \frac{2m}{\hbar^2} \left( \frac{\phi_{\mathrm{tip}}-\phi_{\mathrm{sample}}}{2} + \frac{eV_{\mathrm{bias}}}{2} - E \right) }\, \right]$$
\end{document}