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Using \AA for angstrom is not working for me. When I write 1 \AA all I get is 2 (r)A in the output. I have tried putting the curly brackets around it {\AA} but still no success. I do not know why. I have even tried changing the fonts I am using. Any help will be appreciated.

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4  
It may be that you include another package that overwrites the definition of \AA. What does your document preamble look like? –  Werner Jul 27 '11 at 18:10
7  
Please add a minimal working example (MWE) that illustrates your problem –  Seamus Jul 27 '11 at 18:16
1  
@Godey: did you do by any chance \def\r{(r)} or something similar? This would explain what you get. –  Bruno Le Floch Jul 28 '11 at 13:37
    
Yes I had defined these new commands and I think it was messing with something. Got it working ater commenting it out. Dunno why.%\newcommand{\bea}{\begin{eqnarray}} %\newcommand{\eea}{\end{eqnarray}} %%\newcommand{\bi}{\bibitem} %%\newcommand{\eps}{\epsilon} Thanks for the input. –  Godey Jul 29 '11 at 21:03

2 Answers 2

up vote 14 down vote accepted

\AA is a text command which essentially becomes \r{A}; \r is the command producing the "ring accent" and is invalid in math mode. Here's a way:

\newcommand{\angstrom}{\mbox{\normalfont\AA}}

If the unit must be used also in subscripts or superscripts,

\usepackage{amsmath} % or simply amstext
\newcommand{\angstrom}{\text{\normalfont\AA}}

Following daleif suggestion, a more compact version would be

\usepackage{amsmath} % or simply amstext
\newcommand{\angstrom}{\textup{\AA}}

(amsmath is necessary, otherwise \textup doesn't change sizes in subscripts).

However, the best practice when dealing with units is to use siunitx as suggested by quinmars. The macros \si and \SI made available by it provide the correct spacing.

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1  
For correct operation in all math styles the definition can also be \text{\AA}; requires amsmath. –  Andrey Vihrov Jul 28 '11 at 9:05
    
for a unit \textup{\AA} would be better as \textit{$\text{\AA}$} leave the \AA italic. But is should be treated as a unit and thus siunitx is a better solution. –  daleif Jul 28 '11 at 11:11
    
@daleif That's why I put \normalfont. –  egreg Jul 28 '11 at 11:32
    
Got it working. Thanks for all the input –  Godey Jul 29 '11 at 21:00

I'd suggest to use the siunitx package. If you want a quantity, use:

The lattice constant $a = \SI{2.0}{\angstrom}$ is ...

if you only need the unit, use:

Atomic distances are measured in \si{\angstrom}.
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2  
And you can get the real ångström character with the lmodern package and \sisetup{text-angstrom={Å},math-angstrom={\text{Å}}} with UTF-8 input. –  Andrey Vihrov Jul 28 '11 at 9:11

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