# equation in math mode

$$E-\epsilon_{i}-T_{i}-V_{0,i}(\textbf{R}) \tilde \chi_{i}^(+)(\textbf{K_{i}},\textbf{R})&=0$$


Missing \$ inserted and I don't know why. Can anybody help me? thanks

-
Don't leave blank lines in math mode; LaTeX tries to interpret them as paragraph breaks, which aren't allowed in math mode. – ChrisS Apr 2 '14 at 10:17

There are some issues in your equation:

1. The & character inside equation is not allowed (it is used for alignment in other math environments).
2. You can not leave blank lines inside an equation.
3. When you say \textbf{K_{i}} you are entering text mode and the _ character is not allowed.
4. Also I think that in \textbf{K_{i}} you don't want the subscript to be bold.
5. If you want (+) to be a superscript you have to encase it in braces.

So, if you want bold letters in upright mode, substitute \textbf with \mathbf

\documentclass{article}

\begin{document}

$$E-\epsilon_{i}-T_{i}-V_{0,i}(\mathbf{R}) \tilde \chi_{i}^{(+)}(\mathbf{K}_{i},\mathbf{R})=0$$

\end{document}


-
\mathbf{K}_{i} is the correct syntax. – egreg Apr 2 '14 at 10:26
@egreg Thanks. I, too, think that the OP wanted to write that. – karlkoeller Apr 2 '14 at 10:29