I have a really long equation, which I want to split into two lines. I searched the internet and found that it works with a split environment. It actually does! But I have big (or automatically sized) brackets which start on the first and end on the second line. But the second line has no closing bracket - it gets lost somewhere. Could you help me fix it?
\usepackage{amsmath}
\usepackage{amsthm}
\usepackage{amsbsy}
\usepackage{amssymb}
\begin{document}
\begin{equation}
\label{eq:vanderWaals}
\begin{split}
V_{vdW} = &-\frac{A}{6}\left[\frac{2r_1r_2}{h^2+2(r_1+r_2)h}
+\frac{2r_1r_2}{h^2+2(r_1+r_2)h+4r_1r_2}\\
&+ln\left(\frac{h^2+2(r_1+r_2)h}{h^2+2(r_1+r_2)h+4r_1r_2}\right)\right],
\end{split}
\end{equation}
\end{document}

\leftand\rightpairs are not allowed to span line breaks in a multi-line displayed equation structure. Your best option is to replace\left[with\biggl[and to replace\right]with\biggr]. And, while you're at it, you might also replace\left(with\biggl(and replace\right)with\biggr). – Mico Jul 13 '19 at 14:01ln("natural logarithm", right?) with\ln. The backslash character makes\lna macro, which gets expanded to an upright (not math-italic) "ln". (ii) You should definitely replace= &-in the first row with&= -, to assure that the-symbol before\fracgets treated as a unary rather than as a binary operator. – Mico Jul 13 '19 at 14:12