\begin{equation*}\label{v1}
{\bf{B}}=\left[ \begin{array}{cc|cc}
\dfrac{\sqrt{2}}{2}&0&0&0\\
\dfrac{\sqrt{2}}{8}&\dfrac{\sqrt{3}\sqrt{2}}{24}&0&0\\\hline\rule{0pt}{2.7ex}
0&0&\dfrac{\sqrt{2}}{2}&0\\
0&0&\dfrac{3\sqrt{2}}{8}&\dfrac{\sqrt{3}\sqrt{2}}{24}
\end{array}\right]