Yes i am. I think i got the answer. I believe the appropriate rule is:
\nabla \cdot \vec{μ} f = \nabla f \cdot \vec{μ} + f \nabla \cdot \vec{μ}
You need to start with
\nabla \cdot f\nabla f = \nabla f \cdot \nabla f + f(\nabla \cdot \nabla f)
which becomes:
\nabla...
Apparently,
f \nabla^2 f = \nabla \cdot f \nabla f - \nabla f \cdot \nabla f
where f is a scalar function.
Can someone please show me why this is step by step.
Feel free to use suffix notation.
Thanks in advance.