Weiss zone law
= Weiss zone law
{c}
{title2=$hu+kv+lw=0$}
A lattice direction $[uvw]$ lies parallel to a plane $(hkl)$ exactly when $hu+kv+lw=0$. Indeed, their direct and reciprocal lattice vectors have <dot product> proportional to this expression. This statement holds for noncubic cells as well; angles between directions still require the direct-lattice <metric tensor>.