{{indexmenu_n>2}} ====== Tesseral Harmonics (Z) ====== ~~NOTOC~~ ;;# {{ :physics_chemistry:orbitals:basisz.nb|Download a notebook that generates this page}} ;;# ### The complex spherical Harmonics are, as their name suggests complex functions. For many cases one does not need to work with complex numbers and by making a suitable linear combination of the complex orbitals one can get a real basis. The tesseral harmonics are linear combinations of the spherical harmonics with $+m$ and $-m$ such that the result is a pure real function. For $m>0$ the tesseral harmonics have a $\cos(m\phi)$ dependence, for $m<0$ they have a $\sin(m\phi)$ dependence. The tesseral harmonics are defined as: $$ Z_l^{(m)}=\left\{\begin{array}{ll} Y_l^{(0)} & m=0\\ \frac{1}{\sqrt{2}} ( Y_l^{(-m)} + (-1)^m Y_l^{( m)} ) & m>0\\ \frac{\mathrm{i}}{\sqrt{2}} ( Y_l^{( m)} - (-1)^m Y_l^{(-m)} ) & m<0 \end{array}\right. $$ These are the combined eigenstates of the operator $L^2$, $L_z^2$ and the vertical mirror plane $xz$ and $yz$. The tesseral harmonics are also known as the real spherical harmonics. The name \emph{tesseral} derives from \emph{tessera}, the small square tile of a mosaic. The real harmonics $P_l^m(\cos\theta)\cos(m\phi)$ and $P_l^m(\cos\theta)\sin(m\phi)$ have nodes on two families of curves: the $l-m$ circles of latitude where $P_l^m$ vanishes, and the $2m$ meridians where $\cos(m\phi)$ or $\sin(m\phi)$ vanishes. On the sphere, parallels and meridians cross at right angles, so for $0.#1|msort}}