H\"uckel theory of large-scale planar organic structures

H\"uckel theory applies, if at all, to the $\pi$ orbitals of planar organic molecules, treating only one $p_z$-like basis function for each atomic site. The only advantage of this is that one has closed formulas for properties of rather large, complex structures. We develop $\pi$-orbital Green function calculations for $\vec{k}_{\|}$ resolved density of states of ordered layers of organic adsorbates, such as might pertain to angle-resolved photoemission. Simple-minded though it may be, the theory leads to closed formulas for a wide variety of molecular architectures.