A (Semiempirical) Crystal Orbital Formalism

In the Introduction it has been mentioned that the large unit cell dimensions of organometallic polymers prevent the application of traditional solid state techniques. Published computational results in this field are thus sparse. In the following we give a description of a semiempirical crystal orbital (CO) approach which has been used by the author in a number of electronic structure investigations of organometallic 1D stacks. The basic framework of this CO scheme is of an INDO-type (intermediate neglegt of differential overlap) approximation supplemented by the simpler CNDO (complete neglect of differential overlap) technique. The semiempirical LCAO variants have been designed for atoms up to bromine under the inclusion of the first (i.e. 3d) transition-metal series [III.1,III.2].