Electronic properties of polymeric silicon hydrides

Different types of polymeric silicon hydrides are investigated using a first-principles, density-functional method. First, the trans form of polysilene, (SiH)ₓ, is considered. For the undimerized polymer a full geometry optimization is carried through, and, afterwards, starting with the optimized, undimerized structure, the process of dimerizing the polymer is studied. Here, two different ways of dimerizing are considered in order to examine the dependence of the results on the dimerization route. Secondly, the reaction between polysilene and hydrogen atoms leading to polysilane, (SiH₂{)}ₓ$, is investigated in order to demonstrate the lack of stability of polysilene. Finally, for polysilane with a planar silicon backbone the electronic properties are analyzed when varying the bond lengths and bond angles of the backbone. The results are used in providing parameters for a model Hamiltonian with which polaronic excitations are studied.