Application of the DV-Xα cluster method to calculations of the electronic structure of silicate and phosphate glasses

摘要: The electronic structure of simple silicate and phosphate clusters, which are assumed to exist in rapidly quenched Li2OSiO2 Li2OP2O5 glasses, has been calculated by the discrete variational (DV)-Xα molecular orbital method. calculations have carried out for several sizes namely, tetrahedral units (SiO44− PO43−), dimers (Si2O76− P2O74−), trimers (Si3O96− P3O93−). For both systems valence state is characterized an occupied band, with O 2p components, unoccupied band Si or P orbitals, separated energy gap. gap between highest (HOMO) loest (LUMO) decreases increasing cluster size. A mulliken population analysis show that negative effective charge on non-bridging oxygens decreased decreasing bond order SiO PO bonds, thus strength these increased