RELATIVISTICALLY PARAMETERIZED EXTENDED HUCKEL THEORY

A relativistically parameterized extended Hückel molecular orbital method is outlined. One-electron effective hamiltonian matrix elements are related to the corresponding overlap matrix elements calculated in an atomic ilsjm) basis. Different atomic radial functions ar eused for the j = l + 1 2 and j = l 1 2 basis functions for a given n and l. Relativistic and non-relativistic atomic orbital energies are taken from atomic Dirac-Fock and Hartree-Fock calculations. Results are presented for the molecules I2, Br2, IBr, HI, CH4, SiH4, GeH4, SnH4, PbH4, PbH4, (114)H4 and Bi4. It is concluded that our method and its parameterization provide a semi-quantitative description of relativistic effects in chemical bonding. © 1979.