Analysis of self-consistent extended Hückel theory (SC-EHT): a new look at the old method

摘要: We present an extensive analysis of the self-consistent extended Huckel theory (SC-EHT) and discuss possibilities constructing accurate efficient semiempirical methods on its basis. describe mapping approach to derive a self-consistency correction effective 1-electron Hamiltonian (Fock) operator that is utilized in electronic structure calculations variationally minimizes total energy SC-EHT method. show can play role by definition, which case no needed. Then, method be derived from Hartree–Fock approximation Fock matrix. Therefore, based have rigorous foundations may develop family successively model Hamiltonians. analyze underlying it light existing formulations EHT indicate two major deficiencies method—neglect exchange integrals incorrect asymptotic behavior Coulomb integrals. The compared charge equilibration scheme DFTB approximations. improved version connected both them, indicating relation approximations fundamental DFT origins their potential for computations large-scale systems.