Interatomic electron transport by semiempirical and ab initio tight-binding approaches -: art. no. 125101

A unified approach to interatomic electron transport within Kubo linear-response theory is sketched that is applicable both in semiempirical (matrix-element-based) and ab initio (wave-function-based) tight-binding (TB) techniques. This approach is based on a systematic neglect of the electron motion inside the atomic (Wigner-Seitz) cells leading thus to velocity operators describing pure intersite hopping. This is achieved by using piecewise constant coordinates, i.e., coordinates that are constant inside the cells. The formalism is presented within the simple semiempirical TB method, the TB linear muffin-tin orbital (LMTO) method, and the screened Korringa-Kohn-Rostoker (KKR) method with emphasis on the formal analogy of the derived formulas. The results provide a justification of current assumptions used in semiempirical TB schemes, an assessment of properties of recent TB-LMTO approaches, and an alternative formulation of electron transport within the screened KKR method. The formalism is illustrated by a calculation of residual resistivity of substitutionally disordered fcc Ag-Pd alloys.