DC Transport Coefficient Calculation by a Derivatives of Time Correlation Functions I. General Formula Derivation

Abstract

By two partial integrations in succession, Kubo’s formula for electric conductivity σ(ω), has been reduced to an expression giving σ(ω) by a force-force time correlation functions, which in the limit ω→0 behaves like an indeterminate ratio (0/0). This ratio has been resolved by the use of L’Hospital rule, and has given an expression for DC conductivity, which is suitable for practical calculation, more than original Kubo’s formula.