▎ 摘　　要

A recently derived formula for complex conductivity of monolayer graphene is analyzed. We show that the real and imaginary parts in this formula obey the Kramers-Kronig dispersion relations, which are a good test for validity of the formula for complex conductivity of monolayer graphene. We consider also an additional test for this formula, sensitive to the integral characteristic of the conductance such as the famous f-sum rule. We write it in the two dimensional form and show that it fulfils identically if we admit the cyclotron mass as an effective one and take the principal value of the integral. We find a deep relation between the graphene complex optical conductivity singularities and electrons Zitterbewegung (ZB) in graphene with frequency omega(ZB). Namely, the value of ZB frequency is related with the recently found magnitudes of the inductance L and capacitance C by Thomson's formula, that is, omega(ZB) = 1/root LC.