Efficient Chebyshev polynomial approach to quantum conductance calculations: Application to twisted bilayer graphene

In recent years, Chebyshev polynomial expansions of tight-binding Green's functions have been successfully applied to the study a wide range spectral and transport properties materials. However, application approach quantum noninteracting mesoscopic systems with leads has hampered by lack suitable expansion Landaeur's formula or one its equivalent formulations in terms Keldysh's perturbation theory. Here, we tackle this issue means hybrid that combines efficiency convenience complex absorbing potentials calculate conductance two-terminal devices computationally expedient accurate fashion. The versatility is demonstrated for twisted bilayer graphene (TBG) up $2.3\ifmmode\times\else\texttimes\fi{}{10}^{6}$ atomic sites. Our results highlight importance moir\'e effects, interlayer scattering events, twist-angle disorder determining curves small twist angle near TBG magic ${\ensuremath{\theta}}_{m}\ensuremath{\approx}1.{1}^{\ensuremath{\circ}}$.