  We study molecular diffusion in linear nanopores with different types of
roughness in the so-called Knudsen regime. Knudsen diffusion represents the
limiting case of molecular diffusion in pores, where mutual encounters of the
molecules within the free pore space may be neglected and the time of flight
between subsequent collisions with the pore walls significantly exceeds the
interaction time between the pore wall and the molecules. We present an
extension of a commonly used procedure to calculate transport diffusion
coefficients. Our results show that using this extension, the coefficients of
self- and transport diffusion in the Knudsen regime are equal for all regarded
systems, which improves previous literature data.
