We have used GCMC simulation to study the adsorption of nitrogen into silt-shaped micropores at 303 K. Nitrogen was modeled as a one-center or as a two-center molecule, with or without quadrupoles. The pores were modeled as parallel smooth graphite surfaces. Pore widths, corresponding to two samples of activated carbon fiber having internal pore widths of 0.75 and 1.45 nm, were selected. The carbon to carbon distance H, needed in the potential energy calculation, was found from geometrical parameters. Two alternative methods of calculation of this quantity are discussed. Better agreement with experiment is obtained if H is based on the minimum of the interaction potential rather than the thickness of graphite plane. Differences between the one-center and two-center models were found in the smaller pore and can be attributed to the different packing available to the two models.