New force fields for carbon dioxide and nitrogen are introduced that quantitatively reproduce the vapor–liquid equilibria (VLE) of the neat systems and their mixtures with alkanes. In addition to the usual VLE calculations for pure CO₂ and N₂, calculations of the binary mixtures with propane were used in the force‐field development to achieve a good balance between dispersive and electrostatic (quadrupole–quadrupole) interactions. The transferability of the force fields was then assessed from calculations of the VLE for the binary mixtures with n‐hexane, the binary mixture of CO₂/N₂, and the ternary mixture of CO₂ /N₂/propane. The VLE calculations were carried out using configurational‐bias Monte Carlo simulations in either the grand canonical ensemble with histogram–reweighting or in the Gibbs ensemble.