In the impact approximation, the transformation of the band shape with pressure is determined by the relaxation Γ-matrix structure. According to the quasiclassical theory the Γ-structure is determined only by the parameter G, which depends on the interaction potential and reduced mass of the colliding particles. This paper presents the calculations of G and S values for CO₂ and CO molecules colliding with noble gas atoms. Experimentally measured absorption coefficients in the near band wings can be used for determining the parameters of the proposed model.