Linewidths of C[sub 2]H[sub 2] perturbed by H[sub 2]: calculations from an ab initio potential and comparison with experimental results

In this work we present a theoretical and experimental study of the acetylene‐hydrogen system. An ab initio potential surface has been obtained by ab initio quantum chemistry methods. This 4‐dimensional potential is further used to compute pressure broadening coefficients of C2H2 isotropic Raman Q lines on a large scale of temperatures within both the close‐clouping approach and the coupled‐states approximation. Experimental data for the acetylene V2 Raman lines broadened by molecular hydrogen are obtained using stimulated Raman spectroscopy. Comparisons of theoretical values with experimental data measured at 143 K are promising. In addition, we discerned means of improving computational efficiency.