Quantum close-coupling (CC) and semiclassical (SC) calculations of broadening and shifting coefficients of Q(j) rovibrational lines have been performed using an nb initio potential energy surface. The agreement between the theoretical results and experimental data available up to 1000 K is very good for the broadening coefficient gamma and reasonable for the shift delta. The main interest is to test the validity of the semiclassical method versus CC calculation on a wide range of temperature to allow confident application of the SC method to more complex systems. The agreement is very satisfactory. Further the SC model permits a detailed analysis of the mechanisms involved in the temperature dependence of the molecular parameters gamma and delta. (C) 1997 American Institute of Physics.