Effective Atom-Atom Potentials for H2O-He and H2O-Ar Systems

An atom-atom interaction potential for the H₂O–A system is proposed in a form that depends on the normal coordinates q of an H₂O molecule. Vibrational and rotational corrections to the effective potential for H₂O–He and H₂O–Ar systems are calculated and their impact on the calculated broadening coefficients у is analysed for the absorption lines of different vibrational H₂O bands in the case of broadening by helium and argon. It is shown that excitation of the stretching modes of vibrations in the H₂O molecule leads to an increase in the calculated broadening coefficients y. Accounting for rotational corrections, у increases by 15% for the lines with rotational quantum number K_a = 9 for the lower transition state in the case of broadening by He and by 4% when broadening by Ar