Analytical representation of half-width for molecular ro-vibrational lines in the case of dipole-dipole and dipole-quadrupole interactions

The analytical formula for half-width of molecular ro-vibrational lines is obtained for the case of dipole-dipole and dipole-quadrupole interactions. This formula depends on the variable parameters, which have to be determined by fitting to experimental half-widths or to half-widths calculated by semi-classical methods. The application of the analytical formula to the H2O-H2O, NH3-NH3, DCl-HCl and CO-H2O systems is discussed.