We report a new approach to calculate intermolecular potentials for polyatomic molecules in the gas phase. The proposed hybrid model employs a combination of molecular dynamics and Monte Carlo methods. The calculations are performed for the hafnium tetrakis-dipivaloylmethanate molecule with known positional parameters of all its 129 atoms. The Buckingham potential is used to calculate atom-atom coupling. The proposed modified Lennard-Jones potential can be used to describe interactions between hafnium tetrakis-dipivaloylmethanate molecules (Hf(thd)4) in the gas phase. The developed method for the calculation of the intermolecular potential in the gas phase can be applied to virtually any molecules with known positional parameters of atoms in their composition.