A modified thermodynamic perturbation theory of Wertheim for heteronuclear molecules

The Wertheim thermodynamic perturbation theory (TPT1) is modified for fluids of heteronuclear molecules. The equation proposed by Mansoori-Carnahan-Starling and Leland has been applied for monomers instead of the Carnahan-Starling equation. The modified TPT is compared with simulation results and other theoretical results for heteronuclear dimer, trimer, and higher mers covering a wide range of size ratios. The modified TPT gives a useful method of extending the original TPT1 model to molecules of heteronuclear hard sphere cores without introducing any parameter such as shape factor α.