A Priori Prediction of Heats of Vaporization and Sublimation by EFP2-MD

New theoretical procedures were proposed for the heats of vaporization (Delta H-vap) and sublimation (Delta H-sub) predictions by adopting effective fragment potential version 2-molecular dynamics (EFP2-MD) simulations. The particular EFP2, as generated by HF/6-31+ +G(2d,2p), yielded excellent results in the predictions of Delta H-vap, where mean absolute deviation (MAD) and root-mean-square deviation (RMSD) for 16 molecules were 0.34 and 0.44 kcal/mol, respectively. By introducing a uniform scaling factor, we further derived a prediction procedure for Delta H-sub, where its MAD and RMSD were 0.76 and 0.90 kcal/mol, respectively. Because EFP2-MD does not require any ab initio computations during simulation, computational overhead of our procedures is minimal. We believe that our new procedures for the Delta H-vap and Delta H-sub predictions could be widely applicable in the areas where accurate chemical information for virtual molecules is critical.