Binding energies of nitrile-containing proton-bound clusters: the performance of HF, MP2 and B3-LYP vs. G2

This study assesses a variety of computational methods for calculating the binding energies of proton-bound clusters containing a nitrile. The binding energies of (HCN)2H+, (HCN)(NH3)H+, (HCN)(H2O)H+ and (HCN)(HF)H+ were calculated at the HF, MP2 and B3-LYP levels of theory with a variety of basis sets, and the results compared to previous work employing G2 based methods. Reliable binding energies could be obtained using the MP2/6-31+G(d) and B3-LYP/6-31+G(d) levels of theory. The results were extended to a total of thirteen proton-bound dimers for which G2 values are available, and four multiply hydrated clusters (HCN)(H2O)2H+, (HCN)(H2O)3H+, (CH3CN)(H2O)2H+ and (CH3CN)(H2O)3H+.