DFT performance in the IQA energy partition of small water clusters

This paper addresses an assessment of the performance of a large set of exchange-correlation functionals in the description of hydrogen bonding within the interacting quantum atoms (IQA) energy partition. Specifically, we performed IQA analyses over a series of small water clusters (H2O)n with n≤ 6. Apart from LDA-like approximations, all the considered families of exchange-correlation functionals (GGA, meta-GGA, and hybrid) reproduce the trends associated with hydrogen bond non-additive effects computed with reference Møller–Plesset and coupled cluster wave functions. In other words, the IQA energy partition together with most of the functionals addressed herein produce good results concerning the study of non-additivity in hydrogen bonds at a reduced cost as compared with correlated wave functions approximations. These conditions might be further exploited in the examination of larger hydrogen-bonded complexes.