DENSITY-FUNCTIONAL THEORY APPLIED TO PROTON-TRANSFER SYSTEMS - A NUMERICAL TEST

The structure, interaction energy and proton-transfer features of the (H5O2)+ complex are determined by using a nonlocal density functional theory method developed recently by Salahub and co-workers. The results are compared to those of a high-order Moller-Plesset electron-correlation calculation. The DFT calculation predicts correctly a symmetrical configuration of the complex at the equilibrium O-O distance, and yields a correct value of the H-bonding interaction energy. For a larger O-O separation, the electronic correlation effects on the double-well proton potential curve are overestimated in the DFT approach, whereas they are well reproduced by the second-order Moller-Plesset expansion.