Density functional theory test study on the CO ···· He dimer.

In the current paper we have investigated the bonding properties of the weakly bound van der Waals CO ···· He dimer by means of the Perdew–Wang91 exchange and Perdew–Wang correlation (PWPW) and Adamo and Barone's Becke-style one-parameter functional using the modified Perdew–Wang91 exchange and Perdew–Wang correlation (mPW1PW) exchange-correlation functionals in the framework of the supermolecule approach, using density functional theory local-spin-optimized atom-centered basis sets, complemented with bond functions optimized at the mPW1PW level of theory. These calculations show that the use of the mPW1PW functional using bond functions gives a realistic representation of the interaction-energy potential for this van der Waals molecular complex, as compared with reference Møller–Plesset perturbation theory calculations. In contrast, the PWPW functional is unable to describe the bonding properties of the system, and all values obtained with this functional approximation are considered out-of-scale compared with the rest of the calculations presented in this contribution. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 95: 177–183, 2003 [ABSTRACT FROM AUTHOR]