Double Hybrid Density-Functional Theory Using the Coulomb-Attenuating Method

A double hybrid approximation using the Coulomb attenting method ICAM DH is derived with range separated density functional perturatin theory in the spint of recent work by Comation et al (Phys . Rev A 2013. 88, 0225416), The Energy experssion reconvered through second order is linear in the parameters alpha- and that contraol the columba attenation. The method has been tested within the local denstiy approvimation on a small test set consising of rare-gas and alkalin-earth-meta dimers as well as claiatmics with signale, double and triple bonds. In this context the semiprical alpha = 0.19 and beta = 0.46 paramters, which were optimized for the hybrid CAM-B3LYP functional do not provide accurate interaction and total energines. Using semilocal functaions with density scalling wihc was reglected in the work, may lead to different conclusions. Calibration studies on a larger test set would be necessary at this poin. This is left for future work. Finally we propsoe as a perspetive as altennative CAM-DH approach that relies on the pertunbation expansion of a partially long-range interacting wavefuntion. In this case, the energy is not linear anymore in alpha and beta. Work is in progress in this direction, (C) 2014 Wiley Periodicals, Inc.