As pointed out by Kugel and Khomskii in their seminal work , in presence of strong electron correlation
orbitals are subject to exchange interaction and a preexisting OO tends to amplify any lattice instability.
For recovering of the electron correlation
effects--at least in pairs--and the Ti 3d orbitals additional repulsion, we use the Hubbard U parameter  as suggested by Morgade and Cabeza for Ti[O.sub.2] .
The high computational cost of SAPT calculations is associated, to a great extent, with the inclusion of intramolecular electron correlation
Dropping the reader off next to the deep end, the first chapter introduces the quantum-mechanical concepts necessary for the deep understanding of the subject: approximations to solutions of the wave function, electron correlation
and density functional theory.
Among various metal oxide NPs, CuO has attracted particular attention because it is the simplest member of the family of copper compounds and shows a range of useful physical properties such as high temperature superconductivity, electron correlation
effects, and spin dynamics [1, 2].
As widely documented in the literature, accurate estimates of electronic (hyper)polarizabilities need polarized and diffuse basis sets as well as introduction of electron correlation
These limitations include the effect of electron correlation
 and basis set deficiencies as well as inter- and intramolecular interactions.
The effects due to electron correlation
are smaller for the electron concentrations n [less than or equal to] [10.sup.21] [cm.sup.-3] used here .
Alparone, "Electron correlation
effects and density analysis of the first-order hyperpolarizability of neutral guanine tautomers," Journal of Molecular Modeling, vol.
Reprinted from publication between the middle of the 20th century and the early 21st, 113 technical papers look at quantum electron crystals, nuclear structure factor and pair potentials in some sp liquid metals, electron correlation
functions in liquid metals, Thomas-Fermi semiclassical approximations, transcending Thomas-Fermi theory, and local and non-local applications of one-body potential theory.
Strong electron correlation
and the source of enhanced thermopower
studies by means of local-scaling transformation and electron-pair density functions.