Theoretical characterization of charge-transfer reactions between N2 and O2 molecules and paramagnetic oxygen vacancies on the MgO surface

Ethanol adsorption on MgO surface with and without defects from a theoretical point of view

“…They mimic the finite size effects of the Mg +2 cation, avoiding the artificial polarization of the O À2 anions induced by the PCs [27,28], and will be designed as MG. This approach has been used in the past to study the ground state properties of MgO and has been compared to periodic approaches and more elaborate embedding schemes based on Green functions [29]. In the present work four different adsorption sites of MgO surface were considered, each of them allowing the adsorption of an ethanol molecule on a highly symmetrical MgAO pair: on the (1 0 0) plane, on an edge whose bisecting plane is oriented along the [1 1 0] direction, on an O-apical corner whose bisecting axis is oriented along the [1 1 1] direction and on a similar corner but with a Mg-apical ion.…”

Optical properties of Cu nanoclusters supported on MgO(100)

“…When one oxygen atom is removed by the surface to form an F center one has to adopt a sufficiently flexible basis set to describe the electron localization in the vacancy: the solution adopted here is to use the diffuse 6-31ϩG basis set on the Mg ions surrounding the vacancy. 33 The binding energies E ads of Cu clusters to MgO have not been corrected for the basis set superposition error ͑BSSE͒ 34 since this is not the main purpose of this paper. Furthermore, the definition of the BSSE reference energies for adsorbed metal clusters that change their structure upon adsorption is not trivial.…”

Comparison between cluster and supercell approaches: the case of defects in diamond

“…Since hydrogen is slightly less electronegative than carbon (2.20 and 2.55, respectively, according to Pauling), [61] it leaves a fraction of an electron to the C atom to which is linked, and a sort of charge wave propagates inwards. cannot be easily recovered by increasing the cluster size [37,38]. A clear example of this behavior is the HOMO-LUMO gap (E g ) that is reported in Figure 2 as a function of the C/H ratio, R, (the corresponding periodic value is also reported for comparison).…”

“…Furthermore, the cost of such calculations increases quickly, so in most of the cases the largest clusters considered contain rather a small number of atoms (say less than 100-200). [6,7] Comparisons with periodic or embedded clusters performed in the past [6,37,38] can be considered only qualitative, since differences in functionals, basis set, computational parameters and adopted computer code can introduce severe differences in the results. The cluster approach is particularly favorable for a study of defects in semiconductors, since long range electrostatic and relaxation effects are expected to be negligible.…”