En las fronteras de la Materia Condensada

Studies of TDS, IR and NMR show the presence of four different species adsorbed on MgO: two are physisorbed, and two are species of the dissociated molecule. Methanol presents an important dipole moment of comparable size to the interatomic spacing of MgO, and the sizes of the different clusters used in the ab-initio calculations are of a few interatomic distances. One may expect a noticeable effect in the configuration end of the molecule caused by a large electronic density in edges and vertices of the cluster. These effects are naturally extended to the study of superficial defects, whereas they introduce ambiguity when considering the configuration of methanol on one clean surface of defects. The solution would be to use greater clusters, but these would require prohibitively computational resources. On the other hand, different positionings and rotations of methanol on the cluster would lead to different conformations and therefore to different energies. The present work consists of an analysis of physisorbed methanol on MgO, varying the spatial orientations.