Ab initio Study on Adsorption of Transition-Metal Phthalocyanine on a Quasi-One-Dimensional Metallic Surface, In/Si(111)-4x1

Abstract

Transition-metal containing metal phthalocyanine (MPc) molecules are representative molecular magnets and their adsorption on two-dimensional metallic surfaces has been extensively studied. In/Si(111)-4x1 is a prototypical quasi-one-dimensional metallic surface made up of alternating In nanowires and Si Seiwatz chains. Here, we investigated the adsorption of MPc (M = Mn, Fe, Co) on In/Si(111)-4x1 using density functional theory calculations. We found that there are three locally stable adsorption sites of MPc, two on In nanowires and one on Seiwatz chains. Also, the stable orientation of MPc is different depending on adsorption sites. Among three MPc's, MnPc are found to carry a finite magnetic moment of 1.6 similar to 2.1 mu(B) in its three almost-degenerate adsorption structures. The interaction between MPc molecules and the In/Si(111)-4x1 surface turns out to occur via the charge transfer, and the charge transfer channel varies for different adsorption sites: Transition-metal 3d(z)(2) and two N 2p(z) orbitals on In nanowires vs. four N 2p(z) orbitals on Seiwatz chains.