The Key Role of van der Waals Interactions in MPc/Au(111) (M = Co, Fe, H₂) Systems Based on First-Principles Calculations

Abstract

First-principles calculations for metal−phthalocyanines (MPc, M = Co, Fe, H 2 ) adsorbed on Au(111) surfaces with LDA, PW91, and optB86b-vdW functionals are performed. The adsorption energies, adsorption distances, potential energy surfaces, electron transfer properties, and the migration barriers are calculated and compared with the reported experimental data. Our results show that, while PW91 functional is obviously not suitable for MPc/Au(111) systems due to its intrinsic short comings, LDA and optB86b-vdW functionals give more reliable results. The optB86b-vdW functional has overall the best performance among the three functionals, which indicates that the van der Waals interactions play key roles in such adsorption systems.

Surface chemistry of porphyrins and phthalocyanines

“…Similar findings have been reported for CoPc (and FePc) on Ag(1 0 0), for which DFT calculations indicated a strong hybridization of the d z 2 orbital at the metal center with Ag-sp z states [242]. A comprehensive theoretical study of CoPc (along with FePc and 2HPc) on Au (1 1 1), which emphasizes the central role of van der Waals interactions, was performed by Li et al [547].…”

“…39e, configuration I) [248]. Besides donation of electron density from the substrate to the Co ion, there is back donation from the Pc ligand to the substrate [199] (as has also been predicted for CoPc and FePc on Au(1 1 1) [547]). Comparison of the calculated adsorption energies with and without inclusion of van der Waals contributions, 568 and 135 kJ/mol, respectively, demonstrated that a realistic description of the bond situation cannot be achieved when only the covalent contributions are taken into account.…”

“…Theoretical treatment of the surface chemical bond of porphyrins and phthalocyanines with DFT methods is hampered by the (presumably) large contribution of van der Waals dispersive interactions, which are not adequately described by standard DFT. However, there is an increasing awareness of this issue, and various approximate corrections have been introduced [544][545][546] and successfully applied to the adsorption of porphyrins [20,365,436] and phthalocyanines [248,330,341,360,547].…”

Piezoelectric property of bundled peptide nanotubes stapled by bis‐cyclic‐β‐peptide

“…The positive surface potential should be therefore ascribable to the net dipole directing to the opposite side of the gold substrate. There may be two factors contributing to the dipole generation, where one is the specific interaction of the amide bonds with the gold substrate and the other is the adsorption of aromatic groups on gold surface . The former amide dipoles direct parallel to surface, which should contribute less to the vertical dipole generation to the surface.…”

Theoretical exploration of the forces governing the interaction between gold–phthalocyanine and gold surface clusters

“…9,10 One of the most studied systems is the modication of gold surface with various types of MPcs through direct adsorption on the surface 9,[11][12][13][14] explored by a variety of surface techniques, mainly scanning tunnelling microscopy (STM). 4,[14][15][16] Also, there are extensive experimental and theoretical studies regarding rst row transition metals atoms modifying Pcs, such as Fe, Co, Cu, 10,[13][14][15][16][17][18][19][20][21][22][23][24][25][26] but little work has been done using an Au atom coordinating the Pc. [27][28][29] Also, there are theoretical works about the AuPc using DFT in which it has been shown that the spin-density pattern is fully delocalized with an oscillating behaviour.…”