Interaction of Aromatic Molecules with Forsterite: Accuracy of the Periodic DFT-D4 Method

Abstract

Density functional theory (DFT) has provided deep atomic-level insights into the adsorption behavior of aromatic molecules on solid surfaces. However, modeling the surface phenomena of large molecules on mineral surfaces with accurate plane wave methods (PW) can be orders of magnitude more computationally expensive than localized atomic orbitals (LCAO) methods. In the present work, we propose a less costly approach based on the DFT-D4 method (PBE-D4), using LCAO, to study the interactions of aromatic molecules with the {010} forsterite (Mg 2 SiO 4 ) surface for their relevance in astrochemistry. We studied the interaction of benzene with the pristine {010} forsterite surface and with transition-metal cations (Fe 2+ and Ni 2+ ) using PBE-D4 and a vdW-inclusive density functional (Dion, Rydberg, Schröder, Langreth, and Lundqvist (DRSLL)) with LCAO methods. PBE-D4 shows good agreement with coupled-cluster methods (CCSD(T)) for the binding energy trend of cation complexes and with PW methods for the binding energy of benzene on the forsterite surface with a difference of about 0.03 eV. The basis set superposition error (BSSE) correction is shown to be essential to ensure a correct estimation of the binding energies even when large basis sets are employed for single-point calculations of the optimized structures with smaller basis sets. We also studied the interaction of naphthalene and benzocoronene on pristine and transition-metal-doped {010} forsterite surfaces as a test case for PBE-D4. Yielding results that are in good agreement with the plane wave methods with a difference of about 0.02–0.17 eV, the PBE-D4 method is demonstrated to be effective in unraveling the binding structures and the energetic trends of aromatic molecules on pristine and transition-metal-doped forsterite mineral surfaces. Furthermore, PBE-D4 results are in good agreement with its predecessor PBE-D3(BJM) and with the vdW-inclusive density functionals, as long as transition metals are not involved. Hence, PBE-D4/CP-DZP has been proven to be a robust theory level to study the interaction of aromatic molecules on mineral surfaces.

Adsorption of Polycyclic Aromatic Hydrocarbons and C60 onto Forsterite: C–H Bond Activation by the Schottky Vacancy

“…However, this difference is not significant considering the accuracy of the functional used. 22 Once the transition metal coordinates with an aromatic molecule such as naphthalene, the Ni point defect in the M1 site is stabilized by 0.30 and 1.61 eV with respect to M2 and M3. The table in Figure 2 shows bond distances and angles for Ni-[010]-fo, which are in close agreement with those for Fe-[010]-fo and [010]-fo.…”

“…All models have a 19 × 17.94 × 35.20 Å (α = β = γ = 90°) supercell (4 × 3 × 1) with a slab thickness of 9.25 Å. The [010] slab surfaces were generated by cutting the optimized bulk of forsterite from a prior study 22 using the METADISE code. 38 The bottom layers (about 4 Å thickness) have been constrained during the whole optimization procedure, whereas the topmost layers were allowed to relaxed unconstrainedly.…”

“…The slab models were optimized using periodic density functional theory implemented in the SIESTA code, 42 which makes use of localized atomic orbitals basis sets (LCAO). The details of the method have been described as well as benchmarked in a prior work 22 and are summarized here.…”

“… 49 An electric field along the z -axis is set to override the resulting dipole moment along the z -axis of the slabs during the optimization procedure. In a prior study, 22 PBE-D4/DZP was proven to be a robust theory level to study the interaction of aromatic molecules on mineral surfaces.…”

“…Only a few studies have addressed the interaction of organic species with a forsterite surface using first-principle methods. 22 − 24 …”