Excited-state potential-energy surfaces of metal-adsorbed organic molecules from linear expansion Δ-self-consistent field density-functional theory (ΔSCF-DFT)

Abstract

Accurate and efficient simulation of excited state properties is an important and much aspired cornerstone in the study of adsorbate dynamics on metal surfaces. To this end, the recently proposed linear expansion Δ-self-consistent field method by Gavnholt et al. [Phys. Rev. B 78, 075441 (2008)] presents an efficient alternative to time consuming quasi-particle calculations. In this method, the standard Kohn-Sham equations of density-functional theory are solved with the constraint of a non-equilibrium occupation in a region of Hilbert-space resembling gas-phase orbitals of the adsorbate. In this work, we discuss the applicability of this method for the excited-state dynamics of metal-surface mounted organic adsorbates, specifically in the context of molecular switching. We present necessary advancements to allow for a consistent quality description of excited-state potential-energy surfaces (PESs), and illustrate the concept with the application to Azobenzene adsorbed on Ag(111) and Au(111) surfaces. We find that the explicit inclusion of substrate electronic states modifies the topologies of intra-molecular excited-state PESs of the molecule due to image charge and hybridization effects. While the molecule in gas phase shows a clear energetic separation of resonances that induce isomerization and backreaction, the surface-adsorbed molecule does not. The concomitant possibly simultaneous induction of both processes would lead to a significantly reduced switching efficiency of such a mechanism.

Molecular Topology and the Surface Chemical Bond: Alternant Versus Nonalternant Aromatic Systems as Functional Structural Elements

“…NEXAFS simulations were performed using on-the-fly generated USPPs and the CASTEP module ELNES [57] and the transition-potential approach [58,59]. For more details on the computational settings, analysis, and implementation, see the Supplemental Material [44] and Diller et al [60] as well as Maurer and Reuter [61]. Furthermore, the Supplemental Material [44] contains additional NEXAFS simulations obtained by a more approximate method.…”

Molecule–Metal Bond of Alternant versus Nonalternant Aromatic Systems on Coinage Metal Surfaces: Naphthalene versus Azulene on Ag(111) and Cu(111)

“…[38][39] For more details on the computational settings and analysis see the SI and Diller et al 40 For more details on the implementation of the molecular orbital projection employed in Figure 9, see Maurer and Reuter. 41…”

Ab initiotensorial electronic friction for molecules on metal surfaces: Nonadiabatic vibrational relaxation

“…[86][87][88][89] Here, we employ ground-state KS states to calculate nonadiabatic couplings disregarding any final state effects or excited state screening. However, there may be simple ways to go beyond this approximation by employing effective excited-state screening methods such as constrained DFT, 90,91 the Delta-self-consistent-field-DFT (∆SCF-DFT) 92 and related approaches, 93,94 or the Slater transition potential method. 95,96 The matrix elements in eq.…”