We assess the accuracy of vibrational damping rates of diatomic adsorbates on metal surfaces as calculated within the local-density friction approximation (LDFA). An atoms-in-molecules (AIM) type charge partitioning scheme accounts for intramolecular contributions and overcomes the systematic underestimation of the nonadiabatic losses obtained within the prevalent independent-atom approximation. The quantitative agreement obtained with theoretical and experimental benchmark data suggests the LDFA-AIM scheme as an efficient and reliable approach to account for electronic dissipation in ab initio molecular dynamics simulations of surface chemical reactions. A central challenge in energy and catalysis applications is to transfer energy specifically into those degrees of freedom that actually drive a desired surface chemical reaction-and to keep this energy in these degrees of freedom for a sufficiently long time. In this transfer of energy, losses due to electronic nonadiabaticity can be an important dissipation channel [1,2]. In aiming to assess this channel for systems of technological interest, predictive-quality calculations would be a valuable addition to experimental endeavors. Especially for chemical reactions at frequently employed metal substrates, however, a corresponding methodology has not yet been well established. To date, most accurate solutions of the full nuclear-electron wave function are restricted to systems of the complexity level of gas-phase H 2 þ [3]. In the limit of weak nonadiabaticity as pertinent to electron-hole (eh) pair excitations during adsorbate dynamics on metal surfaces, less rigorous approaches rely on mixed quantum-classical dynamics. The imposed computational burden nevertheless still restricts their practical use to simple metals and subpicosecond time scales [4,5], to symmetric adsorbate trajectories [6,7], or to only qualitative accounts of the metal electronic structure [8,9]. Presently, it is thus only the concept of electronic friction [10-13] and its incorporation into classical molecular dynamics (MD) simulations on the Born-Oppenheimer potential energy surface (PES) V PES [14-21] that promises predictive-quality and material-specific trajectory calculations over an extended period of time. Particularly the local-density friction approximation (LDFA) [16,22] and for molecular adsorbates an additional independent-atom approximation (IAA) [16-18] provide a further decrease in computational cost. This has allowed for first accounts of electronic nonadiabaticity in large-scale MD simulations based on a first-principles and high-dimensional description of the underlying PES-either interpolated [16-19] or even evaluated on-the-fly within ab initio MD simulations [20,21]. However, due to the drastic simplifications introduced with the IAA, the validity of the LDFA formalism for molecular adsorbates per se has been controversially discussed [16,23,24]. By construction, the IAA does not resolve the electronic structure of the interacting molecule-surface system and in particula...

Over the last two decades, several classes of highly ion-conductive SSEs have been developed which reach or surpass current liquid-state electrolyte conductivity. [5,6] Yet, no ASSB paying in on the above promises has been developed to date. This is mainly due to mechanochemical, chemical, and electrochemical stability issues and interfacial processes that have severely compromised any proposed cell's lifetime. [7][8][9][10][11] While many SSE material inherent (mechano-)chemical processing issues seem amenable to modern engineering approaches, [12][13][14][15][16][17][18][19] the situation is less bright regarding the control of interfacial chemical and electrochemical stability (especially when featuring a LMA), as well as ionic and electronic transport quantities across these interfaces. A hitherto missing deep understanding of the structural, chemical, and physical properties of the buried solid-solid interfaces inside ASSBs at the atomic level is required to overcome these performance limiting interfacial issues.The most studied interfacial properties so far are contact stability and dendrite nucleation and growth. [20][21][22] Both issues are accentuated for LMA/SSE interfaces. In a first approximation, interfacial stability can be traced back to the Dendrite formation and growth remains a major obstacle toward highperformance all solid-state batteries using Li metal anodes. The ceramic Li (1+x) Al (x) Ti (2−x) (PO 4 ) 3 (LATP) solid-state electrolyte shows a higher than expected stability against electrochemical decomposition despite a bulk electronic conductivity that exceeds a recently postulated threshold for dendrite-free operation. Here, transmission electron microscopy, atom probe tomography, and first-principles based simulations are combined to establish atomistic structural models of glass-amorphous LATP grain boundaries. These models reveal a nanometer-thin complexion layer that encapsulates the crystalline grains. The distinct composition of this complexion constitutes a sizable electronic impedance. Rather than fulfilling macroscopic bulk measures of ionic and electronic conduction, LATP might thus gain the capability to suppress dendrite nucleation by sufficient local separation of charge carriers at the nanoscale.

Conversion of energy at the gas-solid interface lies at the heart of many industrial applications such as heterogeneous catalysis. Dissipation of parts of this energy into the substrate bulk drives the thermalization of surface species, but also constitutes a potentially unwanted loss channel. At present, little is known about the underlying microscopic dissipation mechanisms and their (relative) efficiency. At metal surfaces, prominent such mechanisms are the generation of substrate phonons and the electronically non-adiabatic excitation of electron-hole pairs. In recent years, dedicated surface science experiments at defined single-crystal surfaces and predictive-quality firstprinciples simulations have increasingly been used to analyze these dissipation mechanisms in prototypical surface dynamical processes such as gas-phase scattering and adsorption, diffusion, vibration, and surface reactions. In this topical review we provide an overview of modeling approaches to incorporate dissipation into corresponding dynamical simulations starting from coarsegrained effective theories to increasingly sophisticated methods. We illustrate these at the level of individual elementary processes through applications found in the literature, while specifically highlighting the persisting difficulty of gauging their performance based on experimentally accessible observables.

Helium spin echo experiments combined with ab initio-based Langevin molecular dynamics simulations are used to quantify the adsorbate-substrate coupling during the thermal diffusion of Na atoms on Cu(111). An analysis of trajectories within the local density friction approximation allows the contribution from electronhole pair excitations to be separated from the total energy dissipation. Despite the minimal electronic friction coefficient of Na and the relatively small mass mismatch to Cu promoting efficient phononic dissipation, about (20 ± 5)% of the total energy loss is attributable to electronic friction. The results suggest a significant role of electronic non-adiabaticity in the rapid thermalization generally relied upon in adiabatic diffusion theories.

SummaryThe electronic and structural properties of oligo- and polythiophenes that can be used as building blocks for molecular electronic devices have been studied by using periodic density functional theory calculations. We have in particular focused on the effect of substituents on the electronic structure of thiophenes. Whereas singly bonded substituents, such as methyl, amino or nitro groups, change the electronic properties of thiophene monomers and dimers, they hardly influence the band gap of polythiophene. In contrast, phenyl-substituted polythiophenes as well as vinyl-bridged polythiophene derivatives exhibit drastically modified band gaps. These effects cannot be explained by simple electron removal or addition, as calculations for charged polythiophenes demonstrate.

We present a perturbation approach rooted in time-dependent density-functional theory to calculate electron-hole (e-h) pair excitation spectra during the nonadiabatic vibrational damping of adsorbates on metal surfaces. Our analysis for the benchmark systems CO on Cu(100) and Pt(111) elucidates the surprisingly strong influence of rather short electronic coherence times. We demonstrate how in the limit of short electronic coherence times, as implicitly assumed in prevalent quantum nuclear theories for the vibrational lifetimes as well as electronic friction, band structure effects are washed out. Our results suggest that more accurate lifetime or chemicurrentlike experimental measurements could characterize the electronic coherence. DOI: 10.1103/PhysRevLett.119.176808 The tortuous ways in which kinetic and chemical energy is transferred between adsorbates and substrate atoms fundamentally govern the dynamics of surface chemical reactions, for instance, in the context of heterogeneous catalysis or advanced deposition techniques. For metal substrates, the two main energy dissipation mechanisms in this regard are the adsorbate interaction with lattice vibrations, i.e., substrate phonons, and the excitation of electronhole (e-h) pairs. The latter are attributable to the nonadiabatic coupling of nuclear motion to the substrate electronic degrees of freedom (d.o.f.) and seem to be substantial in order to rationalize an increasing number of experimental findings [1,2]. Important steps towards an accurate, yet efficient firstprinciples-based modeling of the energy uptake into phononic d.o.f. have recently been taken [3][4][5][6][7][8][9][10]. In contrast, the explicit description of e-h pair excitations and corresponding nonadiabatic couplings directly from first principles still poses a formidable challenge.In this regard, electronic friction theory (EFT) [11,12] has become a popular workhorse to effectively capture the effects of such nonadiabatic energy loss on the adsorbate dynamics in a computationally convenient way [13][14][15][16][17][18][19]. Inspired by vibrational lifetimes obtained via response theory [20] or Fermi's golden rule in the nuclear system [21], a Langevin equation for the nuclei emerges from a semiclassical picture implying complete electronic decoherence in terms of the Markov approximation [12]. This approach thus avoids an explicit propagation of the electron dynamics and concomitant ultrafast time scales by coarse-graining the effects into electronic friction forces linear in nuclear velocities. This enables an efficient combination even with density-functional theory (DFT) based ab initio molecular dynamics (AIMD) simulations on high-dimensional potential energy surfaces as required for surface dynamical studies [15,22,23].Independent of the particular recipe employed to obtain the electronic friction coefficients [12,14,17,20,24,25], however, the downside of the coarse-graining of the electron dynamics is that it precludes a more fundamental understanding of the underlying e-h pair excit...

In article number 2100707, Christoph Scheurer and co‐workers stabilize solid state electrolyte grains against Li dendrite nucleation and growth with a nanometer thin complexion. This naturally forming encapsulating layer serves as an effective electronic barrier while being permeable for Li ions. Future interfacial engineering could exploit a corresponding local separation of electronic and ionic flux at solid‐solid interfaces for rational advances in all‐solid‐state batteries.