Role of Tensorial Electronic Friction in Energy Transfer at Metal Surfaces

Askerka, Mikhail; Maurer, Reinhard J.; Batista, Víctor S.; Tully, John C.

doi:10.1103/physrevlett.116.217601

Cited by 106 publications

(126 citation statements)

References 46 publications

(67 reference statements)

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“…Our lifetimes obtained for the internal (r) mode are probably overestimated in the independent-atom LDFA approach [38], while those of the Z mode are probably somewhat underestimated [37]. Frictional approaches beyond the original independent atom LDFA have been suggested [38][39][40][41]. Still, the LDFA accounts for multimode electronic damping in a reasonable and parameter-free way.…”

Section: A Vibrational Lifetimesmentioning

confidence: 71%

Femtosecond-laser induced dynamics of CO on Ru(0001): Deep insights from a hot-electron friction model including surface motion

et al. 2016

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A Langevin model accounting for all six molecular degrees of freedom is applied to femtosecond-laser induced, hot-electron driven dynamics of Ru(0001)(2 × 2):CO. In our molecular dynamics with electronic friction approach, a recently developed potential energy surface based on gradient-corrected density functional theory accounting for van der Waals interactions is adopted. Electronic friction due to the coupling of molecular degrees of freedom to electron-hole pairs in the metal are included via a local density friction approximation, and surface phonons by a generalized Langevin oscillator model. The action of ultrashort laser pulses enters through a substrate-mediated, hot-electron mechanism via a time-dependent electronic temperature (derived from a two-temperature model), causing random forces acting on the molecule. The model is applied to laser induced lateral diffusion of CO on the surface, "hot adsorbate" formation, and laser induced desorption. Reaction probabilities are strongly enhanced compared to purely thermal processes, both for diffusion and desorption. Reaction yields depend in a characteristic (nonlinear) fashion on the applied laser fluence, as well as branching ratios for various reaction channels. Computed two-pulse correlation traces for desorption and other indicators suggest that aside from electron-hole pairs, phonons play a non-negligible role for laser induced dynamics in this system, acting on a surprisingly short time scale. Our simulations on precomputed potentials allow for good statistics and the treatment of long-time dynamics (300 ps), giving insight into this system which hitherto has not been reached. We find generally good agreement with experimental data where available and make predictions in addition. A recently proposed laser induced population of physisorbed precursor states could not be observed with the present low-coverage model.

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Section: A Vibrational Lifetimesmentioning

confidence: 71%

Femtosecond-laser induced dynamics of CO on Ru(0001): Deep insights from a hot-electron friction model including surface motion

et al. 2016

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“…18,[42][43] Despite these successes, LDFA has been continuously questioned in describing non-adiabatic interactions between molecules and metal surfaces, because the atomic friction coefficients intrinsically lack the directional dependence and molecular anisotropy that arises from the electron-nuclear coupling of a many-electron system described in a realistic potential. 35,[44][45][46][47][48] In principle, the full-rank EFT can be obtained by the first-order time-dependent perturbation theory (TDPT) based on KS orbitals of DFT that fully accounts for the electronic structure of molecule-surface system. 21 Very recently, Meyer et al [52][53] and we [54][55] have independently discussed the influence of mode specific electronic frictions on dissociative sticking and state-to-state scattering probabilities of N2 and H2 on metal surfaces, both using a neural network (NN) representation but with different approaches to describe the symmetry properties of EFT.…”

Section: Introductionmentioning

confidence: 99%

Symmetry-Adapted High Dimensional Neural Network Representation of Electronic Friction Tensor of Adsorbates on Metals

2019

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Nonadiabatic effects in chemical reaction at metal surfaces, due to excitation of electron-hole pairs, stand at the frontier of the studies of gas-surface reaction dynamics.However, the first principles description of electronic excitation remains challenging.In an efficient molecular dynamics with electronic friction (MDEF) method, the nonadiabatic couplings are effectively included in a so-called electronic friction tensor (EFT), which can be computed from first-order time-dependent perturbation theory (TDPT) in terms of density functional theory (DFT) orbitals. This second-rank tensor depends on adsorbate position and features a complicated transformation with regard to the intrinsic symmetry operations of the system. In this work, we develop a new symmetry-adapted neural network representation of EFT, based on our recently proposed embedded atom neural network (EANN) framework. Inspired by the derivation of the nonadiabatic coupling matrix, we represent the tensorial friction by the first and second derivatives of multiple outputs of NNs with respect to atomic Cartesian coordinates. This rigorously preserves the positive semidefiniteness, directional property, and correct symmetry-equivariance of EFT. Unlike previous methods, our new approach can readily include both molecular and surface degrees of freedom, regardless of the type of surface. Tests on the H2+Ag(111) system show that this approach yields an accurate, efficient, and continuous representation of EFT, making it possible to perform large scale TDPT-based MDEF simulations to study both adiabatic and nonadiabatic energy dissipation in a unified framework.

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“…In addition, recently predicted coupling between the S and ES modes due to the off-diagonal elements of the friction tensor [62] can contribute to the discrepancies.…”

Section: Prl 117 186101 (2016) P H Y S I C a L R E V I E W L E T T Ementioning

confidence: 99%

The Calisthenics of Surface Femtochemistry

Petek

2016

Physics

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Hot carriers at metal surfaces can drive nonthermal reactions of adsorbates. Characterizing nonequilibrium statistics among various degrees of freedom in an ultrafast time scale is crucial to understand and develop hot carrier-driven chemistry. Here we demonstrate multidimensional vibrational dynamics of carbon monoxide (CO) on Cu(100) along hot-carrier induced desorption studied by using time-resolved vibrational sum-frequency generation with phase-sensitive detection. Instantaneous frequency and amplitude of the CO internal stretching mode are tracked with a subpicosecond time resolution that is shorter than the vibrational dephasing time. These experimental results in combination with numerical analysis based on Langevin simulations enable us to extract nonequilibrium distributions of external vibrational modes of desorbing molecules. Superstatistical distributions are generated with modedependent frictional couplings in a few hundred femtoseconds after hot-electron excitation, and energy flow from hot electrons and intermode anharmonic coupling play crucial roles in the subsequent evolution of the non-Boltzman distributions. DOI: 10.1103/PhysRevLett.117.186101 Hot-carrier induced surface reaction of adsorbates on metal is triggered nonthermally by high-temperature electrons, which are generated by irradiation of metal with an intense femtosecond laser pulse [1][2][3][4][5][6][7][8][9][10][11][12][13] or by excitation of the localized surface plasmon of metallic nanoparticles [14][15][16][17]. Ultrafast energy transfer from electrons in metal to adsorbate nuclear degrees of freedom (DOF) via nonadiabatic coupling [18][19][20][21][22][23][24][25] is of fundamental importance because it induces novel surface reactions [14,26,27].Despite extensive studies at flat metal surfaces over decades [26], our understanding of the ultrafast energy flow during hot-carrier induced reactions is still in its infancy. Earlier two-pulse correlation studies [1,[3][4][5][8][9][10][11]28] have specified the time scale of reactions and provided rich information on energy partitioning in desorption by product state analysis but were incapable of probing vibrational dynamics. Ultrafast time-resolved vibrational spectroscopy, particularly probing the internal stretching mode (S mode) of diatomic adsorbates [12,29,30], has been used to track excitation of external vibrational modes: frustrated translation (FT), frustrated rotation (FR), and external stretch (ES) modes. While the frequency shift of the S mode is dominated by coupling with the FT mode under moderate excitation [31][32][33][34][35], intense fs pulse excitation leads to larger S-mode frequency shifts due to hot-carrier driven FR mode excitation; thus, the FR mode was considered to trigger lateral hopping [12] and/or desorption of adsorbates [36,37]. Because the time resolution of the time-resolved vibrational sum-frequency generation (TR-VSFG) studies is inherently limited by an S-mode dephasing time (∼1 ps), it has not been possible to clarify the dynamics in the sub-p...

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Role of Tensorial Electronic Friction in Energy Transfer at Metal Surfaces

Cited by 106 publications

References 46 publications

Femtosecond-laser induced dynamics of CO on Ru(0001): Deep insights from a hot-electron friction model including surface motion

Femtosecond-laser induced dynamics of CO on Ru(0001): Deep insights from a hot-electron friction model including surface motion

Symmetry-Adapted High Dimensional Neural Network Representation of Electronic Friction Tensor of Adsorbates on Metals

The Calisthenics of Surface Femtochemistry

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