Correction to "Screening Mixed-Metal Sn2M(III)Ch2X3 Chalcohalides for Photovoltaic Applications".

[This corrects the article DOI: 10.1021/acs.chemmater.3c01629.].

Bonding character of intermediates in on-surface Ullmann reactions revealed with energy decomposition analysis.

On-surface synthesis has become a thriving topic in surface science. The Ullmann coupling reaction is the most applied synthetic route today, but the nature of the organometallic intermediate is still under discussion. We investigate the bonding nature of prototypical intermediate species (phenyl, naphthyl, anthracenyl, phenanthryl, and triphenylenyl) on the Cu(111) surface with a combination of plane wave and atomic orbital basis set methods using density functional theory calculations with periodic boundary conditions. The surface bonding is shown to be of covalent nature with a polarized shared-electron bond supported by π-back donation effects using energy decomposition analysis for extended systems (pEDA). The bond angle of the intermediates is determined by balancing dispersion attraction and Pauli repulsion between adsorbate and surface. The latter can be significantly reduced by adatoms on the surface. We furthermore investigate how to choose computational parameters for pEDA of organic adsorbates on metal surfaces efficiently and show that bonding interpretation requires consistent choice of the density functional.

Temperature-dependent Li vacancy diffusion in Li4Ti5O12 by means of first principles molecular dynamic simulations.

Lithium-ion batteries (LIBs) are a key electrochemical energy storage technology for mobile applications. In this context lithium titanate (LTO) is an attractive anode material for fast-charging LIBs and solid-state batteries (SSBs). The Li ion transport within LTO has a major impact on the performance of the anode in LIBs or SSBs. The Li vacancy diffusion in lithium-poor Li4Ti5O12 can take place either via 8ainit ↔ 16c ↔ 8afinal or a 8ainit ↔ 16c ↔ 48f ↔ 16dfinal diffusion path. To gain a more detailed understanding of the Li vacancy transport in LTO, we performed first principles molecular dynamics (FPMD) simulations in the temperature range from 800 K to 1000 K. To track the Li vacancies through the FPMD simulations, we introduce a method to distinguish the positions of multiple (Li) vacancies at each time. This method is used to characterize the diffusion path and the number of different diffusion steps. As a result, the majority of Li vacancy diffusion steps occur along the 8ainit ↔ 16c ↔ 8afinal. Moreover, the results indicate that the 16d Wyckoff position is a trapping site for Li vacancies. The dominant 8ainit ↔ 16c ↔ 8afinal path appears to compete with its back diffusion, which can be identified by the lifetime t16c of the 16c site. Our studies show that for t16c < 100 fs the back diffusion dominates, whereas for 100 fs ≤ t16c < 200 fs the 8ainit ↔ 16c ↔ 8afinal path dominates. In addition, the temperature-independent pre-factor D0 of the diffusion coefficient, as well as the attempt frequency Γ0 and the activation energy EA in lithium-poor LTO have been determined to be D0 = 1.5 × 10-3 cm2 s-1, as well as Γ0 = 6.6 THz and EA = 0.33 eV.

Influence of the POuN4-u structural units on the formation energies and transport properties of lithium phosphorus oxynitride: a DFT study.

The potential of mobile applications for digital networking is constantly increasing. A key challenge is to ensure a reliable and long-term power supply. One possible solution is the use of all-solid-state thin-film lithium batteries which use amorphous lithium phosphorus oxynitride (LIPON) as solid electrolyte. It is well known that the electrochemical properties of this material are related to the amorphous state, which correlates with the nitrogen content. Due to the difficulty of calculating amorphous structures using first principles methods, three different LIPON structure models are considered in this study and the influence of the anion POuN4-u sublattice on the Li vacancy and Li interstitial formation as well as on the lithium ion transport is highlighted. While for all three model systems the migration energies of the energetically preferred Li vacancies increase with increasing complexity of the anion POuN4-u sublattice only slightly from 0.38 eV to 0.55 eV, the migration energies for the energetically preferred Li interstitials decrease with increasing complexity of the anion POuN4-u sublattice from 0.68 eV to 0.38 eV. Thus, it was found that the energetically preferred lithium ion (Li vacancy and Li interstitial ion) transport mechanism in LIPON can be explained on the basis of the present POuN4-u structural units. In the presence of isolated PON3x- tetrahedra or periodic PO2N2 chains, the lithium vacancy diffusion dominates, whereas in the presence of periodic POuN4-u planes, the lithium interstitial diffusion becomes dominant.

Uncertainty of exchange-correlation functionals in density functional theory calculations for lithium-based solid electrolytes on the case study of lithium phosphorus oxynitride.

Amorphous lithium phosphorus oxynitride (LIPON) has emerged as a promising solid electrolyte for all-solid-state thin-film lithium batteries. In this context, the use of theoretical modeling to characterize, understand, or screen material properties is becoming increasingly important to complement experimental analysis or elucidate features at atomistic level that are difficult to obtain through experimental studies. Density functional theory (DFT) is the method of choice for quantum mechanical material modeling at the atomistic scale. The current state of the art represents DFT values, such as the formation or migration energies relevant for bulk phase of materials, as absolute numbers. Estimating the accuracy or fluctuation range of the different density functionals is challenging. In order to investigate the thermodynamic and kinetic properties of LIPON by DFT, an approach to describe the fluctuation range caused by the choice of the exchange-correlation (XC) functional is developed. Three different model systems were chosen to characterize various structural features of amorphous LIPON, which are distinguished by the cross-linking of the POu N4-u -structural units. The uncertainty U is introduced as a parameter describing the fluctuation range of energy values. The uncertainty approach does not determine the accuracy of DFT results, but rather a fluctuation range in the DFT results without the need for a reference value from a higher level of theory or experiment. The uncertainty was determined for both the thermodynamic Li-vacancy formation energies and the kinetic Li-vacancy migration energies in LIPON. We assume that the uncertainty approach can be applied to different material systems with different density functionals.

Surface-controlled reversal of the selectivity of halogen bonds.

Intermolecular halogen bonds are ideally suited for designing new molecular assemblies because of their strong directionality and the possibility of tuning the interactions by using different types of halogens or molecular moieties. Due to these unique properties of the halogen bonds, numerous areas of application have recently been identified and are still emerging. Here, we present an approach for controlling the 2D self-assembly process of organic molecules by adsorption to reactive vs. inert metal surfaces. Therewith, the order of halogen bond strengths that is known from gas phase or liquids can be reversed. Our approach relies on adjusting the molecular charge distribution, i.e., the σ-hole, by molecule-substrate interactions. The polarizability of the halogen and the reactiveness of the metal substrate are serving as control parameters. Our results establish the surface as a control knob for tuning molecular assemblies by reversing the selectivity of bonding sites, which is interesting for future applications.

Adsorption Structure of Mono- and Diradicals on a Cu(111) Surface: Chemoselective Dehalogenation of 4-Bromo-3″-iodo- p-terphenyl.

Selectivity is a key parameter for building customized organic nanostructures via bottom-up approaches. Therefore, strategies are needed that allow connecting molecular entities at a specific stage of the assembly process in a chemoselective manner. Studying the mechanisms of such reactions is the key to apply these transformations for the buildup of organic nanostructures on surfaces. Especially, the knowledge about the precise adsorption geometry of intermediates at different stages during the reaction process and their interactions with surface atoms or adatoms is of fundamental importance, since often catalytic processes are involved. We show the selective dehalogenation of 4-bromo-3″-iodo- p-terphenyl on the Cu(111) surface using bond imaging atomic force microscopy with CO-functionalized tips. The deiodination and debromination reactions are triggered either by heating or by locally applying voltage pulses with the tip. We observed a strong hierarchical behavior of the dehalogenation with respect to temperature and voltage. In connection with first-principles simulations we can determine the orientation and position of the pristine molecules as well as adsorbed mono/diradicals and the halogens. We find that the isolated radicals are chemisorbed to Cu(111) top sites, which are lifted by 16 pm ( meta-position) and 32 pm ( para-position) from the Cu surface plane. This leads to a strongly twisted and bent 3D adsorption structure. After heating, different types of dimers are observed whose molecules are either bound to surface atoms or connected via Cu adatoms. Such knowledge about the intermediate geometry and its interaction with the surface will open the way to rationally design syntheses on surfaces.