Ari Paavo Seitsonen

Ecole Normale Supérieure de Paris | ENS · Département de Chimie

We present ab initio simulations of a large system of 2400 particles of molten NaCl to investigate the behavior of collective mode dispersion beyond the hydrodynamic regime. In particular, we aim to explain the unusually strong increase in the apparent speed of sound with wave number, which significantly exceeds the typical positive sound dispersio...

Transmetalation represents an appealing strategy toward fabricating and tuning functional metal–organic polymers and frameworks for diverse applications. In particular, building two-dimensional metal–organic and organometallic networks affords versatile nanoarchitectures of potential interest for nanodevices and quantum technology. The controlled r...

Graphyne (GY) and graphdiyne (GDY)‐based monolayers represent the next generation 2D carbon‐rich materials with tunable structures and properties surpassing those of graphene. However, the detection of band formation in atomically thin GY/GDY analogues has been challenging, as both long‐range order and atomic precision have to be fulfilled in the s...

Complex phenomena characterize the intercalation of ions inside stratified crystals. Their comprehension is crucial in view of exploiting the intercalation mechanism to change the transport properties of the crystal or...

Change of conformation or polarization of molecules is an expression of their functionality. If the two correlate, electric fields can change the conformation. In the case of endofullerene single‐molecule magnets the conformation is linked to an electric and a magnetic dipole moment, and therefore magnetoelectric effects are envisoned. The interfac...

Contaminants sequestration by iron oxides are of particular relevance in environmental chemistry and Fourier Transform Infrared (FTIR) Spectroscopy in Attenuated Total Reflectance (ATR) mode is used in this study to...

The growth of graphene and hexagonal boron nitride on hot transition metal surfaces involves the adsorption of precursor molecules, and their dissociation and assembly into two-dimensional honeycomb lattices. In a recent account it was found that h-BN may be distilled on a rhodium metal surface, which yields higher quality h-BN [Cun et al., ACS Nan...

One of the fundamental quantities in dynamics of the liquid state, the adiabatic speed of sound cs\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$c_s$$\end{document}, i...

Graphyne (GY) and graphdiyne (GDY)-based materials represent an intriguing class of two-dimensional (2D) carbon-rich networks with tunable structures and properties surpassing those of graphene. However, the challenge of fabricating atomically well-defined crystalline GY/GDY-based systems largely hinders detailed electronic structure characterizati...

Water is an ubiquitous liquid that has several exotic and anomalous properties. Despite its apparent simple chemical formula, its capability of forming a dynamic network of hydrogen bonds leads to a rich variety of physics. Here we study the vibrations of water using molecular dynamics simulations, mainly concentrating on the Raman and infrared spe...

Defect engineering in two-dimensional materials expands the realm of their applications in catalysis, nanoelectronics, sensing, and beyond. As limited tools are available to explore nanoscale functional properties in non-vacuum environments, theoretical modeling provides some invaluable insight into the effect of local deformations to deepen the un...

Water is an ubiquitous liquid that has several exotic and anomalous properties. Despite its apparent simple chemical formula, its capability of forming a dynamic network of hydrogen bonds leads to a rich variety of physics. Here we study the vibrations of water using molecular dynamics simulations, mainly concentrating on the Raman and infrared spe...

We report an ab initio simulation and theoretical study of collective dynamics in liquid Sb at 973 K. An application of the GCM (generalized collective modes) theoretical approach to analysis of simulation-derived time correlation functions resulted in two types of propagating eigenmodes. We found that the almost flat dispersion of the high-frequenc...

We report an ab initio simulation study of changes in structural and dynamic properties of liquid Si at 7 pressures ranging from 10.2 GPa to 24.3 GPa along the isothermal line 1150 K, which is above the minimum of the melting line. The increase of pressure from 10.2 GPa to 16 GPa causes strong reduction in the tetrahedral ordering of the most close...

Ru‐porphyrins act as convenient pedestals for the assembly of N‐heterocyclic carbenes (NHCs) on solid surfaces. Upon deposition of a simple NHC ligand on a close packed Ru‐porphyrin monolayer, an extraordinary phenomenon can be observed: Ru‐porphyrin molecules are transferred from the silver surface to the next molecular layer. We have investigated...

The production of high‐quality hexagonal boron nitride (h‐BN) is essential for the ultimate performance of 2D materials‐based devices, since it is the key 2D encapsulation material. Here, a decisive guideline is reported for fabricating high‐quality h‐BN on transition metals. It is crucial to exclude carbon from the h‐BN related process, otherwise...

The production of high-quality hexagonal boron nitride (h-BN) is essential for the ultimate performance of two-dimensional (2D) materials-based devices, since it is the key 2D encapsulation material. Here, a decisive guideline is reported for fabricating high-quality h-BN on transition metals: It is crucial to exclude carbon from h-BN related proce...

Ru‐porphyrins act as convenient pedestals for the assembly of N‐heterocyclic carbenes (NHCs) on solid surfaces. Upon deposition of a simple NHC ligand on a close packed Ru‐porphyrin monolayer, an extraordinary phenomenon can be observed: Ru‐porphyrin molecules are transferred from the silver surface to the next molecular layer. We have investigated...

Silicene, the two-dimensional (2D) allotrope of silicon, is a promising material for electronics. So far, the most direct synthesis strategy has been to grow it epitaxially on metal surfaces; however, the effect of the strong silicon-metal interaction on the structure and electronic properties of the metal-supported silicene is generally poorly und...

The conformation of molecules on surfaces is decisive for their functionality. For the case of the endofullerene paramagnet Sc2TbN@C80 the conformation is linked to an electric and a magnetic dipole moment. Therefore a workfunction change of a substrate with adsorbed molecules, qualifies the system to be magnetoelectric. One monolayer of Sc2TbN@C80...

Gold mobilization, transfer, and concentration in the Earth’s crust are controlled by hydrothermal sulfur- and chloride-bearing fluids. Yet the exact chemical identity, structure, and stability of Au-bearing species and, in particular, the respective contributions of the sulfide (HS−) and trisulfur ion (S3⋅−) ligands to Au transport lack direct in...

Applying strong direct current (DC) electric fields on the apex of a sharp metallic tip, electrons can be radially emitted from the apex to vacuum. Subsequently, they magnify the nanoscopic information on the apex, which serves as a field emission microscope (FEM). When depositing molecules on such a tip, peculiar electron emission patterns such as...

Applying strong direct current (DC) electric fields on the apex of a sharp metallic tip, electrons can be radially emitted from the apex to vacuum. Subsequently, they magnify the nanoscopic information on the apex, which serves as a field emission microscope (FEM). When depositing molecules on such a tip, peculiar electron emission patterns such as...

We assess the crucial role of tetrapyrrole flexibility in the CO ligation to distinct Ru‐porphyrins supported on an atomistically well‐defined Ag(111) substrate. Our systematic real‐space visualisation and manipulation experiments with scanning tunnelling microscopy directly probe the ligation, while bond‐resolving atomic force microscopy and X‐ray...

The CO ligation to two different ruthenium porphyrins on the Ag(111) surface under vacuum was investigated experimentally and theoretically. The electronic and geometric changes upon ligation as well as the energetics of the process were elucidated. The surface adaptability of the porphyrin macrocycle conformation proves crucial for CO binding. Ab...

Significance Iron silicide (FeSi) provides multiple fascinating features whereby intriguing functional properties bearing significant application prospects were recognized. FeSi is understood notably as a correlated d -electron narrow-gap semiconductor and a putative Kondo insulator, hosting unconventional quasiparticles. Recently, metallic surface...

The controlled arrangement of N-heterocyclic carbenes (NHCs) on solid surfaces is a current challenge of surface functionalization. We introduce a strategy of using Ru porphyrins in order to control both the orientation and lateral arrangement of NHCs on a planar surface. The coupling of the NHC to the Ru porphyrin is a facile process which takes p...

The structure of a cyclic peptide with important biological functionalities, cyclosporin A (CsA), is investigated at the single molecule level. Its adsorption on Cu(111) under ultra-high vacuum is characterised with scanning tunnelling microscopy (STM) and density functional theory. With STM investigations, we demonstrate element specific on-surfac...

The data presented here concern the photophysical characterization of luminescent MCM-41 nanoparticles doped with 3-hydroxyflavone and 7-hydroxyflavone, two fluorescent flavonoids. UV-Vis and fluorescence spectra obtained on freshly-prepared samples and aged (2 months exposed to air) samples are shown. The effect of light exposure is also studied....

Flavones and flavonols are naturally-occurring organic molecules with interesting biological, chemical and photophysical properties. In recent years their interaction with silica surfaces has received increasing attention. In this work, the flavonol 3-hydroxyflavone (3HF) and the flavone 7-hydroxyflavone (7HF) have been encapsulated in MCM-41 mesop...

We report an {\it ab initio} simulation study of changes in structural and dynamic properties of liquid Si at 7 pressures ranging from 10.2 GPa to 24.3 GPa along the isothermal line 1150~K, which is above the minimum of the melting line. The increase of pressure from 10.2 GPa to 16 GPa causes strong reduction in the tetrahedral ordering of the most...

Ionic liquids (IL) are promising electrolytes for electrochemical applications due to their remarkable stability and high charge density. Molecular dynamics simulations are essential for a better understanding of the complex phenomena occurring at the electrode-IL interface. In this work, we have studied the interface between graphene and 1-ethyl-3...

The image visualizes three parameters used to control the electronic structure of adsorbed metal‐organic complexes, namely the nanostructured hexagonal boron nitride support, the tip of a scanning probe microscope, and the molecular environment. The templating functionality of the atomically thin hexagonal boron nitride layer is highlighted by the...

The use of molecular materials in solar cells and nano‐electronics demands a fundamental understanding and control of their electronic properties. Particularly relevant is the molecular response to the environment, that is, the interaction with the support and adjacent molecules, as well as the influence of electrostatic gating. Here, the control o...

Non-monotonous changes in velocity autocorrelations across the transformation from molecular to atomic fluid in hydrogen under pressure are studied by ab initio molecular dynamics simulations at the temperature 2500 K. We report diffusion coefficients in a wide range of densities from purely molecular fluid up to metallic atomic fluid phase. An ana...

We report the observation of a pressure-induced non-monotonic behavior of the long-wavelength asymptote of total charge density fluctuations right in the region of molecular-to-atomic fluid transformation from ab-initio molecular dynamics (AIMD) simulations of fluid hydrogen. Screening in the total charge density composed of point protons and distr...

Non-monotonous changes in velocity autocorrelations across the transformation from molecular to atomic fluid in hydrogen under pressure are studied by ab initio molecular dynamics simulations at the temperature 2500 K. We report diffusion coefficients in a wide range of densities from purely molecular fluid up to metallic atomic fluid phase. An ana...

Ionic liquids (IL) are promising electrolytes for electrochemical applications due to their remarkable stability and high charge density. Molecular dynamics simulations are essential for better understanding the complex phenomena occurring at the electrode-IL interface. In this work, we have studied the interface between graphene and 1-ethyl-3-meth...

In situ preparation of oxotitanium tetraphenylporphyrin (TiO-TPP) on Ag(111) under ultra-high vacuum conditions was achieved in a multi-step procedure starting from adsorbed free-base tetraphenylporphyrin (2H-TPP). The final product as well as the intermediate titanium tetraphenylporphyrin (Ti-TPP) were characterized by a suite of surface-sensitive...

The stability of magnetic information stored in surface adsorbed single‐molecule magnets is of critical interest for applications in nanoscale data storage or quantum computing. The present study combines X‐ray magnetic circular dichroism, density functional theory and magnetization dynamics calculations to gain deep insight into the substrate depe...

There is enormous recent interest in weak, van der Waals-type (vdW) interactions due to their fundamental relevance for two-dimensional materials and the so-called vdW heterostructures. Tackling this problem using computer simulation is very challenging due to the nontrivial, nonlocal nature of these interactions. We benchmark different treatments...

Extended organometallic honeycomb alkynyl-silver networks have been synthesized on a noble metal surface under ultrahigh vacuum conditions via a gas-mediated surface reaction protocol. Specifically, the controlled exposure to molecular oxygen efficiently deprotonates terminal alkyne moieties of 1,3,5-tris-(4-ethynylphenyl)benzene (Ext-TEB) precurso...

Endohedral fullerenes, such as Dy2ScN@C80, are single-molecule magnets with long relaxation times of their magnetization. An open and anisotropic 4f electron shell in the lanthanides (here Dy) imposes a magnetic moment that maintains its orientation at liquid-helium temperatures for macroscopic times. If these molecules shall be used as single-bit...

In article number 1804066, Hamid Oughaddou and co‐workers synthesize a single‐layer of blue phosphorene on Au(111) using molecular beam epitaxy. Scanning tunneling microscopy images show high‐quality and ordered monolayer phosphorene. Density functional theory calculations support a blue phosphorene layer presenting two different structures while p...

3-hydroxyflavone (3HF) is a widely studied molecule that acts as a simplified prototype of biological, more complex flavonoids. Its solvation mechanism is still under investigation. Here we report a joint experimental and simulation study of the vibrational properties of 3HF in gas phase and in simple liquids tetrachloromethane, chloroform and acet...

Phosphorene is a new 2D material composed of a single or few atomic layers of black phosphorus. Phosphorene has both an intrinsic tunable direct bandgap and high carrier mobility values, which make it suitable for a large variety of optical and electronic devices. However, the synthesis of single‐layer phosphorene is a major challenge. The standard...

Ions inside Fullerene molecules are model systems for the study of the electrostatic interaction across a single layer of carbon. For TbSc2N@C80 on h-BN/Ni(111) we observe with high-resolution x-ray photoelectron spectroscopy a splitting of the C 1s core level. The data may be explained quantitatively with density functional theory. The correlation...

There are currently no experimental techniques that combine atomic resolution imaging with elemental sensitivity and chemical fingerprinting on single molecules. The advent of using molecular-modified tips in non-contact atomic force microscopy (nc-AFM) has made it possible to image (planar) molecules with atomic resolution. However, the mechanisms...

There has been enormous interest in weak, van der Waals-type interactions due to their fundamental relevance in the field of two-dimensional materials and the so-called van der Waals heterostructures. Tackling this problem using computer simulation is extremely challenging due to the non-trivial, non-local nature of these interactions. We benchmark...

The adsorption of molecules on surfaces affects the surface dipole and thus changes in the work function may be expected. The effect in change of work function is particularly strong if charge between substrate and adsorbate is involved. Here we report the deposition of a strong electron acceptor molecule, tetrafluorotetracyanoquinodimethane C$_{12...

Interfacial supramolecular self-assembly represents a powerful tool for constructing regular and quasicrystalline materials. In particular, complex two-dimensional molecular tessellations, such as semi-regular Archimedean tilings with regular polygons, promise unique properties related to their nontrivial structures. However, their formation is cha...

Although on-surface metalation protocols of tetrapyrroles with 3d metals are well established, reports on the formation of lanthanide tetrapyrrole complexes are scarce. Here, we address the synthesis of lanthanide-tetrapyrrole units in detail, refining earlier findings. Specifically, the formation of cerium tetraphenylporphyrin (Ce-TPP) was induced...

Metallo-supramolecular engineering on surfaces provides a powerful strategy toward low-dimensional coordination architectures with prospects for several application fields. To date, most efforts have relied on transition metal centers, and only recently did we pioneer lanthanide-directed assembly. Coordination spheres and motifs with rare-earth ele...

Quantum ESPRESSO is an integrated suite of open-source computer codes for quantum simulations of materials using state-of-the art electronic-structure techniques, based on density-functional theory, density-functional perturbation theory, and many-body perturbation theory, within the plane-wave pseudo-potential and projector-augmented-wave approach...

By means of scanning tunnelling microscopy (STM), complementary density functional theory (DFT) and X-ray photoelectron spectroscopy (XPS) we investigate the binding and self-assembly of a saturated molecular layer of model N-heterocyclic carbene (NHC) on the Cu(111), Ag(111), and Au(111) surfaces under ultra-high vacuum (UHV) conditions. XPS revea...

Quantum ESPRESSO is an integrated suite of open-source computer codes for quantum simulations of materials using state-of-the art electronic-structure techniques, based on density-functional theory, density-functional perturbation theory, and many-body perturbation theory, within the plane-wave pseudo-potential and projector-augmented-wave approach...

Atomically thin hexagonal boron nitride (h-BN) layers on metallic supports represent a promising platform for the selective adsorption of atoms, clusters, and molecular nanostructures. Specifically, scanning tunneling microscopy (STM) studies revealed an electronic corrugation of h-BN/Cu(111), guiding the self-assembly of molecules and their energy...

Electron diffraction is a standard tool to investigate the atomic structure of surfaces, interfaces, and adsorbate systems. In particular, photoelectron diffraction is a promising candidate for real-time studies of structural dynamics combining the ultimate time resolution of optical pulses and the high scattering cross-sections for electrons. In v...

We report on the surface-guided synthesis of an unprecedented dinuclear organocobalt complex, its self-assembly into a complex nanoarchitecture, and a single-molecule level investigation of its switching behavior. Initially, an organic layer is prepared by depositing hexakis((trimethylsilyl)ethynyl)-benzene under ultra-high vacuum conditions onto A...

Extensive ab initio simulations of ice-water basal interface at seven temperatures in the range 250–400 K were performed in NVT and NPT ensembles with a collection of 389 water molecules in order to estimate the melting point of ice from direct liquid-solid two-phase coexistence. Density functional theory with the BLYP (Becke-Lee-Yang-Parr) exchang...

The chemistry of aluminium or oxo-aluminium in water is still relatively unknown, although it is the basis for many chemical and industrial processes, including floc- culation in water treatment plants. Trimeric species have a predominant role in the formation of the Keggin cations, which are the basic building block of aluminium- based chemicals....

The collective dynamics in liquid water is an active research topic experimentally, theoretically and via simula- tions. Here, ab initio molecular dynamics simulations are reported in heavy and ordinary water at temperature 323.15 K, or 50°C. The simulations in heavy water were performed both with and without dispersion correc- tions. We found that...

The effect of electronic dispersion over a wide variety of SiO2 polymorphs (faujasite, ferrierite, α-cristobalite, α-quartz, coesite, and stishovite) is investigated using state-of-the-art density functional theory. Different functionals and dispersion correction schemes are compared, ranging from the local density approximation to fully nonlocal e...

Significance Gold resources on Earth result from an exceptional concentration phenomenon yielding metal contents in ore a thousand to a million times higher than those in common rocks. We show that this process is controlled by sulfur radical ions ( S 3 − ), which strongly bind Au in aqueous solution at elevated temperatures and pressures and allow...

The cinchona alkaloids cinchonidine and cinchonine belong to the most efficient chiral modifiers for the noble metal-catalyzed enantioselective hydrogenation of C[double bond, length as m-dash]O and C[double bond, length as m-dash]C bonds. Under reaction conditions these modifiers are coadsorbed on the noble metal surface with hydrogen. Using densi...

Unlike phonons in crystals, the collective excitations in liquids cannot be treated as propagation of harmonic displacements of atoms around stable local energy minima. The viscoelasticity of liquids, reflected in transition from the adiabatic to elastic high-frequency speed of sound and in absence of the long-wavelength transverse excitations, res...

The interplay between the electronic structure and reconstruction of the geometry on a surface is an intriguing and exciting investigation. One classic example that has been one of the first systems to be identified using the angularly resolved photo-emission spectroscopy and scanning tunnelling microscopy is the Herringbone reconstruction on the A...

The proton disorder in ice has a key role in several properties such as the growth mode, thermodynamical properties, and ferroelectricity. While structural phase transitions from proton disordered to proton ordered ices have been extensively studied, much less is known about their electronic and optical properties. Here, we present ab initio many b...