Transborder QuantumChemPhys Lab Meeting

Baiona, 5th – 6th November 2018

LIST OF PARTICIPANTS ISM (Bordeaux)

1. Méreau, Raphael 2. Crespos, Cédric 3. Bonnet, Laurent 4. Castet, Frédéric 5. Desmedt, Arnaud 6. Ibargüen Becerra, César 7. Larregaray, Pascal 8. Tonnelé, Claire 9. Lescos, Laurie

LOMA(Bordeaux)

10. Avriller, Rémi CFM - DIPC (Donostia)

11. Sánchez Portal, Daniel 12. Arnau, Andrés 13. Díez Muiño, Ricardo 14. Juaristi, Iñaki 15. Mansouri, Masoud 16. García Fernández, Carlos 17. Rivero Santamaría, Alejandro

UPV/EHU - DIPC (Donostia)

18. Casanova, David 19. Matito, Eduard 20. Mitxelena, Ion 21. Sandoval-Salinas, Maru 22. Jiménez-Izal, Elisa 23. Via-Nadal, Mireia 24. Sitkiewicz, Sebastian 25. Postils, Verònica 26. Carreras, Abel 27. Xu, Xiang 28. Casademont-Reig, Irene

JOINT PhD

29. Rodríguez Fernández, Alberto 30. Baumard, Julie 31. Schaeverbeke, Quentin 32. Uranga, Olatz 33. Peña-Torres, Alejandro 34. Espert, Sophie 35. Bojnowski, Bogusz

PROGRAM Monday 5th November

o 09.45h: Welcome Coffee at "Hotel Le Bayonne" 10.20h-10.30h: Opening: The QuantumChemPhys Lab 10.30h-12.30h: Scientific Session ‘Joint PhD Projects’

10.30h-10.50h: Electronic Transport through a Quantum Dot Strongly Coupled to an Electromagnetic Cavity, Quentin Schaerverbeke 10.50h-11.10h: Generation of a superconducting vortex via Néel skyrmions, Julie Baumard 11.10h-11.30h: Sample edge polarization in 1D systems with spin orbit coupling, Bogusz Bujnowski 11.30h-11.50h: Optical Properties of Quadrupolar and Bi-Quadrupolar Dyes: Intra and Inter Chromophoric–Interactions, Olatz Uranga 11.50h-12.10h: Impact of van der Waals interactions in adsorption and recombination processes of N2 on W(100), Alejandro Peña Torres 12.10h-12.30h: When Classical Trajectories Get to Quantum Accuracy: the Scattering of H2 on Pd(111), Alberto Rodríguez-Fernández

o 12.30h-14.30h: Lunch at Hotel Le Bayonne

14.30h-16.10h: Scientific Session ‘Light and Electrons’

14.30h-14.50h: Nonlinear Optical Response of Photoswitchable Self-Assembled Monolayers, Claire Tonnelé 14.50h-15.10h: Intramolecular Singlet Fission in Homo-Conjugated Dimers, María Eugenia Sandoval-Salinas 15.10h-15.30h: Assessment of Spin-resolved G0W0 Calculations, implemented by PySCF-NAO, Masoud Mansouri 15.30h-15.50h: Charge-transfer chemical reactions for molecular populations confined inside a nanofluidic Fabry-Perot cavity, Remi Avriller 15.50h-16.10h: Insights into nanoplasmonics from first-principles time-dependent density functional simulations, Daniel Sánchez-Portal

o 16.10h-16.40h: Coffee Break

16.40h-19.00h: Scientific Session ’Surfaces and Nanostructures’

16.40h-17.00h: Atomic Scattering of H and N on W(100): Insights into the trapping mechanisms, César Ibargüen-Becerra 17.00h-17.20h: Nanoalloying MgO-Deposited Pt Clusters with Si for Controlling the Selectivity of Alkane Dehydrogenation, Elisa Jimenez-Izal

17.20h-17.40h: Molecular transition metal electrides – Are they possible?, Sebastian P. Sitkiewicz 17.40h-18.00h: Spin Control Induced by Molecular Charging in a Transport Junction, Carlos García Fernández 18.00h-18.20h: Ab Initio Molecular Dynamics Study of alignment resolved O2 scattering from highly oriented pyrolytic graphite, Alejandro Rivero Santamaria 18.20h-18.40h: New electrolytes for fuel cells based on super-protonic conducting hydrates, Arnaud Desmedt 18.40h-19.00h: Evidence of large spin-orbit coupling effects in quasi-free-standing graphene on Pb/Ir(111), Andrés Arnau

19.00h-20.00h: Meeting of the Scientific Committee

o 21h00: Dinner at Restaurant Rotisserie du Roy Leon Tuesday 6th November 9.45h-11.45h: Scientific Session ’Advances in Methodology’

9.45h-10.05h: Oxidation States from Wave Function Analyses: the EOS formalism, Verònica Postils 10.05h-10.25h: A Novel Signature of Dispersion Interactions: Intracule functions, Mireia Via-Nadal 10.25h-10.45h: Natural Orbital Functional Theory, Ion Mitxelena 10.45h-11.05h: New tool to describe the aromaticity in large systems, Irene Casademont-Reig 11.05h-11.25h: Extracting the phonon anharmonic properties from molecular dynamics simulations using DynaPhoPy code, Abel Carreras 11.25h-11.45h: Quantum molecular predictions from classical paths, Laurent Bonnet

11.45h-11.50h: Closing Remarks

o 12.30h: Lunch at Restaurant Le Chaho Additional information:

- Time slots allocated for the talks are 15 minutes + questions. Please stick to your time. - The goal is to provide a brief description or highlights of recent scientific work.

Research performed in the general framework of the QuantumChemPhys Lab is preferred.

- Tuesday afternoon is left for informal scientific discussions among researchers.

BOOK OF ABSTRACTS

Electronic Transport through a Quantum Dot Strongly Coupled to an Electromagnetic Cavity Quentin Schaerverbeke Cavity QED has been a tremendous way to study the interaction between light and matter through phenomenons such as the Rabi splitting. In recent years, technological progress has allowed to study a new variety of systems in which the photons of a cavity are coupled to nanocircuits. In this new frame called Mesoscopic QED it is now relevant to study the effect of the transport of electrons on the light of the cavity and vice versa. Moreover measurement of the electronic current could become a useful and complementary spectroscopy of the cavity. Here we propose a way to describe electronic transport coupled to photons. We describe the interaction between photons and electrons, electronic transport through a nano circuit but also the damping of the cavity which is mandatory for describing cavity with a bad quality factor such as plasmonic nano cavities. We also describe the effect of an external source of light. For all those interactions we show a way to compute the current. As a first approach and in order to isolate the specificities that comes with electronic transport, we show the current for a single level quantum dot which exhibit similarities with the Franck-Condon blockade regime. [1] R. Chikkaraddy, J. J. Baumberg , B. de Nijs, Nature (2016) [2] J. Koch, F. von Oppen, A. V. Andreev, Phy. Rev. B (2006) [3] H. Imada, K. Miwa, Y. Kim, PRL (2017) [4] R. H. Dicke, Phys. Rev. (1954) [5] R. Leturcq, F. von Oppen K. Ensslin, Nature Physics (2009) [6] S. Braig, K. Flensberg, Phys. Rev. B (2003) [7] L. Childress, A. S. Sørensen, and M. D. Lukin, Phys. Rev. A (2004)

Generation of a superconducting vortex via Néel skyrmions Julie Baumard We consider a type-II superconducting thin film in contact with a Néel skyrmion. The skyrmion induces spontaneous currents in the superconducting layer, which under the right condition generate a superconducting vortex in the absence of an external magnetic field. We compute the magnetic field and current distributions in the superconducting layer in the presence of Néel skyrmion.

Sample edge polarization in 1D systems with spin orbit coupling Bogusz Bujnowski Starting from a work on a diffusive Josephson junction involving SOC materials I ran into discrepancies between numerical simulations and previously obtained analytical expressions for the Josephson current. This “problem” actually was due to an interesting effect. In systems with SOC and exchange fields equilibrium spin currents can flow and lead to spin accumulation at the edges.

Optical Properties of Quadrupolar and Bi-Quadrupolar Dyes: Intra and Inter Chromophoric–Interactions Olatz Uranga In this talk I will present the main results derived from my joint PhD studies between the University of Bordeaux, the University of the Basque Country and the Donostia International Physics Center. More concretely, I will show the theoretical investigation carried out for three boron-difluoride-curcuminoid derivatives and their covalent homodimers chemically linked through a polymethylenic chain. Low-lying electronic excited states and photophysical properties of the monomeric species will be described as the convolution of different donor-acceptor intramolecular excitations. In the case of the folded forms of the covalent dimers, the strong electronic coupling results in low-lying excitations with sizable mixings of intra- and inter- chromophoric contributions, which cannot be described by means of the Kasha model of interacting chromophores. I will demonstrate how decomposition of the computed excitations in terms of diabatic states can be extremely valuable in order to identify and quantify the nature of electronic transitions in the presence of several electron donor and acceptor fragments.

Impact of van der Waals interactions in adsorption and recombination processes of N2 on W(100) Alejandro Pena Torres Adsorption and Eley-Rideal (ER) recombination dynamics of N2 on a W(100) surface are investigated via quasi-classical trajectories calculations making use of a DFT-based potential energy surface (PES) constructed using a functional that accounts for non-local interactions. Non-adiabatic effects are included in the calculations simulating energy exchange with the lattice phonons and electrons. Due to the long range interactions, the resulting PES exhibits a significant decrease of the potential energy barriers that the molecule (atom) faces when approaching the surface as compared with previous theoretical results. This feature affects greatly the dynamics, particularly in the low-energy regime. A qualitative agreement with experiments is obtained for the adsorption process when energy dissipation effects are included. Likewise, a significant increase compared with previous works in the cross section for ER recombination at low energies is obtained.

When Classical Trajectories Get to Quantum Accuracy: the Scattering of H2 on Pd(111) RODRIGUEZ-FERNANDEZ Alberto;A,B,C BONNET Laurent;A CRESPOS Cedric;A LARREGARAY Pascal;A DIEZ-MUINO RicardoB,C A) ISM,UMR5255, U. Bordeaux/CNRS, F-33400, Talence; B) Centro de Física de Materiales CFM/MPC(CSIC-UPV/EHU),PaseoManueldeLardizabal5,20018Donostia-SanSebastiań,Spain; C) Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal4,20018 Donostia-SanSebastiań,Spain Contact: alberto.rodriguez-fernandez@u-bordeaux.fr When elementary reactive processes occur at so low energies that only a few states of reactant and/or product are available, quantum effects usually strongly manifest and the description of the dynamics within the classical framework fails. If quantum dynamics calculations are achievable when the number of degrees of freedom remains small (typically < 10), quasi-classical trajectories (QCT) are the only practical tool to treat bigger systems. We here show how introducing semi-classical corrections into the classical formalism improves the QCT method in the quantum regime. In particular, we focus on the Gaussian Binning (GB)1 and the Adiabatic Correction (AC)2 to account for internal motion quantization and classical overweighting of adiabatic non-reactive collisions in the study of H2 scattering on Pd (111), which has been intensively studied previously3. The application of these corrections leads to an unprecedented and spectacular quantitative agreement with state-of-the-art quantum dynamics calculations.

Figure 1. Sticking probability for H2 (0,0) on Pd(111) as a function of collision energy.

KEYWORDS: Semiclassical methods, gaussian binning (GB), molecular scattering, surface interaction.

1 L.Bonnet, J.C.Rayez. Chemical Physics Letters 277 (1997) 183-190

2 C. Crespos, J. Decock, P. Larrégaray, and L. Bonnet. J. Phys. Chem. C, 2017, 121 (31), pp 16854–16863

3 H.F. Busnengo, E. Pijper, M.F. Somers, G.J. Kroes, A. Salin, R.A. Olsen, D. Lemoine , W. Dong. Chemical Physics

Letters 356 (2002) 515–522

Nonlinear Optical Response of Photoswitchable Self-Assembled Monolayers Claire Tonnelé1, Kornelia Pielak1,2, Jean Deviers1, Luca Muccioli3, Benoît Champagne2, Frédéric Castet1 1 Institut des Sciences Moléculaires (ISM, UMR CNRS 5255), Université de Bordeaux, 351 Cours de la Libération, 33405 Talence, France 2 Unité de Chimie Physique Théorique et Structurale, Département de Chimie, Namur Institute of Structured Matter, Université de Namur, Belgique 3 Department of Industrial Chemistry "Toso Montanari", Université de Bologne, Viale Risorgimento 4, 40136 Bologne, Italie. email: claire.tonnele@u-bordeaux.fr Organic molecules possessing two optically switchable states with large contrasts in their linear and non linear optical (NLO) responses are particularly appealing for designing nanoscale memory devices with non-destructive readout capacity (Figure 1). Exploiting the NLO response in fact enables the reading of the stored information outside the UV/visible absorption band, so that unwanted erasure during reading can be avoided. In this context, the rational design of self-assembled monolayers (SAMs) constitutes a very versatile approach for surface engineering and controlled integration of such systems in devices.

Figure 1: a) Schematic representation of information storage with visible light and reading with infrared light in NLO-based memory devices b) Selected molecular switches and their photoconversion : azobenzene (AZO), benzazolo-oxazolidine (BOX)

Controlling the supramolecular organization being a key element in the modulation of the NLO response of the layer, a combined MD/QM approach has been used to describe the detailed morphology of BOX- and AZO-based systems, and evaluate their NLO response. These simulations revealed that the disorder within the SAM is not detrimental to the NLO contrast but also shed light on some structure-NLO response correlations, opening the way for a rational optimization of these systems.

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Intramolecular Singlet Fission in Homo-Conjugated Dimers

María Eugenia Sandoval-Salinasa,b, David Casanovab aDepartament de Ciència de Materials i Química Física, Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, Martí i Franquès 1-11, Barcelona 08028, Spain bIKERBASQUE - Basque Foundation for Science (DC) & Donostia, International Physics Center & Kimika Fakultatea Euskal Herriko Unibertsitatea, Paseo Manuel de Lardizabal, 4, 20018 Donostia-San Sebastián, Euskadi, Spain Email: msandosa9@alumnes.ub.edu

Singlet fission (SF) is a photophysical process where a spin singlet excited state splits into two spin-triplet states through an intermediate multiexcitonic state that corresponds to a correlated triplet-pair state[1],[3].

𝑆! ⇌ 𝑇𝑇! ⇌ 𝑇! + 𝑇! Homo-conjugated systems are organic molecules in which two or more π-moieties are separated by a non-conjugating group[2]. Homo-conjugation results in a unique arrangement of conjugated fragments providing a novel way to chemically connect chromophoric units and control their electronic interaction. These properties might be of great use in singlet fission (SF), since optimal electronic coupling is a key ingredient for the efficient generation of two independent triplets from a singlet exciton[1]. In this work, we employ different computational chemistry tools within the framework of Density Functional Theory and Wave Function Theory to identify the nature of the low-lying electronic states, characterize the particularities of electronic coupling in homo-conjugated systems, describe the intrachromophoric coupling and predict the overall viability of intramolecular SF in these type of covalent dimers. References.

[1] Chem. Rev. 2010, 110 (11), 6891-6936 [2] Pure & App. Chem. 1994, 66 (5), 1077–1184 [3] Chem. Rev. 2018, 118 (15), 7164-7207

Assessment of Spin-resolved G0W0 Calculations, implemented by PySCF-NAO Masoud Mansouri Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 5 and Centro de Fısica de Materiales, Centro Mixto CSIC-UPV/EHU 20018 Donostia-San Sebastian, Spain Email: ma.mansouri@dipc.org Computational spectroscopy is enhancing into a crucial comple- mentary approach to empirical spectroscopy. It is not only able to fa- cilitate the interpretation of experimental spectra but also can predict properties of novel and unexplored materials. To validate computa- tional approaches, theoretical benchmarks are essential. For solids, GW approximation has become the method of choice for the cal- culation of quasi-particle spectra as measured in direct and inverse photoemission. In most applications, GW is applied as a one-shot correction (G0W0) to the electronic spectrum of a mean-field start- ing Hamiltonian. In this study, a thorough assessment of G0W0, with a Hartree-Fock (HF) starting point for gas-phase molecules using PySCF-NAO code is provided. PySCF includes implementations of HF for restricted, unrestricted, closed- and open-shell Slater determi- nant references[1–4]. Keywords: G0W0 approximation, Numerical atomic Orbital, Ionization potential. References [1] P. Koval, M. Barbry, and D. Sanchez-Portal. PySCF-NAO: an efficient and flexible implementation of linear response time dependent density functional theory with numerical atomic orbitals. Comput. Phys. Commun., 2018. [2] P. Koval, M. Mu ̈ller, D. S ́anchez-Portal, et al. Hedin’s GW calculations with numerical atomic orbitals (NAO). In preparetion, 2018. [3] Qiming Sun, Timothy C Berkelbach, et al. Pyscf: the python-based simulations of chemistry framework. Comput. Mol. Sci., 8(1):e1340, 2018. [4] Michiel J van Setten, Fabio Caruso, Sahar Sharifzadeh, Xinguo Ren, Matthias Scheffler, et al. GW100: Benchmarking G0W0 for molecular systems, Supplementary material. J. Chem. Theory Comput., 2015.

ATOMIC SCATTERING OF H AND N ON W(100):INSIGHTS INTO THE TRAPPING MECHANISMS IBARGÜEN-BECERRA CésarA; CRESPOS Cedric;A LARREGARAY PascalA,B A) Université Bordeaux, THEO-ISM, UMR5255, F-33400 Talence, France B) CNRS, ISM, UMR5255, F-33400 Talence, France cesar.ibarguen-becerra@u-bordeaux.fr The atomic scattering of H and N on W(100) is studied by means of Quasi-Classical Trajectories simulations (QCT). Two different density functional theory-based potential have been used. We explored a large range of initial collision energy between 10-1000 meV. Normal and off normal initial angle of incidence are considered. QCT simulations have been carried out under the Born-Oppenheimer Static Surface (BOSS). The dissipation energy effect into the surface via phonons or electron hole (e-h) pairs has been taken into account by using the Generalized Langiven Oscillator (GLO) and the Local Density Friction Approximation model, respectively. Preferred sites for adsorption and absorption are identified. Mean energy released to the surface is also analyzed. The We propose several scenarios for trapping mechanism. Our results suggest that for N atomic scattering the trapping is governed by dissipation via phonons mainly, while electron-hole (e-h) pair excitation rules the H scattering.

Figure 1.

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of collision energy

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incidence. Results for H/W(100) to the left and for N/W(100) are shown.

Keywords: Scattering, dissipation, e-h pairs excitation, surface, adsorption, absorption

Insights into nanoplasmonics from first-principles time-dependent density functional simulations Daniel Sánchez-Portal Centro de Física de Materiales CSIC-UPV/EHU and DIPC, San Sebastián, Spain Email: daniel.sanchez@ehu.eus Our optimal implementation of time-dependent density functional theory within linear response allows computing the optical properties of systems with several thousands of atoms [1,2]. We applied this method to study the dependence of the near-field enhancement and localization on the structural details of the plasmonic nano-gaps [3,4], the different size dispersion of the plasmon resonance of silver and sodium nanoparticles and how this behaviour correlates with the presence of 4d electrons in the Ag case [2], and more recently to describe valence EELS [5].

In this talk I will concentrate mostly in the correlation between transport properties across sub-nanometric metallic gaps and the optical response of the system. In Ref. [6] we presented a study of the simultaneous evolution of the structure and the optical response of a plasmonic junction as the particles forming the cavity approach and retract. Atomic reorganizations are responsible for a large hysteresis of the plasmonic response of the system, which shows a jump-to-contact instability during the approach process and the formation of an atom-sized neck across the junction during retraction. Our calculations show that, due to the conductance quantization in metal nanocontacts, small reconfigurations play a crucial role in determining the optical response. We observe abrupt changes in the intensity and spectral position of the plasmon resonances, and find a one-to-one correspondence between these jumps and those of the quantized transport as the neck cross-section diminishes. These results point out to a connection between transport and optics at the atomic scale at the frontier of current optoelectronics.

The author acknowledges financial support from FP7 FET-ICT project No. 610446 project, MINECO (Grant No. MAT2013-46593-C6-2-P), the Basque Dep. de Educación and the UPV/EHU (Grant No. IT-756-13).

[1] P. Koval, et al., J. Phys.: Cond. Matter 28, (2016) 214001 [2] M. Barbry, N. E. Koval, J. Aizpurua, D. Sánchez-Portal and P. Koval, submitted [3] M. Barbry, et al., Nano Letters 354, (2015) 216 [4] M. Urbieta, et al., ACS Nano 12, (2018) 585-595 [5] M. Barbry, P. Koval and D. Sánchez-Portal, in preparation (2018) [6] F. Marchesin, et al., ACS Photonics 3, (2016) 269-277

Figure 1: There is a one-to-one correspondence between the jumps in the current flowing

through the metal neck, its cross-section and the far-field optical response at the frequency

of the so-called charge transfer plasmon (CTP).

Nanoalloying MgO-Deposited Pt Clusters with Si for Controlling the Selectivity of Alkane Dehydrogenation Elisa Jimenez-Izal1 , Huanchen Zhai2, and Anastassia N. Alexandrova2 ,3 1Kimika fakultatea, Euskal Herriko Unibertsitatea (UPV/EHU), and Donostia International Physics Center (DIPC), P. K. 1072, 20080 Donostia, Euskadi, Spain 2Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California, 90095-1569. 3California NanoSystems Institute, 570 Westwood Plaza, Building 114, Los Angeles, CA 90095. With increasing environmental concerns worldwide as well as the scarcity and cost of noble metals, the use of nanocatalysts is a novel way to exploit resources more efficiently and minimize waste. The properties of metallic nanoclusters are highly sensitive to the size, shape, support and catalytic conditions. The addition or removal of just one atom, for instance, can change the selectivity, activity or stability of the catalyst [1]. This creates a complex picture but, at the same time, offers the possibility of achieving the greatest performance of the catalyst, and stability against deactivation. We aim to design catalysts with optimized properties (catalytic activity, selectivity and durability) through the understanding and manipulating the electronic structure of such catalysts. Particularly, in this work we propose silicon as coalloying agent to improve the selectivity and stability of Pt catalysts for the dehydrogenation of light alkanes [2]. Si was revealed as a promising dopant for Pt across two cluster sizes, as it appears to favor stopping dehydrogenation of alkanes at alkenes. The discovered properties of Si potentially exceed those of B, the recently proposed doping agent for Pt clusters whose effect on selectivity was confirmed experimentally [3, 4]. References: 1. Elisa Jimenez-Izal, Anastassia N. Alexandrova Annual Rev. Phys. Chem. 69, 377 (2018). 2. Elisa Jimenez-Izal, Huanchen Zhai, Jiyuan Liu, Anastassia N. Alexandrova ACS Catal. 8, 8346 (2018). 3. Jonny Dadras, Elisa Jimenez-Izal, Anastassia N. Alexandrova ACS Catal. 5, 5719 (2015). 4. Mai-Anh Ha, Eric T. Baxter, Ashley C. Cass, Scott L. Anderson, A. N. Alexandrova J. Am. Chem. Soc. 139, 11568 (2017).

Molecular transition metal electrides – Are they possible? Sebastian P. Sitkiewicz,a,b,cJosep M. Luis,c Eduard Matitoa,d

aDonostia International Physics Center (DIPC), 20018, Donostia-San Sebastian, Euskadi, Spain bKimika Fakultatea, Univ. Pais Vasco (UPV/EHU), 20018, Donostia-San Sebastian, Euskadi, Spain cInstitut de Química Computacional i Catàlisi (IQCC), Univ. Girona, 17003, Girona, Catalonia, Spain dIKERBASQUE, Basque Foundation for Science, Bilbao, Euskadi, Spain e-mail: sebastian.p.sitkiewicz@gmail.com Molecular electrides[1] are definitely very peculiar and intriguing chemical systems. In their stable ionic structures, the counterpart to the positively charged (molecular) fragments is the smallest anion possible – an isolated electron.[1] Unassigned to any nucleus, these confined electrons greatly enhance both (non)linear optical and electrical properties of the electrides. From the topological perspective these confined electrons belong to the basin of a nonnuclear attractor (NNA) (i.e. a quasiatom[2]) – a local maximum in the electronic density without the presence of nucleus.[3] The occurrence of NNAs is rare and still controversial phenomena, and thus theoretical studies on their origins were done for the simple structures built from the main groups elements, such as homo and hetero diatomics.[4,5]

In this work, we do a step further by unearthing the existence of the NNAs in small transition metal (TM) systems. Our study was inspired by the 3D geometric structure of the first TM solid state electride - yttrium carbide (Y2C), characterized with the 2D layered structure and a formal chemical formula of [Y2C]1.8+·1.8e (see Figure 1).[6] We have identified Y3 with an equilateral triangle geometry as the simplest moiety of yttrium that could give rise to the NNAs and electride-like properties, unlike in alkali metals for which the conditions for NNA occurence are much simpler (NNAs show in isolated alkali atom adducts of organic molecules[1] and simple diatomics[4,5]). By analyzing the electronic structure several low-lying excited states with different charge and spin multiplicities, we have established the connection between the existence of NNAs and unique electronic structure of the resolved yttrium systems. Moreover we performed a thorough assessment of the performance of quantum chemical methods in the predictions of such phenomenon. We believe that our findings will open the door to designing molecular electrides incorporating transition metal atoms.

[1] V. Postils et al. Chem. Comm. 2015, 51, 4865-4868 [2] M. J. Stott, E. Zaremba Phys. Rev. B 1980, 22, 1564 [3] R. F. W. Bader Atoms in Molecules. A Quantum Theory. Oxford University Press, New York, 1990 [4] L. Terrabuio et al. J. Phys. Chem. A 2016, 120, 1168-1174 [5] A. M. Pendás et al. Phys. Rev. Lett. 1999, 83,, 1930 [6] X. Zhang et al. Chem. Mater. 2014, 26, 6638-6643

Spin Control Induced by Molecular Charging in a Transport Junction. Carlos Garcia Fernandez The ability of molecules to maintain magnetic multistability in nanoscale-junctions will determine their role in downsizing spintronic devices. While spin-injection from ferromagnetic leads gives rise to magnetoresistance in metallic nanocontacts, nonmagnetic leads probing the magnetic states of the junction itself have been considered as an alternative. Extending this experimental approach to molecular junctions, which are sensitive to chemical parameters, we demonstrate that the electron affinity of a molecule decisively influences its spin transport. We use a scanning tunneling microscope to trap a meso-substituted iron porphyrin, putting the iron center in an environment that provides control of its charge and spin states. A large electron affinity of peripheral ligands is shown to enable switching of the molecular S = 1 ground state found at low electron density to S = 1/2 at high density, while lower affinity keeps the molecule inactive to spin-state transition. These results pave the way for spin control using chemical design and electrical means.

Ab Initio Molecular Dynamics Study of alignment resolved O2 scattering from highly oriented

pyrolytic graphite

A. Rivero Santamaría1*, M. Alducin 1,2, R. Díez Muiño 1,2 and J. I. Juaristi1,2,3

1 Donostia International Physics Center DIPC, San Sebastián, Spain2 Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), San Sebastián, Spain

3 Departamento de Física de Materiales, Facultad de Químicas (UPV/EHU), San Sebastián, Spain*email presenting author: arivero@dipc.org

The interaction of molecular oxygen with surfaces has been intensively studied in the last twenty years. The

tremendous advances in experimental setups have allowed to know how the stereochemistry and spin state of O 2

molecules influence the interaction dynamics and reactivity on different surfaces1. In order to contribute to the

theoretical understanding of the alignment resolved O2 scattering from highly oriented pyrolytic graphite (HOPG), we

have performed ab initio molecular dynamics (AIMD) calculations. The Vienna Ab Initio Simulation Package (VASP)3,4

was used to carry out spin polarized calculations using the generalized gradient approximation (GGA) by

Perdew−Burke−Ernzerhof (PBE)5. The ionic cores were described with the projector augmented wave (PAW) method.

The DFTD3 (BJ)6,7 correction was chosen to correct the inadequacy of the PBE functional to describe vdW interactions.

The graphite (0001) surface was described by a three layer 3 x 3 supercell separated by 16 Å from its periodic image.

The first top two layers were thermalized and allowed to move during the calculations.

The results obtained from simulations of a molecular oxygen beam with a selected orientation impinging on a

thermalized graphite surface at 110 and 300 K, with an incident energy of 200 meV, show that the long range forces

dominate the O2-HOPG interaction. The O2 collision with the surface occurs, in average, at around 3 Å from the top

graphite layer. The AIMD scattering ”total probabilities” are almost independent of the initial orientation of the

molecule and surface temperature, when only ”in plane” scattered molecules are taking into account, the differences

in the probabilities between molecules with parallel and normal orientation is enhanced. The energy loss in the

collision depends of the initial orientation of the O2 molecule, the internal energy of incident perpendicular molecules

is six times greater than parallel ones, pointing out that for end-on collisions the transfer of energy to the internal

modes is more important than the transfer of energy to the surface.

References

1. Kurahashi, M. “Oxygen adsorption on surfaces studied by a spin and alignment-controlled O2 beam”, Prog. Surf. Sci., Vol. 91, No. 1, 29-55, 2016

2. Kresse, G.; Furthmuller, J. “Efficient iterative schemes for ab initio total-energy calculations using plane wave basis set.” , Phys. Rev. B:

Condens. Matter Mater. Phys., Vol. 54, 11169−11186, 1996

3. Kresse, G.; Furthmuller, J. “Efficiency of ab initio total energy calculations for metals and semiconductors using plane wave basis set”, Comput.

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NEW ELECTROLYTES FOR FUEL CELLS BASED ON SUPER-PROTONIC CONDUCTING HYDRATES. S. Desplanche(a), F. Mauvy(b), P. Judeinstein(c), B. Kaufman(d), L. Bourgeois(a), S. Espert(a,e), D. Sanchez-Portal(e), A. Desmedt(a) (a) GSM-ISM, CNRS Univ. Bordeaux, Talence, France (b) ICMCB, CNRS Univ. Bordeaux, Pessac, France (c) LLB, CEA Saclay, 91191 Gif-sur-Yvette CEDEX, France (d)IECB, CNRS Univ. Bordeaux, Pessac, France (e)DIPC, San Sebastian, Spain The development of new devices dedicated to energy storage and production is at the center of nowadays concerns. Among the various opportunities, the fuel cell using hydrogen as an energy carrier has a high-energy efficiency. It produces no greenhouse gases and appears today as a clean and efficient solution. The fuel cell constitutes one alternative to hydrocarbons (fossil fuels) and overcomes intermittency of some renewable resources. The various fuel cells are distinguishable by the nature of the electrolyte that composes their proton exchange membrane. Materials mainly constituted of water molecules represent a new opportunity. Indeed, new solid electrolyte may be composed of Strong Acid Clathrate Hydrates. Strong acids form ionic clathrate hydrate sin which anion guest molecules are included into a cationic host cage structure [1-3]. This confinement leads to generate proton excess delocalized along water molecules of the cage network, at the origin of their high protonic conductivity [4,5]. The structure formed is largely dependent on the chemical nature of the cations but also on the hydration number. In addition to the inherent fundamental interest of the proton transport mechanism met in these acidic clathrate hydrates, the aim of the present work is to develop and study this ice-like system formed with hexafluorophosphoric acid. This system possesses a melting point closed to room temperature. Moreover, it may be referred as a super-protonic conductor. They exhibit high proton conductivity at specific conditions (hydration number, temperature) [5] that proves to be higher than that of current fuel cell membranes such as Nafion. In order to study the structure and (thermo-)dynamics of these systems, micro-Raman spectroscopy is the unique technique. Such a vibrational spectroscopic technique is indeed a powerful tool for probing selectively and spatially chemical species. The HPF6 guest molecules is known to form two clathrate phases: a high temperature phase constituted of the so-called type VII clathrate structure and a low temperature phase corresponding to the so-called type I clathrate structure [3,6]. The structural changes are observed in situ by varying the temperature, allowing the correlation of the hydration number of the strong acid with the formed structure and its thermal history. In addition, the use of a Raman spectrometer coupled to a confocal microscope offers the opportunity of observing local structures at a micrometric scale. Thanks to this capability, a new layer appearing at the boundary regions of the clathrate hydrate aggregates has been evidenced at the structural transition [7]. This layer also exhibits a time evolution, playing a key role in the structural evolution of the sample and its electrochemical properties. Finally, by combining Raman spectroscopy with conductivity measurements, NMR and DRX, the impact of this microstructuration onto the super-protonic conduction mechanism has been unraveled for the first time [8]. These original results will be presented in the perspectives of applications and fundamentals. Finally, these new electrolytes based on strong acid hydrates open questions regarding the driven factors at the origin of the observed super-protonic conduction. Theses factors are lying at a molecular and ionic level (e.g. adsorption sites and Brownian dynamics of the various ionic species), for which a fundamental understanding is required by combining experimental and theoretical strategies. In this perspective, a new Transborder Lab “Quantum Chem Phys” PhD project has started and the key issues of this project will be presented during this workshop. References [1] E.D. Sloan and C.A. Koh, Clathrate Hydrates of Natural Gases, 2008; Taylor & Francis-CRC Press: Boca Raton, FL. / [2] A. Desmedt et al, Eur. Phys. J. Special Topics 2012; 213: 103-127. / [3] D. Mootz et al, J. Am. Chem. Soc. 1987; 109: 1200-1202./ [4] L. Bedouret et al, J. Phys. Chem. B 2014; 118: 13357-13364./ [5] J. Cha et al, J. Phys. Chem. C 2008; 112: 13332-13335. [6] V. Hans Bode et al, Acta Cryst. 1955; 8: 611-614./ [7] S. Desplanche et al, 2018 in preparation. / [8] S. Desplanche et al, 2018 in preparation.

Evidence of large spin-orbit coupling effects in quasi-free-standing graphene on Pb/Ir(111) M. M. Otrokov(1,2), I. I. Klimovskikh(3), F. Calleja(4), A. M. Shikin(3), O. Vilkov(3), A. G. Rybkin(3), D. Estyunin(3), S. Muff(5,6), J. H. Dil(5,6), A. L. Vázquez de Parga(4,7), R. Miranda(4,7), H. Ochoa(8), F. Guinea(4,9), J. I. Cerdá(10), E. V. Chulkov(1,11,12), and A. Arnau(1,11,12) (1)Centro de Física de Materiales (CFM-MPC), Centro Mixto CSIC-UPV/EHU, 20018 Donostia-San Sebastián, Spain (2)Tomsk State University, 634050 Tomsk, Russia (3)Saint Petersburg State University, 198504 Saint Petersburg, Russia (4)Instituto Madrileño de Estudios Avanzados en Nanociencia, Cantoblanco 28049, Madrid, Spain (5)Institute of Physics, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland (6)Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland (7)Departamento de Física de la Materia Condensada and IFIMAC, Universidad Autónoma de Madrid, Cantoblanco 28049, Madrid, Spain (8)Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA (9)Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK (10)Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, Cantoblanco 28049, Madrid, Spain (11)Donostia International Physics Center (DIPC), 20018 Donostia-San Sebastián, Spain (12)Departamento de Física de Materiales UPV/EHU, 20080 Donostia-San Sebastián, Spain A combined scanning tunneling microscopy, angle- and spin-resolved photoemission spectroscopy and density functional theory study of graphene on Ir(111) intercalated with a well-ordered, full Pb monolayer is presented. Lead intercalation between graphene and Ir(111) reduces the coupling to the metallic substrate in such a way that its corrugation becomes negligible and distortions of the linear dispersion largely disappear, while graphene's sublattice symmetry is maintained and it turns out to be n-doped. Remarkably, the spin-orbit splittings induced by the proximity of the Ir(111) surface are preserved after Pb intercalation in a wide energy range. We further show that the Pb interlayer induces a complex spin texture with both in-plane and out-of-plane components. Our calculations reveal the origin of the out-of-plane spin components in graphene to trace back to the out-of-plane spin-polarized surface and resonance states of Ir(111), while the Pb interlayer on its own does not induce any vertical spin polarization in the carbon sheet. However, the Brillouin zone folding imposed by the rectangular symmetry of the intercalated Pb layer plays an instrumental role in the spin-orbit coupling (SOC) transfer to graphene, as well as in the linearization of its bands. Finally, since no sizeable gap is observed at the Dirac point, we suggest that an intrinsic (Kane and Mele type) SOC does not exceed the extrinsic (Rashba) SOC for graphene on Pb/Ir(111).

Oxidation States from Wave Function Analyses: the EOS formalism

Verònica Postils,a,b Eloy Ramos-Córdoba,c and Pedro Salvadorb a

Departamento de Ciencia y Tecnología de Polímeros, Euskal Herriko Unibertsitatea. 20018, Donostia-San Sebastián. Spain b

Institut de Química Computacional i Catàlisi and Departament de Química, Universitat de Girona. 17003, Girona. Spain cDonostia International Physics Center. 20018, Donostia-San Sebastián. Spain

e-mail: vpostils@gmail.com

The oxidation state (OS) is one of the most fundamental chemical concepts. For the last two centuries it has been widely used for the characterization of compounds (mostly inorganic) and for the rationalization, categorization, and prediction of chemical reactivity. However, the OS concept has evolved over the years, the last revision by IUPAC organization being recently provided. [1] In this last revision, IUPAC introduces a new definition of the OS concept and conventional algorithms for its determination. [2]

Likewise, there have been several attempts to derive the OS by theoretical methods and to connect it with a physical quantity. There is a confusion in the literature concerning the concepts of oxidation state, atomic charge and ionicity. A first critical and necessary step towards the design of a quantum mechanical tool to determine the OS involves a throughout examination of them. All these concepts are related to the electron distribution around atoms but there is no consensus on how to partition charge densities to obtain them. Considering the recent work done by the IUPAC organization, the time is ripe for a revision of the determination of OSs by theoretical techniques.

In the presentation I will revise the different strategies to infer the OS with theoretical techniques. I will mainly focus on the differences between OSs and partial atomic charges, and on the attempts to derive OSs from first principles. Among the proposed quantum mechanical tools that seek to recover the simplistic picture of the OS concept that assigns an integer number of electrons to each atom (as opposed to the non-integer number of electrons provided by atomic charges), i.e., the use of centroids of localized orbitals,[3] the Localized Orbital Bonding Analysis (LOBA) developed by Thom et al.,[4] the use of projection techniques on auxiliary basis,[5] and the use of Effective Oxidation States (EOS),[6] I will focus on the last one. The EOS method has been developed at the University of Girona, and it is the only one tested in a wide range of molecules. [7] It can be implemented in any quantum method for which the first-order reduced density matrix can be obtained.

[1] a) P. Karen, P. McArdle, J. Takats, Pure Appl. Chem. 2014, 86, 1017-1081. b) P. Karen, Angew. Chem. Int. Ed. 2015, 54, 4716-4726.

[2] a) P. Karen, P. McArdle, J. Takats, Pure Appl. Chem. 2016, 88, 831-839. B) IUPAC. Compendium of Chemical Terminology, 2nd ed. (the “Gold Book”). https://goldbook.iupac.org/html/O/O04365.html

[3] P. H.-L. Sit, F. Zipoli, J. Chen, C. Car, M. H. Cohen, A. Selloni, Chem. A. Eur. J. 2011, 17, 12136-12143. b) P. Vidossich, A. Lledós, Dalton Trans. 2014, 43, 11145.

[4] A. J. W. Thom, E. J. Sundstrom, M. Head-Gordon, Phys. Chem. Chem. Phys. 2009, 11, 11297-11304.

[5] P. H.-L. Sit, R. Car, M. H. Cohen, A. Selloni, Inor. Chem. 2011, 50, 91-105.

[6] E. Ramos-Córdoba, V. Postils, P. Salvador, J. Chem. Theory Comput. 2015, 11, 1501-1508.

[7] V. Postils, C. Delgado-Alonso, J. M. Luis, P. Salvador, Angew. Chem. Int. Ed. 2018, 57, 1-6.

A Novel Signature of Dispersion Interactions: Intracule functions. Mireia Via-Nadal, Mauricio Rodríguez-Mayorga, Eloy Ramos-Cordoba, Eduard Matito It is well known that the leading term in the distance-based London expansion of the van der Waals (vdW) energy for atomic and molecular dimers decays as 1/R⁶, being R the dimer distance. By means of perturbation theory, we find the leading term in the distance-based expansion of the intracule pair density at the interatomic distance, which unveils a universal 1/R³ decay. This dependency is less prone to numerical errors than the 1/R⁶ dependency. As well, this signature of van der Waals interactions can be directly used in the construction of approximate pair density and energy functionals including vdW corrections. Ref. Mireia Via-Nadal, Mauricio Rodríguez-Mayorga and Eduard Matito. Phys. Rev. A 96(2017), 050501(R)

Natural Orbital Functional Theory Ion Mitxelena Natural Orbital Functional Theory (NOFT) has shown to be able to capture properly the static correlation, due to the multireference character of the method, and to overcome many problems that are inherent to DFT, due to having exactly defined the kinetic energy functional. Imposing N-representability conditions on the reconstruction of the electron-electron interaction energy functional, M. Piris and co-workers have been able to produce many approximations, known in the literature as PNOFi (i=1,7)[1,2], that yield accurate results for molecular systems, as well as the Hubbard model [3,4]. Indeed, a recent study [5] based on the Hubbard model has been crucial to determine a phase indeterminacy appearing in the bottom-up construction of energy functionals. Recently, we have shown that PNOFi not only produce relative accurate energies, but also equilibrium geometries [6,7] that compare with CCSD with respect to the experiment. These developments, together with many improvements on the numerical algorithms related to solving the equations needed to compute the natural orbitals and corresponding occupation numbers, will be included in a new software package called DoNOF, intended to be a tool to carry out electronic structure calculations based on most sophisticated NOF approximations. [1] M. Piris et al. IJQC 114, 1169(2014) [2] M. Piris PRL 119, 063002 (2017) [3] I. Mitxelena et al. JPCM 29, 42, 425602 (2017) [4] I. Mitxelena et al. JPCM 30 (2018) 089501 [5] I. Mitxelena et al. EPJ B (2018) 91: 109 [6] I. Mitxelena et al. JCP 146, 014102 (2017) [7] I. Mitxelena et al. J. Math Chem. (2018) 56: 1445

New tool to describe the aromaticity in large systems Irene Casademont-Reig,(a,b) Tatiana Woller,(c) Julia Contreras-García,(d) Eloy Ramos-Cordoba,(a,b) Mercedes Alonso,(c) Miquel Torrent-Sucarrat,(a,b,e) Eduard Matito,(b,e) a) Kimika Fakultatea, Euskal Herriko Unibertsitatea (UPV/EHU), 20018. Donostia, Euskadi, Spain. b) Donostia International Physics Center (DIPC),20018. Donostia, Euskadi, Spain. c) Eenheid Algemene Chemie (ALGC). Vrije Universiteit Brussel (VUB), Pleinlaan 2, 1050 Brussels (Belgium). d) Sorbonne Universités, UPMC Univ. Paris, UMR 7616 Laboratoire de Chimie Théorique, CNRS, UMR 7616, LCT 75005, Paris (France). e) Ikerbasque, Basque Foundation for Science, María Díaz de Haro 3, 6o, 48013 Bilbao, Euskadi, Spain. Aromaticity is a multifold property[1] that is useful to understand the electronic structure of large systems. It is recommended to study the aromaticity of a system using a set of descriptors based on different criteria.[2] In this work, we introduce a new electronic aromaticity index, AV1245,[3] consisting of an average of the 4-center multicenter indices (MCI) along the ring, and its minimum (AVmin)[4] in order to study the aromaticity of large circuits and to find the most conjugated pathway in the molecule. First, we will compare the abilty of different aromaticity descriptors to analyze the different conjugated circuits that present simple porphyrinoids and demonstrate that, among several aromaticity descriptors, only AVmin is capable of identifying the most conjugated pathway.[5] Second, we will show that AV1245 can reveal the local and global changes of aromaticity among the different studied oxidations states of a nanoring[6] as well as the role of the connectors between the porphyrins.[7] This new tool opens the possibilty to study electron conjugation and aromaticity in porphyrinoids, providing the most and the least conjugated fragments in the macrocycle. References [1] Katritzky, A. R., et al., J. Am. Chem. Soc. 1989, 111, 7. [2] Feixas, F., et al., Chem. Soc. Rev. 2015, 44, 6434. Torrent-Sucarrat, M., et al., Chem.-Eur. J., 2005, 11, 6024. Feixas, F., et al., J. Comput. Chem. 2008, 29, 1543. Alonso, M., et al., J. Comput. Chem. 2010, 31, 917. [3] Matito, E. Phys. Chem. Chem. Phys. 2016, 18, 11839. [4] García-Fernández, C., et al., J. Phys. Chem. C. 2017, 121, 27118. [5] Casademont-Reig, I., et al., Phys. Chem. Chem. Phys. 2018, 20, 2787. [6] Peeks, M.D., et al., Nature. 2017, 541, 200. [7] Casademont-Reig, I., et al., in preparation.

Extracting the phonon anharmonic properties from molecular dynamics simulations using DynaPhoPy code Abel Carreras A

Donostia International Physics Center, Paseo Manuel de Lardizabal, 4, 20018 Donostia-San Sebastián, Euskadi, Spain A) Anharmonicity is responsible to important thermodynamics properties such as thermal conductivity and thermal expansion. From the theoretical point of view, anharmonicity is defined as a deviation with respect to the harmonic behavior producing a change on the phonon frequencies (frequency shift) and adding width around the mean value (linewidths). Dynaphopy[1] is a code that allows to calculate the phonon renormalized frequency and linewidths from canonical ensemble molecular dynamics (MD) trajectories using the mode decomposition technique[2]. It is able to study strongly anharmonic materials at high temperatures, which cannot be dealt with by other methodologies such as perturbation theory. This software stands on well-established methods, therefore it is robust and applicable to automated systematic research. This technique consists in projecting the MD trajectory into the individual phonon modes coordinates obtained from harmonic lattice dynamics calculation. This way is possible to recover the phonon anharmonic frequencies as well as calculating the phonon linewidths from the power spectrum of each projection. We have tested DynaPhoPy by calculating the microscopic phonon properties of crystalline silicon. [1] http://abelcarreras.github.io/DynaPhoPy/ [2] Sun T, Zhang D B & Wentzcovitch R M. Phys. Rev. B, 89 (2014)

Quantum molecular predictions from classical paths L. Bonnet CNRS, Univ. Bordeaux, Institut des Sciences Moléculaires, UMR 5255, F-33400, Talence The goal of the talk is to show how one may approximate the quantum predictions in molecular dynamics [1] and spectroscopy [2] by replacing tough wave propagations by friendly trajectory calculations. [1] L. Bonnet, ''Semiclassical initial value theory of rotationally inelastic scattering: Some remarks on the phase index in the interaction picture'', J. Chem. Phys. 148, 194104 (2018) [2] G. Di Liberto, R. Conte, M. Ceotto, ''Divide and conquer semiclassical molecular dynamics: An application to water clusters'', J. Chem Phys. 148, 104302 (2018)