ILMAT5 presentation

LINK to the PRESENTATION

Abstract

In this work [0], we have applied the DFT-based delta Kohn–Sham (ΔKS) method to ion pairs in a vacuum to obtain X-ray pho­toelectron spectra of corresponding ionic liquids (IL). On the example of forty ion pairs, we demonstrate how the core level binding energy (BE) values can be calcu­lated and used to plot theo­retical spectra at a low computational cost. Furthermore, we compare the ΔKS results, 1s Kohn–Sham orbital energies, and atomic charges against the experi­mental X-ray photoelec­tron data. Recently, in connection to the electro­chemical application in the super­capacitors, we have measured spectra for EMImBF4 and EMImB(CN)4 ionic liquids at the carbon–IL interface [1–3]. Other experimental spectra were obtained from the literature [4,5]. Both the ΔKS BE values and the 1s Kohn–Sham orbital energies show a correlation, yet with a different order of the BEs assigned to spe­cific atoms. We find that neither DDEC6 nor Bader charges cor­relate with the experi­mental data. Thus, the DFT calculations of 1s Kohn–Sham orbital energies provide the fastest way of pre­dicting the XPS spectra. However, more detailed experimental studies are required to resolve the right order of the BE values and its rela­tion to the atomistic structure of the ILs. The ΔKS calculations provide the most precise estimations of the BEs. Herewith, they also demand more resources and cause computa­tional difficulties discussed in the presenta­tion. Besides the prediction power, a robust computational method can help in intepre­tating experimental data when the appropriate reference values are either not available nor directly applicable. Thus, the ΔKS method can find its application in various fields of physics and chemistry where the XPS is used for re­solving electronic and geometric structures of pure ILs, their mixtures, and at interfaces.

In this work, we have applied the DFT-based delta Kohn–Sham (ΔKS) method to ion pairs in a vacuum to obtain X-ray pho­toelectron spectra of corresponding ionic liquids (IL). On the example of forty ion pairs, we demonstrate how the core level binding energy (BE) values can be calcu­lated and used to plot theo­retical spectra at a low computational cost. Furthermore, we compare the ΔKS results, 1s Kohn–Sham orbital energies, and atomic charges against the experi­mental X-ray photoelec­tron data. Recently, in connection to the electro­chemical application in the super­capacitors, we have measured spectra for EMImBF4 and EMImB(CN)4 ionic liquids at the carbon–IL interface [1–3]. Other experimental spectra were obtained from the literature [4,5]. Both the ΔKS BE values and the 1s Kohn–Sham orbital energies show a correlation, yet with a different order of the BEs assigned to spe­cific atoms. We find that neither DDEC6 nor Bader charges cor­relate with the experi­mental data. Thus, the DFT calculations of 1s Kohn–Sham orbital energies provide the fastest way of pre­dicting the XPS spectra. However, more detailed experimental studies are required to resolve the right order of the BE values and its rela­tion to the atomistic structure of the ILs. The ΔKS calculations provide the most precise estimations of the BEs. Herewith, they also demand more resources and cause computa­tional difficulties discussed in the presenta­tion. Besides the prediction power, a robust computational method can help in intepre­tating experimental data when the appropriate reference values are either not available nor directly applicable. Thus, the ΔKS method can find its application in various fields of physics and chemistry where the XPS is used for re­solving electronic and geometric structures of pure ILs, their mixtures, and at interfaces.

[0] M. Lembinen, E. Nõmmiste, H. Ers, B. Docampo‐Álvarez, J. Kruusma, E. Lust, V.B. Ivaništšev, Calculation of core‐level electron spectra of ionic liquids, Int. J. Quantum Chem. 120 (2020). https://doi.org/10.1002/qua.26247.

[1] J. Kruusma, A. Tõnisoo, R. Pärna, E. Nõmmiste, I. Tallo, T. Romann, E. Lust, Electrochimica Acta 206 (2016) 419–426.

[2] J. Kruusma, A. Tõnisoo, R. Pärna, E. Nõmmiste, I. Kuusik, M. Vahtrus, I. Tallo, T. Romann, E. Lust, J. Electrochem. Soc. 164 (2017) A3393–A3402.

[3] A. Tõnisoo, J. Kruusma, R. Pärna, A. Kikas, M. Hirsimäki, E. Nõmmiste, E. Lust, J. Electrochem. Soc. 160 (2013) A1084–A1093.

[4] A. Foelske-Schmitz, D. Weingarth, R. Kötz, Surf. Sci. 605 (2011) 1979–1985.

[5] I.J. Villar-Garcia, E.F. Smith, A.W. Taylor, F. Qiu, K.R.J. Lovelock, R.G. Jones, P. Licence, Phys. Chem. Chem. Phys. 13 (2011) 2797–2808.

The dark side of submitting in LaTeX

Point 1. On the publishers portals, LaTeX looks old-fashioned. The compilation seemed romantic in the early students years, but currently it looks awful to me: LaTeX -> BibTeX -> LaTeX -> DVI -> PS -> PDF. ShareLaTeX is great, yet to submit a paper one has to return to the old-school compilation.

Point 2. Grammarly does not work with bare TeX even in ShareLaTeX. There is so much space for improvement, where publishers could significantly contribute. Do they?

Point 3. Vector figures are great. Why do publishers ask for eps? The encapsulated postscript is outdated. For instance, it does not support transparency and also gradients, to a certain extent.

Predictions of Physicochemical Properties of Ionic Liquids with DFT

We have published an article in Computation, where we discuss predicting both static and dynamic physicochemical properties of ionic liquids with density functional theory. We prepared a workflow using NaRIBaS and conducted the calculations with 48 common ionic pairs. Thence, we estimated relevant properties for practical electrochemical applications, such as electrochemical stability and viscosity.

This work is an example how a simplistic computational model can be used in combination with informatics techniques to obtain relevant information about the ionic liquids. It can be found at the MDPI Journal website (Computation 2016, 4(3), 25; doi:10.3390/computation4030025).


Figure 6 from the article.
Figure 6 from the article. The relation between the electrochemical stability window (EW) and the estimated activation energy of viscosity (Eaest).

Soaked to the skin: tuning ionic liquids for electrochemical devices

A post in JPhys+ about our recent article: Researchers at the Universities of Santiago de Compostela, A Coruña, Tartu, Stratchclyde and Cambridge, shed light on the structure of the electrified interface in mixtures of contaminated ionic liquids in their recently published JPCM letter.

Soaked to the skin: tuning ionic liquids for electrochemical devices

The article is published here: http://iopscience.iop.org/article/10.1088/0953-8984/28/46/464001

P.S. This publication became possible thanks to the COST CM1206.

P.P.S. Finally they have corrected the authors names!

 

6th Baltic Electrochemistry Conference

The 6th Baltic Electrochemistry Conference held in Helsinki, Finland during a period of 14-17 June and collects researchers dedicated to the science and technology of electrochemistry around the Baltic. This conference provides a forum for individuals from research organizations and companies to learn about the latest developments in this rapidly evolving field, to discuss with renowned experts and to build their networks in an informal and friendly atmosphere. The conference covers all forms of electrochemistry, including, but not limited to experimental and theoretical aspects of charge transfer at electrochemical interfaces, electrochemical materials science, and electrocatalysis. In addition, emergent technologies like electrodeposition of nanomaterials and functionalized electrodes, and electrochemical nanostructuring feature along with related poster presentation sessions.

I am taking part in these conference with the poster presentation “DFT-based modeling of associates of ionic liquid ions” where discuss the ability of prediction properties of novel type electrolytes by applying the results of the DFT calculations of simpler ionic associates. For this reason, the effect of the self-interaction and dispersion corrections on the results of DFT calculations for 48 ionic associates has been investigated [1]. The magnitude of the corrections strongly depends on the anion choice and especially in the case of halide anions. It is very important to pay particular attention to that fact because ionic liquid mixture with the addition of halides has attracted attention as a possible electrolyte for supercapacitors [2].

[1] I. Lage-Estebanez, A. Ruzanov, J. M. García de la Vega, M. V. Fedorov and V. B. Ivaništšev, Self-interaction error in DFT-based modelling of ionic liquids, Phys. Chem. Chem. Phys., 18 (2016) 2175-2182.

[2] T. Tooming, T. Thomberg, L. Siinor, K. Tõnurist, A. Jänes, E. Lust, A type high capacitance supercapacitor based on mixed room temperature ionic liquids containing specifically adsorbed iodide anions, J. Electrochem.

Surprisingly open

Somehow I have missed the fact that a recently published paper on “Self-interaction error in DFT-based modelling of ionic liquids” is gold open-access dx.doi.org/10.1039/C5CP05922D. That is great! Thanks to the Universidad Autónoma de Madrid that paid the costs.

In this paper we investigate the influence of the self-interaction error (SIE) on dipole moments and interaction energies of ionic liquids. The reference level is MP2, yet we are already moving to the CCSD(T) level. Most importantly, the influence of the SIE of KS-DFT has been barely considered within the ionic liquid community, and the presented study addresses exactly this issue. Read the open access article and examine your-self what we have found dx.doi.org/10.1039/C5CP05922D.

P.S. The paper was prepared in ShareLaTeX mainly by me (Vladislav Ivaništšev) and Isabel Lage-Estebanez. In-time we will share some tips and tricks about organizing the real-time editing. Anton Ruzanov performed most of the analysis, visualization and plotting. Some know-how should be also shared soon.

An article submitted

An article titled “Electrochemical investigation of 1-ethyl-3-methylimidazolium bromide and tetrafluoroborate mixture at Bi(111) electrode interface” by Enn Lust, Carolin Siimenson, Meeri Lembinen, Ove Oll, Laura Läll, Marta Tarkanovskaja, Liis Siinor, Vladislav Ivaništšev, and Karmen Lust was submitted to JES.

What is so special about this article? First, the work presented is done in a joiful collaboration. Second, the computational results were obtained within a “DFT Calculations in Electrochemistry” course (LOKT.02.048), within a student project by Meeri and Marta. Well done!

Archive at arXiv

Recently two our articles were uploaded to arXiv. Our collaborator Satish Narayana Srirama prepared the first one:

http://arxiv.org/abs/1604.02788

While submitting the other, we encountered some problems when compiling the source tex-file. It turned out that one should add \pdfoutput=1 to get everything work. As a result, the second article was successfully archived at the arXiv:

http://arxiv.org/abs/1511.08078

Writing workshop

Thesis writing and, in general, academic writing is a skill. Not everyone has that skill, but certainly most can get it. To develop an understanding of the behaviours associated with successful writing, we organized a workshop with the help of AVOK – Centre for Academic Writing and Communication. Under the supervision of Djuddah A. J. Leijen, we started this four-hour workshop with Q&A followed by sessions about time management, in particular how to avoid procrastination, and, of course, grammar.

Continue reading “Writing workshop”