Author Archives: Pavlin Mitev

Fifty Shades of Water: Benchmarking DFT Functionals against Experimental Data for Ionic Crystalline Hydrates

Authors: Getachew Kebede, Peter Broqvist, Anders Eriksson, and Kersti Hermansson

We propose that crystalline ionic hydrates constitute a valuable resource for benchmarking theoretical methods for aqueous ionic systems. Many such structures are known from the experimental literature, and they contain a large variety of water–water and ion–water structural motifs. Here we have collected a data set (CRYSTALWATER50) of 50 structurally unique “in-crystal” water molecules, involved in close to 100 nonequivalent O–H···O hydrogen bonds. A dozen well-known DFT functionals were benchmarked with respect to their ability to describe these experimental structures and their OH vibrational frequencies. We find that the PBE, RPBE-D3, and optPBE-vdW methods give the best H-bond distances and that anharmonic OH frequencies generated from B3LYP//optPBE-vdW energy scans outperform the other methods, i.e., here we performed B3LYP energy scans along the OH stretching coordinate while the rest of the structure was kept fixed at the optPBE-vdW-optimized positions

J. Chem. Theory Comput. 15, p. 584, 2019
DOI: 10.1021/acs.jctc.8b00423


Inter-division beach volley tournament – first place award


First Place Award on the Ångström Inter-division beach volley tournament, 21 August 2018

Ageo Meier de Andrade and Akshay Krishna Ammothum Kandy 



Ageo Meier de Andrade – 2nd prize for poster at CCP5

Ageo Meier de Andrade was awarded 2nd prize for his poster presentation at the CPP5 school, Lancaster University, 9-17 July 2018.


Seminar: “Mineral/water interfaces characterized by Ab Initio Molecular Dynamics: making the link between structure and SFG vibrational spectroscopy”

Time: Thursday 17 May 2018 at 14.15
Room: Å 4001

Title: “Mineral/water interfaces characterized by Ab Initio Molecular Dynamics: making the link between structure and SFG vibrational spectroscopy”

Speaker: Professor Marie-Pierre Gaigeot
LAMBE UMR 8587, Laboratoire Analyse et Modélisation pour la Biologie et l’Environnement, Université d’Evry val d’Essonne, Paris – Université Paris Saclay, France,

In this presentation, we will review our recent theoretical works on the characterization of mineral/liquid water interfaces, i.e. silica/water (crystalline and amorphous) and alumina/water interfaces, making the link between structure and non-linear SFG (Sum Frequency Generation) experiments. Non-linear SFG spectroscopy in the 3000-4000 cm-1 spectral domain is indeed one method of choice to probe complex inhomogeneous solid/liquid and liquid/air interfaces. Although an extremely powerful technique, the detailed interpretation of the experimental signatures requires associated calculations. This is the challenge we have been tackling over the past 5 years, applying Ab Initio DFT-based molecular dynamics simulations (DFT-MD).

I will illustrate here some of our recent works showing how to separate vibrational signatures arising from the different layers of water at the interface, how to provide a direct interpretation of the H-Bond networks at play at interfaces (water-water vs solid-water networks), including our recent works unraveling 2-dimensional interfacial water networks, how to define the only three spatial regions of interest at any charged interfaces (BIL, Binding Interfacial Layer; DL, Diffuse Layer; Bulk) and how to universally interpret/assign SFG vibrational bands from these three regions, including χ2 and χ3 contributions into the theoretical signals. We will also show how our deconvolution schemes for SFG spectral interpretation provide direct knowledge of the isoelectric point at any aqueous surface and direct knowledge of the formation of an Electric Double Layer (EDL) when aqueous ionic solutions are considered at the interface. We will unravel trends in going from hydrophobic to hydrophilic surfaces at the interface with liquid water.

Acknowledgments: Collaborative works with Prof. Y. Ron Shen at the University of California at Berkeley, USA, Prof E. Borguet at Temple University, USA, Dr E. Backus, Max Planck Institute in Mainz, Germany. Works achieved with PhD/Post-Doc students S. Pezzotti, D. Galimberti, M. Pfeiffer-Laplaud, L. Potier, F. Siro Brigiano, A. Cimas.


Unravelling in-situ formation of highly active mixed metal oxide CuInO2 nanoparticles during CO2 electroreduction

Authors: Roghayeh Imani, Zhen Qiu, Reza Younesi, Meysam Pazoki, Daniel L.A. Fernandes, Pavlin D. Mitev, Tomas Edvinsson, Haining Tian

Technologies and catalysts for converting carbon dioxide (CO2) to immobile products are of high interest to minimize greenhouse effects. Copper(I) is a promising catalytic active state of copper but hampered by the inherent instability in comparison to copper(II) or copper(0). Here, we report a stabilization of the catalytic active state of copper(I) by the formation of a mixed metal oxide CuInO2 nanoparticle during the CO2electroreduction. Our result shows the incorporation of nanoporous Sn:In2O3 interlayer to Cu2O pre-catalyst system lead to the formation of CuInO2 nanoparticles with remarkably higher activity for CO2 electroreduction at lower overpotential in comparison to the conventional Cu nanoparticles derived from sole Cu2O. Operando Raman spectroelectrochemistry is employed to in-situ monitor the process of nanoparticles formation during the electrocatalytic process. The experimental data are collaborated with DFT calculations to provide insight into the electro-formation of the type of Cu-based mixed metal oxide catalyst during the CO2 electroreduction, where a formation mechanism via copper ion diffusion across the substrate is suggested.

Nano Energy, Volume 49, July 2018, Pages 40-50

Maximally resolved anharmonic OH vibrational spectrum of the water/ZnO(10-10) interface from a high-dimensional neural network potential

Authors:  Vanessa Quaranta, Matti Hellström, Jörg Behler, Jolla Kullgren, Pavlin D. Mitev, and Kersti Hermansson

Unraveling the atomistic details of solid/liquid interfaces, e.g., by means of vibrational spectroscopy, is of vital importance in numerous applications, from electrochemistry to heterogeneous catalysis. Water-oxide interfaces represent a formidable challenge because a large variety of molecular and dissociated water species are present at the surface. Here, we present a comprehensive theoretical analysis of the anharmonic OH stretching vibrations at the water/ZnO(10-10) interface as a prototypical case. Molecular dynamics simulations employing a reactive high-dimensional neural network potential based on density functional theory calculations have been used to sample the interfacial structures. In the second step, one-dimensional potential energy curves have been generated for a large number of configurations to solve the nuclear Schrödinger equation. We find that (i) the ZnO surface gives rise to OH frequency shifts up to a distance of about 4 Å from the surface; (ii) the spectrum contains a number of overlapping signals arising from different chemical species, with the frequencies decreasing in the order ν(adsorbed hydroxide) > ν(non-adsorbed water) > ν(surface hydroxide) > ν(adsorbed water); (iii) stretching frequencies are strongly influenced by the hydrogen bond pattern of these interfacial species. Finally, we have been able to identify substantial correlations between the stretching frequencies and hydrogen bond lengths for all species.

The Journal of Chemical Physics, 148, 241720 (2018);

Database: H-bond and electric field correlations for water in highly hydrated crystals

Database: H-bond and electric field correlations for water in highly hydrated crystals

Anik Sen, Pavlin D. Mitev, Anders Eriksson, and Kersti Hermansson,
International Journal of Quantum Chemistry
116, ( 2016), 67-80

ASE format database with all structures, Bader and Wannier analysis, and OH stretching frequency published.

Read more…

CO2 Hydration Shell Structure and Transformation

Authors: Samual R. Zukowski, Pavlin D. Mitev, Kersti Hermansson, and Dor Ben-Amotz

The hydration-shell of CO2 is characterized using Raman multivariate curve resolution (Raman-MCR) spectroscopy combined with ab initio molecular dynamics (AIMD) vibrational density of states simulations, to validate our assignment of the experimentally observed high-frequency OH band to a weak hydrogen bond between water and CO2. Our results reveal that while the hydration-shell of CO2 is highly tetrahedral, it is also occasionally disrupted by the presence of entropically stabilized defects associated with the CO2-water hydrogen bond. Moreover, we find that the hydration-shell of CO2 undergoes a temperature-dependent structural transformation to a highly disordered (less tetrahedral) structure, reminiscent of the transformation that takes place at higher temperatures around much larger oily molecules. The biological significance of the CO2 hydration shell structural transformation is suggested by the fact that it takes place near physiological temperatures.

J. Phys. Chem. Lett., 8 (13), 2017, pp 2971–2975
DOI: 10.1021/acs.jpclett.7b00971

The 2017 eSSENCE meeting on “Multiscale modelling of materials and molecules”

The 2017 eSSENCE meeting on
“Multiscale modelling of materials and molecules”
will take place 12-14 June in Uppsala

The eSSENCE e-science program arranges a materials modelling meeting
with our sister program SeRC and other e-science actors, June 12-14 2017.
We expect an interesting mix of method/model development and applications.
The meeting, including all meals, is free of charge.
The website address is
Very welcome to the meeting! The registration is now open.

Kersti Hermansson, Peter Broqvist and team,

Comparing van der Waals DFT methods for water on NaCl(001) and MgO(001)

Authors: Getachew G. Kebede, Daniel Spångberg, Pavlin D. Mitev, Peter Broqvist, and   Kersti Hermansson

In this work, a range of van der Waals type density functionals are applied to the H2O/NaCl(001) and H2O/MgO(001) interface systems to explore the effect of an explicit dispersion treatment. The functionals we use are the self-consistent vdW functionals vdW-DF, vdW-DF2, optPBE-vdW, optB88-vdW, optB86b-vdW, and vdW-DF-cx, as well as the dispersion-corrected PBE-TS and PBE-D2 methods; they are all compared with the standard PBE functional. For both NaCl(001) and MgO(001), we find that the dispersion-flavoured functionals stabilize the water-surface interface by approximately 20%-40% compared to the PBE results. For NaCl(001), where the water molecules remain intact for all overlayers, the dominant contribution to the adsorption energy from “density functional theory dispersion” stems from the water-surface interactions rather than the water-water interactions. The optPBE-vdW and vdW-DF-cx functionals yield adsorption energies in good agreement with available experimental values for both NaCl and MgO. To probe the strengths of the perturbations of the adsorbed water molecules, we also calculated water dipole moments and found an increase up to 85% for water at the MgO(001) surface and 70% at the NaCl(001) surface, compared to the gas-phase dipole moment.

The Journal of Chemical Physics 146, 064703 (2017);