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Mitev, Pavlin D.
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Publications (10 of 30) Show all publications
Kebede, G., Mitev, P. D., Broqvist, P., Kullgren, J. & Hermansson, K. (2018). Hydrogen-Bond Relations for Surface OH Species [Review]. The Journal of Physical Chemistry C, 122(9), 4849-4858
Open this publication in new window or tab >>Hydrogen-Bond Relations for Surface OH Species
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2018 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 122, no 9, p. 4849-4858Article, book review (Refereed) Published
Abstract [en]

This paper concerns thin water films and their hydrogen-bond patterns on ionic surfaces. As far as we are aware, this is the first time H-bond correlations for surface water and hydroxide species are presented in the literature while hydrogen-bond relations in the solid state have been scrutinized for at least five decades. Our data set, which was derived using density functional theory, consists of 116 unique surface OH groups–intact water molecules as well as hydroxides–on MgO(001), CaO(001) and NaCl(001), covering the whole range from strong to weak to no H-bonds. The intact surface water molecules are found to always be redshifted with respect to the gas-phase water OH vibrational frequency, whereas the surface hydroxide groups are either redshifted (OsH) or blueshifted (OHf) compared to the gas-phase OH frequency. The surface H-bond relations are compared with the traditional relations for bulk crystals. We find that the “ν(OH) vs R(H···O)” correlation curve for surface water does not coincide with the solid state curve: it is redshifted by about 200 cm–1 or more. The intact water molecules and hydroxide groups on the ionic surfaces essentially follow the same H-bond correlation curve.

Place, publisher, year, edition, pages
Uppsala: , 2018
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-347220 (URN)10.1021/acs.jpcc.7b10981 (DOI)000427331300013 ()
Funder
Swedish Research Council
Available from: 2018-03-27 Created: 2018-03-27 Last updated: 2018-05-31Bibliographically approved
Kebede, G., Mitev, P. D. & Briels, W. (2018). Red-shifting and blue-shifting OH groups on metal oxide surfaces: towards a unified picture. Physical Chemistry, Chemical Physics - PCCP, 20(18), 12678-12687
Open this publication in new window or tab >>Red-shifting and blue-shifting OH groups on metal oxide surfaces: towards a unified picture
2018 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 20, no 18, p. 12678-12687Article in journal (Refereed) Published
Abstract [en]

We analyse the OH vibrational signatures of water molecules and hydroxide ions on thin water films on MgO(001) and CaO(001), using DFT-generated anharmonic potential energy surfaces. We find that the OH stretching frequencies of intact water molecules on the surface are always downshifted with respect to the gas-phase species while the OH– groups are either upshifted or downshifted. Despite these differences, the main characteristics of the frequency shifts for all three types of surface OH groups (OHw, OsH and OHf) can be accounted for by one unified expression involving the in situ electric field from the surrounding environment, and the molecular properties of the vibrating species (H2O or OH–). The origin behind the different red- and blueshift behaviour can be traced back to the fact that the molecular dipole moment of a gas-phase water molecule increases when an OH bond is stretched, but the opposite is true for the hydroxide ion. We propose that familiarity with the relations presented here will help surface scientists in the interpretation of vibrational OH spectra for thin water films on ionic crystal surfaces.

National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-347218 (URN)10.1039/C8CP00741A (DOI)000431825300035 ()29697122 (PubMedID)
Funder
eSSENCE - An eScience CollaborationSwedish Research Council
Available from: 2018-03-27 Created: 2018-03-27 Last updated: 2018-08-16Bibliographically approved
Broqvist, P., Kullgren, J., Zhang, C., Du, D., Hermansson, K., Kebede, G., . . . Mitev, P. D. (2017). Chemistry of Complex Materials. In: : . Paper presented at Swedish e-Science Academy 2017.
Open this publication in new window or tab >>Chemistry of Complex Materials
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2017 (English)Conference paper, Poster (with or without abstract) (Other academic)
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-338355 (URN)
Conference
Swedish e-Science Academy 2017
Available from: 2018-01-08 Created: 2018-01-08 Last updated: 2018-01-08
Zukowski, S. R., Mitev, P. D., Hermansson, K. & Ben-Amotz, D. (2017). CO2 Hydration Shell Structure and Transformation [Letter to the editor]. Journal of Physical Chemistry Letters, 8(13), 2971-2975
Open this publication in new window or tab >>CO2 Hydration Shell Structure and Transformation
2017 (English)In: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 8, no 13, p. 2971-2975Article in journal, Letter (Refereed) Published
Abstract [en]

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.

National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:uu:diva-327953 (URN)10.1021/acs.jpclett.7b00971 (DOI)
Funder
Swedish Research CouncileSSENCE - An eScience Collaboration
Available from: 2017-08-14 Created: 2017-08-14 Last updated: 2017-10-13Bibliographically approved
Mitev, P. D., Briels, W. & Hermansson, K. (2017). CO2 in water from experiment and calculations. In: : . Paper presented at Swedish e-Science Academy 2017.
Open this publication in new window or tab >>CO2 in water from experiment and calculations
2017 (English)Conference paper, Poster (with or without abstract) (Other academic)
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-338361 (URN)
Conference
Swedish e-Science Academy 2017
Available from: 2018-01-08 Created: 2018-01-08 Last updated: 2018-01-08
Kebede, G. G., Spångberg, D., Mitev, P. D., Broqvist, P. & Hermansson, K. (2017). Comparing van der Waals DFT methods for water on NaCl(001) and MgO(001). Journal of Chemical Physics, 146, Article ID 064703.
Open this publication in new window or tab >>Comparing van der Waals DFT methods for water on NaCl(001) and MgO(001)
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2017 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 146, article id 064703Article in journal (Other (popular science, discussion, etc.)) Published
National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:uu:diva-315592 (URN)10.1063/1.4971790 (DOI)000394577400037 ()28201901 (PubMedID)
Funder
Swedish Research CouncilSwedish National Infrastructure for Computing (SNIC)
Available from: 2017-02-15 Created: 2017-02-15 Last updated: 2018-04-11Bibliographically approved
Kullgren, J., Wolf, M. J., Mitev, P. D., Hermansson, K. & Briels, W. J. (2017). Defect cluster at the CeO2(111) surface: A combined DFT and Monte-Carlo study. In: : . Paper presented at Annual meeting of the Swedish Chemical Society Theoretical Chemistry Section, Göteborg 16-18 August.
Open this publication in new window or tab >>Defect cluster at the CeO2(111) surface: A combined DFT and Monte-Carlo study
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2017 (English)Conference paper, Oral presentation with published abstract (Other academic)
National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:uu:diva-338316 (URN)
Conference
Annual meeting of the Swedish Chemical Society Theoretical Chemistry Section, Göteborg 16-18 August
Available from: 2018-01-08 Created: 2018-01-08 Last updated: 2018-01-12Bibliographically approved
Kullgren, J., Wolf, M. J., Mitev, P. D., Hermansson, K. & Briels, W. J. (2017). DFT-based Monte Carlo Simulations of Impurity Clustering at CeO2(111). The Journal of Physical Chemistry C, 121(28), 15127-15134
Open this publication in new window or tab >>DFT-based Monte Carlo Simulations of Impurity Clustering at CeO2(111)
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2017 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 121, no 28, p. 15127-15134Article in journal (Refereed) Published
Abstract [en]

The interplay between energetics and entropy in determining defect distributions at ceria(111) is studied using a combination of DFT+U and lattice Monte Carlo simulations. Our main example is fluorine impurities, although we also present preliminary results for surface hydroxyl groups. A simple classical force-field model was constructed from a training set of DFT+U data for all symmetrically inequivalent (F-)(n)(Ce3+)(n) nearest-neighbor clusters with n = 2 or 3. Our fitted model reproduces the DFT energies well. We find that for an impurity concentration of 15% at 600 K, straight and hooked linear fluorine clusters are surprisingly abundant, with similarities to experimental STM images from the literature. We also find that with increasing temperature the fluorine cluster sizes show a transition from being governed by an attractive potential to being governed by a repulsive potential as a consequence of the increasing importance of the entropy of the Ce3+ ions. The distributions of surface hydroxyl groups are noticeably different.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2017
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-332849 (URN)10.1021/acs.jpcc.7b00299 (DOI)000406355700016 ()
Funder
Swedish Research Council
Available from: 2017-11-08 Created: 2017-11-08 Last updated: 2017-11-08Bibliographically approved
Wolf, M. J., Hermansson, K., Mitev, P. D., Briels, W. & Kullgren, J. (2017). Fluorine clusters at CeO2(111) - A DFT+U and Monte Carlostudy. In: : . Paper presented at Towards Reality in Nanoscale Materials IX Nanoscale Materials for Warfare Agent Detection: Nanoscience for Security 13th – 16th February 2017 Levi, Finland.
Open this publication in new window or tab >>Fluorine clusters at CeO2(111) - A DFT+U and Monte Carlostudy
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2017 (English)Conference paper, Oral presentation with published abstract (Other academic)
Abstract [en]

STM experiments on CeO2(111) reveal depressions in the surface oxygen sub-lattice which are observed to form clusters of various shapes and sizes [1].While these depressions were assumed to be oxygen vacancies, subsequent DFTcalculations have indicated that clusters of oxygen vacancies are energeticallyunstable [2-4]. Recently, we showed theoretically that fluorine impurities shouldappear almost identical to oxygen vacancies in STM experiments, but that theirproperties are more in line with those of the defects observed in experiments [5].Here, I will present the results of a further investigation into the distribution ofF impurity clusters at CeO2(111), using a combination of DFT+U calculations,and Monte Carlo sampling based on a simple but accurate pair potential whichwas fitted to the DFT results. The distribution is characterised in terms of thenumber of clusters of a certain size, and also on their topology, i.e. whetherthey are compact or open/linea r. Our results compare favourably with theexperiments, and also exhibit some interesting physics in their own right.

[1] F. Esch et al., Science 309, 752 (2005).[2] J. Conesa, Cat. Today 143, 315 (2009).[3] C. Zhang et al., Phys. Rev. B 79, 075433 (2009).[4] X.-P. Wu & X.-Q. Gong, Phys. Rev. Lett. 116, 086102 (2016).[5] J. Kullgren, M. J. Wolf et al., Phys. Rev. Lett. 112, 156102 (2014).

National Category
Nano Technology
Identifiers
urn:nbn:se:uu:diva-338364 (URN)
Conference
Towards Reality in Nanoscale Materials IX Nanoscale Materials for Warfare Agent Detection: Nanoscience for Security 13th – 16th February 2017 Levi, Finland
Available from: 2018-01-08 Created: 2018-01-08 Last updated: 2018-02-22Bibliographically approved
Kebede, G., Mitev, P. D. & Hermansson, K. (2017). OH. In: : . Paper presented at Swedish Theoretical Chemistry 2017 – Bridging Gaps.
Open this publication in new window or tab >>OH
2017 (English)Conference paper, Poster (with or without abstract) (Other academic)
National Category
Materials Chemistry Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-338366 (URN)
Conference
Swedish Theoretical Chemistry 2017 – Bridging Gaps
Available from: 2018-01-08 Created: 2018-01-08 Last updated: 2018-01-08
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