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Johansson, Börje
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Publications (10 of 268) Show all publications
Pasti, I. A., Jovanovic, A., Dobrota, A. S., Mentus, S. V., Johansson, B. & Skorodumova, N. V. (2018). Atomic adsorption on graphene with a single vacancy: systematic DFT study through the periodic table of elements. Physical Chemistry, Chemical Physics - PCCP, 20(2), 858-865
Open this publication in new window or tab >>Atomic adsorption on graphene with a single vacancy: systematic DFT study through the periodic table of elements
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2018 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 20, no 2, p. 858-865Article in journal (Refereed) Published
Abstract [en]

Vacancies in graphene present sites of altered chemical reactivity and open possibilities to tune graphene properties by defect engineering. The understanding of chemical reactivity of such defects is essential for successful implementation of carbon materials in advanced technologies. We report the results of a systematic DFT study of atomic adsorption on graphene with a single vacancy for the elements of rows 1-6 of the periodic table of elements (PTE), excluding lanthanides. The calculations have been performed using the PBE, long-range dispersion interaction-corrected PBE (PBE+D2 and PBE+D3) and non-local vdW-DF2 functionals. We find that most elements strongly bind to the vacancy, except for the elements of groups 11 and 12, and noble gases, for which the contribution of dispersion interaction to bonding is most significant. The strength of the interaction with the vacancy correlates with the cohesive energy of the elements in their stable phases: the higher the cohesive energy is, the stronger bonding to the vacancy can be expected. As most atoms can be trapped at the SV site we have calculated the potentials of dissolution and found that in most cases the metals adsorbed at the vacancy are more "noble" than they are in their corresponding stable phases.

National Category
Chemical Sciences Physical Sciences
Identifiers
urn:nbn:se:uu:diva-341487 (URN)10.1039/c7cp07542a (DOI)000419219700015 ()29238768 (PubMedID)
Available from: 2018-02-28 Created: 2018-02-28 Last updated: 2018-02-28Bibliographically approved
Pasti, I. A., Jovanovic, A., Dobrota, A. S., Mentus, S. V., Johansson, B. & Skorodumova, N. V. (2018). Atomic adsorption on pristine graphene along the Periodic Table of Elements - From PBE to non-local functionals. Applied Surface Science, 436, 433-440
Open this publication in new window or tab >>Atomic adsorption on pristine graphene along the Periodic Table of Elements - From PBE to non-local functionals
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2018 (English)In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 436, p. 433-440Article in journal (Refereed) Published
Abstract [en]

The understanding of atomic adsorption on graphene is of high importance for many advanced technologies. Here we present a complete database of the atomic adsorption energies for the elements of the Periodic Table up to the atomic number 86 (excluding lanthanides) on pristine graphene. The energies have been calculated using the projector augmented wave (PAW) method with PBE, long-range dispersion interaction corrected PBE (PBE+D2, PBE+D3) as well as non-local vdW-DF2 approach. The inclusion of dispersion interactions leads to an exothermic adsorption for all the investigated elements. Dispersion interactions are found to be of particular importance for the adsorption of low atomic weight earth alkaline metals, coinage and s-metals (11th and 12th groups), high atomic weight p-elements and noble gases. We discuss the observed adsorption trends along the groups and rows of the Periodic Table as well some computational aspects of modelling atomic adsorption on graphene.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2018
Keywords
Graphene, Adsorption, Atomic adsorption, Periodic Table of Elements, Dispersion interactions
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-350485 (URN)10.1016/j.apsusc.2017.12.046 (DOI)000425723100050 ()
Funder
Swedish Research Council, 348-2012-6196]Swedish Research Council, 2014-5993]Carl Tryggers foundation
Available from: 2018-05-17 Created: 2018-05-17 Last updated: 2018-05-17Bibliographically approved
Lee, J.-Y. -., Punkkinen, M. P., Schönecker, S., Nabi, Z., Kádas, K., Zolyomi, V., . . . Kwon, S. K. (2018). The surface energy and stress of metals. Surface Science, 674, 51-68
Open this publication in new window or tab >>The surface energy and stress of metals
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2018 (English)In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 674, p. 51-68Article in journal (Refereed) Published
Abstract [en]

We investigated surface properties of metals by performing first-principles calculations. A systematic database was established for the surface relaxation, surface energy (gamma), and surface stress (tau) for metallic elements in the periodic table. The surfaces were modeled by multi-layered slab structures along the direction of low-index surfaces. The surface energy gamma of simple metals decreases as the atomic number increases in a given group, while the surface stress tau has its minimum in the middle. The transition metal series show parabolic trends for both gamma and tau with a dip in the middle. The dip occurs at half-band filling due to a long-range Friedel oscillation of the surface charge density, which induces a strong stability to the Peierls-like transition. In addition, due to magnetic effects, the dips in the 3d metal series are shallower and deeper for gamma and tau respectively, than those of the 4d and 5d metals. The surface stress of the transition metals is typically positive, only Cr and Mn have a negative tau for the (100) surface facet, indicating that they are under compression. The light actinides have an increasing gamma trend according to the atomic number. The present work provides a useful and consistent database for the theoretical modelling of surface phenomena.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2018
Keywords
Surface relaxation, Surface energy, Surface stress, Density-functional theory calculations, Metals
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-356604 (URN)10.1016/j.susc.2018.03.008 (DOI)000432759200009 ()
Funder
Swedish Research CouncilSwedish Foundation for Strategic Research VINNOVA, 2014-03374Swedish Energy AgencyThe Swedish Foundation for International Cooperation in Research and Higher Education (STINT)Carl Tryggers foundation
Available from: 2018-08-03 Created: 2018-08-03 Last updated: 2018-08-03Bibliographically approved
Pasti, I. A., Johansson, B. & Skorodumova, N. V. (2018). Tunable reactivity of supported single metal atoms by impurity engineering of the MgO(001) support. Physical Chemistry, Chemical Physics - PCCP, 20(9), 6337-6346
Open this publication in new window or tab >>Tunable reactivity of supported single metal atoms by impurity engineering of the MgO(001) support
2018 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 20, no 9, p. 6337-6346Article in journal (Refereed) Published
Abstract [en]

Development of novel materials may often require a rational use of high price components, like noble metals, in combination with the possibility to tune their properties in a desirable way. Here we present a theoretical DFT study of Au and Pd single atoms supported by doped MgO(001). By introducing B, C and N impurities into the MgO(001) surface, the interaction between the surface and the supported metal adatoms can be adjusted. Impurity atoms act as strong binding sites for Au and Pd adatoms and can help to produce highly dispersed metal particles. The reactivity of metal atoms supported by doped MgO(001), as probed by CO, is altered compared to their counterparts on pristine MgO(001). We find that Pd atoms on doped MgO(001) are less reactive than on perfect MgO(001). In contrast, Au adatoms bind CO much more strongly when placed on doped MgO(001). In the case of Au on N-doped MgO(001) we find that charge redistribution between the metal atom and impurity takes place even when not in direct contact, which enhances the interaction of Au with CO. The presented results suggest possible ways for optimizing the reactivity of oxide supported metal catalysts through impurity engineering.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2018
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-352729 (URN)10.1039/c7cp08370j (DOI)000429280100034 ()29435542 (PubMedID)
Funder
Swedish Research Council, 2014-5993Carl Tryggers foundation
Available from: 2018-06-07 Created: 2018-06-07 Last updated: 2018-06-07Bibliographically approved
Al-Zoubi, N., Schönecker, S., Johansson, B. & Vitos, L. (2017). Assessing the Exact Muffin-Tin Orbitals method for the Bain path of metals. Philosophical Magazine, 97(15), 1243-1264
Open this publication in new window or tab >>Assessing the Exact Muffin-Tin Orbitals method for the Bain path of metals
2017 (English)In: Philosophical Magazine, ISSN 1478-6435, E-ISSN 1478-6443, Vol. 97, no 15, p. 1243-1264Article in journal (Refereed) Published
Abstract [en]

We scrutinise the muffin-tin approximation and the screening within the framework of the Exact Muffin-Tin Orbitals method in the case of cubic and tetragonal crystal symmetries. Systematic total energy calculations are carried out for the Bain path including the body-centred cubic and face-centred cubic structures for a set of simple and transition metals. The present converged results in terms of potential sphere radius (S) and hard sphere radius (b) are in good agreement with previous theoretical calculations. We demonstrate that for all structures considered here, potential sphere radii around and slightly larger than the average Wigner-Seitz radius (w) yield accurate total energy results whereas S values smaller than w give large errors. It is shown that for converged total energies hard spheres with radii b = 0.7-0.8w should be used for an efficient screening within real space clusters consisting typically of 70-90 lattice sites. The less efficient convergence of the total energy in the case of small hard spheres is ascribed to the delocalisation of the screened spherical waves, which leads to inaccurate interstitial overlap matrix. The above conclusions are not significantly affected by the volume of the system.

Place, publisher, year, edition, pages
TAYLOR & FRANCIS LTD, 2017
Keywords
The Bain path, Transition metals, The Exact Muffin-Tin Orbital (EMTO) method
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-322885 (URN)10.1080/14786435.2017.1293862 (DOI)000399958500005 ()
Funder
Swedish Research CouncilSwedish Foundation for Strategic Research The Swedish Foundation for International Cooperation in Research and Higher Education (STINT)Carl Tryggers foundation
Available from: 2017-05-31 Created: 2017-05-31 Last updated: 2017-05-31Bibliographically approved
Li, X., Schönecker, S., Zhao, J., Vitos, L. & Johansson, B. (2017). Elastic anharmonicity of bcc Fe and Fe-based random alloys from first-principles calculations. Physical Review B, 95(2), Article ID 024203.
Open this publication in new window or tab >>Elastic anharmonicity of bcc Fe and Fe-based random alloys from first-principles calculations
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2017 (English)In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 95, no 2, article id 024203Article in journal (Refereed) Published
Abstract [en]

We systematically investigate elastic anharmonic behavior in ferromagnetic body-centered cubic (bcc) Fe and Fe1-xMx (M = Al, V, Cr, Co, or Ni) random alloys by means of density-functional simulations. To benchmark computational accuracy, three ab initio codes are used to obtain the complete set of second-and third-order elastic constants (TOECs) for bcc Fe. The TOECs of Fe1-xMx alloys are studied employing the first-principles alloy theory formulated within the exact muffin-tin orbital method in combination with the coherent-potential approximation. It is found that the alloying effects on C-111, C-112, and C-123, which are governed by normal strains only, are more pronounced than those on C-144, C-166, and C-456, which involve shear strains. Remarkably, the magnitudes of all TOECs but C-123 decrease upon alloying with Al, V, Cr, Co, or Ni. Using the computed TOECs, we study compositional effects on the pressure derivatives of the effective elastic constants (dB(ij)/dP), bulk (dK/dP), and shear moduli (dG/dP) and derive longitudinal acoustic nonlinearity parameters (beta). Our predictions show that the pressure derivatives of K and G decrease with x for all solute elements and reveal a strong correlation between the compositional trends on dK/dP and dG/dP arising from the fact that alloying predominantly altersdB(11)/dP. The sensitivity of dB(11)/dP to composition is attributed to intrinsic alloying effects as opposed to lattice parameter changes accompanying solute addition. For Fe and the considered Fe-based alloys, beta along high-symmetry directions orders as beta[111] > beta[100] > beta[110], and alloying increases the directional anisotropy of beta but reduces its magnitude.

National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-315812 (URN)10.1103/PhysRevB.95.024203 (DOI)000391852800001 ()
Funder
Carl Tryggers foundation Swedish Research CouncilSwedish Foundation for Strategic Research The Swedish Foundation for International Cooperation in Research and Higher Education (STINT)
Available from: 2017-02-22 Created: 2017-02-22 Last updated: 2017-11-29Bibliographically approved
Dobrota, A. S., Pasti, I. A., Mentus, S. V., Johansson, B. & Skorodumova, N. V. (2017). Functionalized graphene for sodium battery applications: the DFT insights. Electrochimica Acta, 250, 185-195
Open this publication in new window or tab >>Functionalized graphene for sodium battery applications: the DFT insights
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2017 (English)In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 250, p. 185-195Article in journal (Refereed) Published
Abstract [en]

Considering the increasing interest in the use of graphene-based materials for energy conversion and storage applications, we have performed a DFT study of Na interaction with doped graphene, both in non-oxidized and oxidized forms. Oxidation seems to play the crucial role when it comes to the interaction of doped graphene materials with sodium. The dopants act as attractors of OH groups, making the material prone to oxidation, and therefore altering its affinity towards Na. In some cases, this can result in hydroxide or water formation - an irreversible change lethal for battery performance. Our results suggest that one should carefully control the oxidation level of doped graphene-based materials if they are to be used as sodium battery electrode materials as the optimal oxidation level depends on the dopant type.

Keywords
Graphene, Doping, Oxidation, Sodium storage, Energy conversion, Reactivity
National Category
Materials Engineering
Identifiers
urn:nbn:se:uu:diva-336302 (URN)10.1016/j.electacta.2017.07.186 (DOI)000410679300023 ()
Available from: 2018-01-23 Created: 2018-01-23 Last updated: 2018-01-23Bibliographically approved
Fu, J., Li, X., Johansson, B. & Zhao, J. (2017). Improved Finnis-Sinclair potential for vanadium-rich V-Ti-Cr ternary alloys. Journal of Alloys and Compounds, 705, 369-375
Open this publication in new window or tab >>Improved Finnis-Sinclair potential for vanadium-rich V-Ti-Cr ternary alloys
2017 (English)In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 705, p. 369-375Article in journal (Refereed) Published
Abstract [en]

We have developed an improved Finnis-Sinclair (IFS) potential for vanadium-rich V-Ti-Cr random alloys with body-centred cubic structure. An extra exponential term is added to the original FS potential to enhance the repulsive interaction. The IFS potential is fitted to experimental crystal structure, cohesive energy and elastic constants of pure metals (V, Ti and Cr) and theoretical data of binary alloys (V15Ti, V15Cr and Ti8Cr8). The good agreement of the predicted formation energies of mono-vacancy and selfinterstitial of octahedral interstitial site, tetrahedral interstitial site, < 111>-dumbbell, < 110>-dumbbell, and < 100>-dumbbell with available experimental and theoretical data confirms the validity of our IFS potential in pure V. Furthermore, the agreement of elastic properties and defect properties of typical alloy (V-4-Ti-4-Cr) with experimental or DFT data also support the applicability of the IFS potential in Vrich ternary V-Ti-Cr alloys. Finally, this work also provides a reference to develop empirical potentials for other ternary alloys.

Keywords
Finnis-Sinclair potential, V-Ti-Cr alloy, Defect properties, Mechanical properties
National Category
Metallurgy and Metallic Materials Materials Engineering
Identifiers
urn:nbn:se:uu:diva-321166 (URN)10.1016/j.jallcom.2017.02.103 (DOI)000397994700049 ()
Funder
Carl Tryggers foundation , CTS15:241
Available from: 2017-05-15 Created: 2017-05-15 Last updated: 2017-05-15Bibliographically approved
Li, C.-M., Johansson, B. & Vitos, L. (2017). Physical mechanism of delta-delta '-epsilon phase stability in plutonium. Scientific Reports, 7, Article ID 5632.
Open this publication in new window or tab >>Physical mechanism of delta-delta '-epsilon phase stability in plutonium
2017 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 5632Article in journal (Refereed) Published
Abstract [en]

Based on first-principle calculations, we have systematically explored the nature of the elastic stability and the delta-delta'-epsilon phase transitions in pure Pu at high temperature. It is found that, both the electronphonon coupling and the spin fluctuation effects tend to decrease the tetragonal elastic constant (C') of delta-Pu, accounting for its anomalous softening at high temperature. The lattice thermal expansion together with the electron-phonon coupling can stiffen C' of epsilon-Pu, promoting its mechanical stability at high temperature. The delta-epsilon transition is calculated to take place around 750-800 K, and is dominated by the phonon vibration. The delta' intermediate phase is realized around 750 K mainly because of the thermal spin fluctuation.

Place, publisher, year, edition, pages
NATURE PUBLISHING GROUP, 2017
National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-331235 (URN)10.1038/s41598-017-06009-1 (DOI)000405677200017 ()28717177 (PubMedID)
Funder
Swedish Research CouncilSwedish Foundation for Strategic Research The Swedish Foundation for International Cooperation in Research and Higher Education (STINT)
Available from: 2017-10-16 Created: 2017-10-16 Last updated: 2017-10-16Bibliographically approved
Li, X., Schonecker, S., Li, R., Li, X., Wang, Y., Zhao, J., . . . Vitos, L. (2016). Ab initio calculations of mechanical properties of bcc W-Re-Os random alloys: effects of transmutation of W. Journal of Physics: Condensed Matter, 28(29), Article ID 295501.
Open this publication in new window or tab >>Ab initio calculations of mechanical properties of bcc W-Re-Os random alloys: effects of transmutation of W
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2016 (English)In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 28, no 29, article id 295501Article in journal (Refereed) Published
Abstract [en]

To examine the effect of neutron transmutation on tungsten as the first wall material of fusion reactors, the elastic properties of W1-x-yRexOsy (0 <= x, y <= 6%) random alloys in body centered cubic (bcc) structure are investigated systematically using the all-electron exact muffin-tin orbitals (EMTO) method in combination with the coherent-potential approximation (CPA). The calculated lattice constant and elastic properties of pure W are consistent with available experiments. Both Os and Re additions reduce the lattice constant and increase the bulk modulus of W, with Os having the stronger effect. The polycrystalline shear modulus, Young's modulus and the Debye temperature increase (decrease) with the addition of Re (Os). Except for C-11, the other elastic parameters including C-12, C-44, Cauchy pressure, Poisson ratio, B/G, increase as a function of Re and Os concentration. The variations of the latter three parameters and the trend in the ratio of cleavage energy to shear modulus for the most dominant slip system indicate that the ductility of the alloy enhances with increasing Re and Os content. The calculated elastic anisotropy of bcc W slightly increases with the concentration of both alloying elements. The estimated melting temperatures of the W-Re-Os alloy suggest that Re or Os addition will reduce the melting temperature of pure W solid. The classical Labusch-Nabarro model for solid-solution hardening predicts larger strengthening effects in W1-yOsy than in W1-xRex. A strong correlation between C' and the fcc-bcc structural energy difference for W1-x-yRexOsy is revealed demonstrating that canonical band structure dictates the alloying effect on C'. The structural energy difference is exploited to estimate the alloying effect on the ideal tensile strength in the [0 0 1] direction.

Keywords
disordered W-Re-Os alloys, elastic properties, ductility, solid-solution hardening
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-299024 (URN)10.1088/0953-8984/28/29/295501 (DOI)000377504100007 ()
Funder
Swedish Research CouncilSwedish Foundation for Strategic Research
Available from: 2016-07-14 Created: 2016-07-13 Last updated: 2017-11-28Bibliographically approved
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