Andreas Hermann, Edinburgh

 

I am a Reader in the School of Physics and Astronomy at the University of Edinburgh. My research is in the field of computational materials science: using first-principles, parameter-free computing methods to predict and understand properties of materials - such as their stability, elastic, electronic, and optical attributes.


As member of the Centre for Science at Extreme Conditions, a part of my research focuses on the occurrence of new, interesting phases of various materials under conditions of extreme compression and high temperatures.

About Me

Contact

Office 2604

School of Physics and Astronomy

James Clerk Maxwell Building

Peter Guthrie Tait Road

The University of Edinburgh

Edinburgh, EH9 3FD


Phone +44 131 650 5824

Email a.hermann@ed.ac.uk

Join the group

Students interested to join the group for a PhD are always welcome. Research projects can be found on the School’s web pages, together with information on the application process.


Potential undergraduate research projects are listed on the School’s wiki page (requires login).


News


04/2020: Planetary mixtures

Icy planets’ atmospheres contain a large amount of hydrogen and helium. How do these relatively inert species interact with the moleculare ices that make up the mantle regions of these planets? Our recent study on helium-ammonia interactions, led by Jian Sun and published in Phys. Rev. X, showed that their interaction is much richter than hitherto thought, with intriguing high-temperature behaviour. See also the synopsis in APS Physics.


02/2020: Realistic materials strength calculations in ceramics

Ultra-high temperature ceramics (UHTC) are promising materials for a wide range of applications in the energy and transport sectors. In recent work led by Weiguo and Cheng Lu, now published in Phys. Chem. Chem. Phys., we performed realistic calculations on mechanical failure of a prototypical UHTC material, TaC, which resulted in very good agreement with experimental hardness results.


01/2020: Plasticity and superionicity in molecular mixtures

Elevated temperatures can induce intriguing states in compressed molecular systems. In our recent study published in J. Phys.:Cond. Mat. we explored mixtures of water and ammonia, which serve as proxies for icy planet mantle regions, across composition, pressure, and temperature, using ab initio molecular dynamics calculations.

This invited paper forms part of the Emerging Leaders 2019 collection of contributions, “bringing together the best early-career researchers from all areas of condensed matter physics”.


11/2019: Rare earth superhydrides

Superhydrides of rare earth metal hold great promise for high-temperature superconductivity. In a recent paper published in Phys. Rev. B led by Ross Howie and Eugene Gregoryanz, we studied the synthesis of praseodymium hydrides under pressure. Our DFT calculations helped determine the hydrides’ stoichiometries and electronic properties.


11/2019: Summer student prize for Grace

Grace Alster, who did a summer studentship in our group and ran molecular dynamics simulations on high-pressure molecular mixtures, won the department’s prize for “Best Student Project” - many congratulations to her! Grace’s success means this is the second time in a row that a summer student from our group won the department’s top prize, after Cara Lynch managed the same feat last year.


10/2019: A review on structure prediction for geosciences

Our understanding of the interior structure of Earth and other planets hinges on what we know about the mineral phases involved: their elastic properties, high-pressure phase transitions, melting lines, etc. Crystal structure prediction can aid in exploring these issues, and in an invited review I discuss how particle swarm optimization methods (but also other approaches) can be applied to mantle and core regions of rocky and icy planets.


09/2019: Special issue in Crystals on first-principles predictions

I very much enjoyed co-editing a special issue in the journal Crystals on “First-principles prediction of structures and properties in crystals”, together with Dr Dominik Kurzydłowski. I think a good set of papers was published within the special issue - have a look, it’s open access after all, and you can even order a hard copy of the entire issue in book form.




09/2019: A versatile water network for gas storage

The water network sX (“S-chi”) once more proves its versatility as host of various gases. Originally formed as part of hydrogen hydrate C0, the sX network can be emptied of the hydrogen guests and then re-filled. In the most recent case, led by Bernhard Massani and John Loveday’s experiments, this leads to a new nitrogen hydrate, as described in J. Chem. Phys. Our DFT calculations agree that the sX-N2 hydrate (NH-V) should form at moderate pressures.


05/2019: Hydrocarbons under pressure

The chemical response of hydrocarbons to compression is extraordinarily complex. In a wide-ranging computational survey of all known (and some new) hydrocarbon phases, Lewis Conway has put together the most complete phase diagram of hydrocarbons as function of composition, pressure, and temperature. The paper has been published in Geosciences. As corollary, we find the most hydrogen-rich hydrocarbon phase, with 20 wt-% releasable hydrogen stored in a methane matrix!


05/2019: Hydrogen mixes with ammonia

Compressed mixtures of small molecules make up the mantles of icy planets. Our computational survey investigating hydrogen-ammonia mixtures, coordinated by Quan Li, has appeared in Journal of Physical Chemistry Letters. From crystal structure prediction to electronic topology analyses, we show that (NH3)(H2)2 can be stabilized at relatively low pressure and benefits from unusual N-H⁃⁃⁃H- hydrogen bonding. See report on ChemistryWorld.


04/2019: Chain melting in PNAS and in the news

Nice work headlined by Victor Naden Robinson and Hongxiang Zong appeared in Proceedings of the National Academy of Sciences, on verifying the thermodynamic stability of the “chain melted” state found in compressed and heated potassium. The consequence is a state of matter that is part solid and part liquid on the atomic scale. Our paper is accompanied by a commentary in PNAS. For accessible main stream media reports of this work, see e.g. National Geographic, CNN, Scientific American, Phys.org, or the very concise version on Stephen Colbert’s Late Show.


03/2019: Synthesis of metastable phases through dynamic compression and release

Upon release from shock compression, the metal bismuth can form a metastable phase (the tetragonal beta-Sn structure) that is not seen in equilibrium conditions. Our experimentally driven paper, headlined by Martin Gorman, appeared in Applied Physics Letters and was selected as Editor’s Pick by the publisher.


02/2019: Coinage metal nitride under pressure

Our report on the first pressure- (and temperature-) induced reaction of the coinage metal copper with nitrogen, appeared in J. Phys. Chem. Lett. Jack Binns headlined the work and our calculations helped identify the structure of the newly synthesised copper diazenide compound.


12/2018: Novel ammonia-water phases under pressure

A large body of work, from structure searching to topological analyses, went into our study on the ammonia-water system under pressure, as just published in J. Chem. Phys. Victor Naden Robinson chiefly produced the results, which suggest ammonia-rich compounds should be more stable at high-pressure conditions than others.