Posts in category Publications

Single-atom alloy Perspective made it onto the JPCL cover!

The jpcl-cover-20sep2018next issue of The Journal of Physical Chemistry Letters will feature cover art from the perspective article ‘Lonely Atoms with Special Gifts: Breaking Linear Scaling Relationships in Heterogeneous Catalysis with Single-Atom Alloys’ by Matthew T. Darby, Michail Stamatakis, Angelos Michaelides, and E. Charles H. Sykes. The cover depicts the atomic structure of a so-called single-atom alloy, which is bimetallic alloy with a low concentration of the catalytically active component. One of these active sites prominently features a methane molecule after C-H bond activation. Dispersing the active component offers potential for well-defined and enhanced catalytic performance.

View the full cover page here. The article itself can be found here (or on our publications site).

Two Open Positions for Postdocs as part of the HeteroIce Project

The ICE group currently have two open positions for postdoctoral researchers. The positions are part of the ERC HeteroIce project aimed at understanding ice nucleation. Click here to apply or find out more information.

Andrea’s and Gerit’s paper published in the PNAS

Andrea’s and Gerit’s paper has been published in the Proceedings of the National Academy of Sciences of the United States of America. The work had important contributions also from Jiří, a previous member of the ICE group, and from Dario and Alexandre, longstanding Angelos’ collaborators.

In the paper we study molecular crystals with quantum Monte Carlo.

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Computational approaches based on the fundamental laws of quantum mechanics are now integral to almost all materials design initiatives in academia and industry. If computational materials science is genuinely going to deliver on its promises, then an electronic structure method with consistently high accuracy is urgently needed. We show that, thanks to recent algorithmic advances and the strategy developed in our manuscript, quantum Monte Carlo yields extremely accurate predictions for the lattice energies of materials at a surprisingly modest computational cost. It is thus no longer a technique that requires a world-leading computational facility to obtain meaningful results. While we focus on molecular crystals, the significance of our findings extends to all classes of materials.

Martin’s paper published in Nature Commuications

Martin’s paper together with Gabriele, Fabio, Silvio and Angelos has been published in Nature Communications!

In this paper we investigate pre-critical fluctuations and what they can tell us about the heterogeneous nucleation event. Pre-critical fluctuations are the earliest occurrences of crystalline clusters in a supercooled liquid and thus readily probed in simulations such as molecular dynamics. We find that they can tell us which polymorph will form but they are not trivially indicative (as often assumed) of the nucleation enhancement. This also means that the commonly applied heterogeneous classical nucleation theory makes an error when comparing heterogeneous and homogeneous nucleation events where different polymorphs have formed. As a side, in this work we also find a simple recipe of avoiding stacking-disorder in hetergeneous ice nucleation during the nucleation stage.

Read the paper online or on our publications page.

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New paper accepted in Nature Chemistry

Our collaborative paper with Charlie Sykes, Michail Stamatakis and other entitled “PtCu Single Atom Alloys as a Coke Resistant Strategy for Efficient C-H Activation” has been accepted for publication at Nature Chemistry. Well done everyone!

The paper can be found online and in our publications list.

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Martin’s paper accepted in JCP!

Martin’s paper together with Laurent, Ming, Gabriele, Andrea and Angelos has been published in JCP Communications! In this work we studied wetting of water droplets on a substrate. With the help of metadynamics we have uncovered that for cutoffs that are more than commonplace in the MD community (2-3 sigma) the underlying free energy profile of wetting can exhibit metastable wetting states. Those states are not only unphysical but they can also be very hard to detect and could therefore corrupt computational results and interpretations. Our results show that a cutoff should not be treated as a fitting parameter in the development of force fields since the underlying physics can be inherently different and thus one needs to use long-range versions or very large cutoffs if one wants to be absolutely sure. Read the paper online or on our publications page.

Philipp’s and Martin’s paper published in PRB!

Philipp’s and Martin’s paper was published in Physical Review B! In this article they computed the ice nucleation ability of numerous model hydroxylated substrates with diverse OH group arrangements. For the substrates considered, they find that neither the symmetry of the OH patterns nor the similarity between a substrate and ice correlate well with the IN ability. Instead, they find that the OH density and the substrate-water interaction strength are useful descriptors of a material’s IN ability. This insight allows the rationalization of ice nucleation ability across a wide range of materials, and can aid the search and design of novel potent ice nucleators in the future. Check out the article online or on our publications page.

A collaborative work about high-pressure ice(s) has been accepted by JPCL

 

iceIVIs High-Density Amorphous Ice Simply a ‘Derailed’ State along the Ice I to Ice IV Pathway? In this paper, just accepted by The Journal of Physical Chemistry Letters, we try to answer that question by investigating a colection of high-pressure phase transitions – of ice, and ammonium fluoride as well, digging deep into the importance of the hydrogen bond network. The paper builds upon the excellent experiments of Jacob J. Shephard and Christoph G. Salzmann, topping up things with first principle simulations performed by Sanliang Ling and Ben Slater – a truly collaborative, UCL-branded work!

Boosting the accuracy and speed of quantum Monte Carlo: Andrea’s paper published in PRB

Andrea and Dario’s paper on the methodological improvement of the diffusion quantum Monte Carlo algorithm is finally published in Phys. Rev. B. In this work, involving also Sandro Sorella and Michael J. Gillan, we make the method up to one hundred times faster, by modifying only one line of the CASINO code. We also solve an outstanding issue of diffusion Monte Carlo, related to size-consistency, that was hampering its accuracy in many practical calculations.
It is now possible to study a whole variety of systems, including calculating interaction energies between molecules or between molecules and surfaces, or investigate the relative stability of different crystal polymorphs, with unprecedented accuracy and at a much lower computational cost.
The new method extends the range of the size of the systems that it is now possible to simulate, opening new avenues to the study of previously unaccessible problems in Nanotechnology and Material Sciences.

News

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INCITE grant awarded for quantum Monte Carlo project!

The proposal titled “New Frontiers for Material Modeling via Machine Learning Techniques with Quantum Monte Carlo” was awarded a 2019 Innovative and Novel Computational Impact on Theory and Experiment (INCITE) grant by the U.S. Department of Energy’s Office of Science. The project lead by Dario Alfè and in collaboration with Gábor Csányi in Cambridge involves […]

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Welcome new ICE group members!

We are happy to welcome some new people who joined the group over the last few weeks. Tai is doing a postdoc in a joint UCL – BP project. Fabian is sharing his PhD time between UCL and Imperial College. Michael already did his Master project in our group and is now continuing his work […]

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Martin finished his viva!

Congratulations to Martin, who finished his viva last week! His work focused on ice nucleation, in particular on finding descriptors that indicate good ice nucleating agents and the role of dynamical heterogeneity in homogeneous ice nucleation.

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The ICE group survived Hever!

Yesterday morning’s adverse weather conditions (to put it mildly) made the triathlon even more challenging. The swimmers had to cope with very cold water, the hilly bike track was dangerously slippery and the running track was mostly covered in mud. Undeterred, both teams completed the triathlon – soaking wet (even the ones that didn’t swim!) […]

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Single-atom alloy Perspective made it onto the JPCL cover!

The next issue of The Journal of Physical Chemistry Letters will feature cover art from the perspective article ‘Lonely Atoms with Special Gifts: Breaking Linear Scaling Relationships in Heterogeneous Catalysis with Single-Atom Alloys’ by Matthew T. Darby, Michail Stamatakis, Angelos Michaelides, and E. Charles H. Sykes. The cover depicts the atomic structure of a so-called […]

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The ICE group is Triathlon-ing for WaterAid again!

After last year’s phenomenal victory, the ICE group is participating for the second time in the Hever Castle Triathlon. This year, there will be two relay teams: Phil, Gabriele, and Angelos will compete again in the half-ironman, while Andrea, his wife Sara, and Patrick will compete over the Olympic distance. The ICE group is not only trying […]

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Open Postdoc position

A position for a Research Associate in Computational Catalysis is now open. The project about methane activation at single atom alloys involves collaboration with Dr Michail Stamatakis and Prof. Charlie Sykes. To find out more or to apply, click here.

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Welcome Sam and Piero!

The ICE group is happy to welcome Sam Azadi and Piero Gasparotto, who joined us last month. The weather appeared eager to welcome them warmly as well, and we hope their time here will be as enjoyable and successful as the first month promised it to be.

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Michael wins prize for his Final Year MSci presentation!

Michael won a prize for the Best Final Year MSci presentation in the Condensed Matter and Materials Physics (CMMP) group for his project on ice nucleation titled “Achieving Cubic Ice”. Congratulations!

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2 PhD positions available

Two PhD positions are available in the ICE group. The projects are aimed at applying and developing computer simulation approaches to better understand the formation of ice.

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Group gatherings