Scientists have solved a decades-old puzzle about a widely used metal, thanks to extreme pressure experiments and powerful supercomputing.
Their discovery reveals important fundamental aspects of the element lithium, the lightest and simplest metal in the periodic table. The material is commonly used in batteries for phones and computers.
A mystery of how the metal’s atoms are arranged – which influences properties such as its strength, malleability and conductivity – has been solved by their research. An international team sought to better understand lithium’s structure by studying it at cold temperatures. In this low-energy state, the fundamental properties of materials can be accurately observed.
Until now, it was difficult for scientists to explain previous experimental results indicating that lithium had a complex structure. To understand the theory properly required exceptionally accurate calculations using advanced quantum mechanics. Their latest calculations, using the ARCHER supercomputer at the University of Edinburgh, found that lithium’s structure is not complex or disordered, as previous results had suggested. Instead, its atoms are arranged simply, like oranges in a box.
Scientists suggest that in previous experiments, rapid cooling led to misleading results. To avoid those problems, they reached low-temperature conditions by placing samples of lithium under extreme pressure – up to 4,500 times that of Earth’s atmosphere – by squeezing it between a pair of diamonds. They then cooled and depressurised the sample before examining it using a synchotron device, which uses X-ray beams to see atoms.
The study, from the Universities of Edinburgh and Utah, was published in Science.
We were able to form a true picture of cold lithium by making it using high pressures. Rather than forming a complex structure, it has the simplest arrangement that there can be in nature. Professor Graeme Ackland
Our calculations needed an accuracy of one in 10 million, and would have taken over 40 years on a normal computer. Dr Miguel Martinez-Canales.
Congratulations to Dr Flaviu Cipcigan whose PhD thesis was recognised by the Institute of Physics as a leading contribution in advancing theoretical condensed matter physics.
The annual “Sam Edwards Prize”, offered by the Theory of Condensed Matter Group of the Institute of Physics, searches for the PhD thesis that contributes most strongly to the advancement of theoretical condensed matter physics. This year, University of Edinburgh student Flaviu Cipcigan received the runner-up prize. Flaviu proposed a novel method to calculate long-range intermolecular interactions between molecules and applied it to create a predictive model for the water molecule.
The prize is highly competitive, with entry open to all students from the UK and Ireland whose PhD exam took place between January 2016 and April 2017. Flaviu believes he gained an edge through strong collaboration between universities, industry and governmental labs. His PhD was part of the Scottish Doctoral Training Centre in Condensed Matter Physics, with supervision from both IBM Research and the National Physical Laboratory.
I am honoured for my thesis to be recognised as one of the top theses in the UK contributing to the advancement of theoretical condensed matter physics. It is a delight to continue a research tradition of using path integral methods in complex systems, of which Sam Edwards was one of the pioneers. This award motivates me to continue performing research of the same quality and impact. Flaviu Cipcigan
Coulomb and van der Waals forces determine the structure of water, from its crystal, through its liquid, vapour and supercritical phases. Many molecular models of water have replicated these forces using empirical functions with fixed parameters. Yet, these models do not generate realistic structures. The interaction between real water molecules is modified by the environment and thus changes character at each thermodynamic state point. A full treatment of the electronic structure is not possible, as it is beyond the capability of density functional theory and beyond the speed of accurate coupled cluster methods. Electronic structure can nonetheless be captured in an efficient yet realistic way by replacing the electrons with a simpler system: a quantum harmonic oscillator, beloved by physics undergraduates across the world. This is the core idea of electronic coarse graining, the focus of Flaviu’s thesis. Using this simple yet rich method, Flaviu created a model of water transferrable between different ice, liquid, supercooled and supercritical phases in a way that previous molecular force models are not.
Congratulations to our students who received Medals, Prizes and Scholarships at the School of Physics & Astronomy awards ceremony held on 3 April 2017.
The awards, presented by Head of School Professor Arthur Trew, gave recognition to students who achieved outstanding marks during the last academic year.
A total of 23 students received a Class Medal. Class Medals are awarded to the student with the best marks in each year of each degree programme.
Prizes and Scholarships were awarded to 11 Honours students during the ceremony, including Periklis Okalidis, who was awarded the Marion A S Ross Prize, Nichol Foundation Scholarship and Astrophysics Junior Honours Medal. Periklis is currently in year 4 of his MPhys Astrophysics degree.
Spectroscopy is often used to detect phase transitions in solids. The appearance or disappearance of a peak is regarded as evidence for a change in symmetry - a different crystal phase. This general assumption has been disproven in a recent paper by PhD student Ioan Magdau and supervisor Prof. Graeme Ackland.
Solids are held together by their electrons, so it is not expected that different isotope would have different crystal structures. For example, hydrogen and deuterium have very similar phase diagrams. However, in a recent paper it was shown that an isotopic mixture of hydrogen and deuterium had completely different Raman spectra from the pure elements. This result is so outlandish that some people assumed the experiment was flawed: different numbers of vibrational modes are a classic signature of different crystal symmetry. However, calculations in CSEC showed a different story: the disordered masses of the nuclei meant that one of the most fundamental assumptions of solid state physics, the so-called Bloch theorem - broke down. In simple terms, instead of vibrations spreading throughout the crystal as waves, they become localised on a few molecules - and the number of modes seen depends on the ways that H and D atoms can be arranged nearby, rather than the crystal symmetry.
The paper is the first all-Edinburgh study to appear in the top physics journal Physical Review Letters this year.
Current student Grace Richards reflects on her attendance at the Conference for Undergraduate Women in Physics (CUWiP) UK in March 2017.
Hosted by the Oxford Women in Physics Society, this Conference for undergraduate women focused on their development as scientists and showcased opportunities for their education and professional futures. The conference included a series of workshops, panels, tours and presentations which enabled participants to meet, network and be inspired by successful women in physics.
Speakers included Professor Dame Jocelyn Bell Burnell, Professor Sheila Rowan and Professor Heidy Mader.
Grace, who is currently in her third year of her MPhys Physics degree, reflected:
What stood out was the determination of these women to succeed in their careers. The main lessons that I took away from this was to look for people to help and support you through your physics career, and not to lose confidence in your own abilities as a scientist.
Included in the conference were tours of facilities at the Rutherford Appleton Laboratory.
I also took a tour of RAL Space whilst visiting the Harwell campus. It was interesting to see opportunities in industry which I’d never considered.
The School of Physics and Astronomy covered the cost for Grace to travel to Oxford to attend the Conference.
Having the opportunity to ask high profile scientists about their research and for advice in succeeding in the future, whether that be in industry, science communication, teaching or research, was a valuable experience. I would highly recommend this conference to any female physics undergraduates who wish to meet other like-minded scientists.
Image gallery
The annual Institute of Physics conference in high energy and astroparticle physics features a fiercely fought for poster prize. This year’s winner is Maria Francesca Marzioni, a PhD student from the Edinburgh Particle Physics Experiment group.
Dark matter is the mysterious invisible substance known to make up around 85% of the mass of our Galaxy. Its fundamental particle nature remains unknown. One of the leading candidates is the axion, a particle that was originally postulated to solve the so-called strong CP problem, which asks why strong charge-parity violation, expected in the Standard Model, has not been seen in Nature. (The name axion, which is also the name of a washing powder, was chosen as the proposed mechanism ‘cleaned up’ this problem). Using data from the Large Underground Xenon (LUX) experiment, a major international experiment situated a mile underground in South Dakota, USA, Maria Francesca has now set the most sensitive constraints ever achieved for certain types of axion. She has also determined the sensitivity reach of the future LUX-ZEPLIN instrument, presently being built to replace LUX.
Maria Francesca said "It’s really exciting to work in this challenging field. To win a prize is just wonderful."
Prof Alex Murphy, Maria Francesca’s supervisor, said “I’m delighted that Maria Francesca has won this award. She has worked very hard and produced an absolutely excellent result that fully deserves such recognition.”
STFC funds for a new Centre for Doctoral Training (CDT) in Data Intensive Science have been awarded to a joint bid from University of Edinburgh, University of Glasgow & University of St Andrews. Fully funded studentships for Home/EU students are available to start in September 2017; applications open now.
We are creating a new Centre for Doctoral Training (CDT) in Data Intensive Science, pushing forward key areas of Astronomy, Particle Physics, Solar Physics and Nuclear Physics, while contributing to the creation of a new generation of data scientists. This is based on our long-standing strengths in the core science areas; our track record of innovation and leadership in applying and advancing data science technologies; and our proven record in running other physics CDTs, as well as an established geographically distributed shared Graduate School.
The key feature of the programme are:
- Four PhD year programme with integrated training.
- 6 month industrial / commercial placement.
- Fully funded 48 months studentships available to suitably qualified candidates to cover stipend and fee at Home/EU rate.
"In Edinburgh we have long been keen on how to extract science from big datasets - especially in cosmology, and in particle physics - using innovative information technology. We are excited to be part of this new initiative", Andy Lawrence, Regius Professor of Astronomy, The University of Edinburgh .
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Understanding the vast flow of data that characterises our society calls for new methodologies and algorithms. We are excited by the opportunity of applying the knowledge developed in our disciplines to these new challenges.", Luigi Del Debbio, Professor of Particle Physics and Head of Institute for Particle and Nuclear Physics.
For enquiries and how to apply see: Enquiries
Epidemiologists have long observed that the life-time probability of cancer varies greatly among different organs from which cancers originate. A new study in Science and a Perspective article shed a new light on this problem.
According to the prevalent hypothesis, cancer occurs when alterations of the genetic material cause cells to proliferate in an uncontrolled way. These alterations arise due to “intrinsic” processes such as random errors during DNA replication, and “extrinsic” factors such as chemical mutagens and ionizing radiation. A recent Science paper attempted to estimate contributions from these different processes. Using epidemiological data from 69 countries, researchers Cristian Tomasetti, Lu Li, and Bert Vogelstein (Baltimore) found a strong correlation between the logarithm of the life-time number of cellular divisions in a given tissue and the logarithm of cancer incidence rate in the same tissue. They also combined data from cancer genome sequencing projects and epidemiological studies and showed that mutations due to replication errors account for 2/3 of all mutations found in cancer.
In the Perspective article, Martin Nowak (Harvard) and Bartlomiej Waclaw (Edinburgh) show that although these results are very interesting, there is a huge gap in our understanding what actually contributes to cancer risk.
“Given what we know about cancer biology, the correlation between the risk of getting cancer and the number of stem cell divisions is not that surprising” - says B. Waclaw – “What is more surprising is that cancer risk increases slower than linearly with the number of cell divisions”.
To find out what a theoretical relationship between cancer risk and cellular divisions should be, researchers considered a mathematical model (see the picture). The model shows that cancer risk is the product of the probabilities of cancer initiation and progression. Cells in normal tissues are often divided into “compartments” of size a few to a hundred cells. Initiation requires a single cell to become “neoplastic”: to acquire a mutation that causes the cell to produce more offspring than normal cells do. The population of this neoplastic cell must then take over the entire compartment before it can spread to surrounding tissues. This process, called “fixation”, is stochastic and sometimes neoplastic cells die out. Depending on the number of mutations required to produce the first neoplastic cell, mathematical modelling predicts a linear or faster-than-linear relationship between risk R and the number of cell divisions D, R ~ D^a, where a is larger or equal to 1. However, epidemiological data shows that the risk is a sublinear function of D, and a is approximately 0.5.
The discrepancy between the model and reality means that there must be additional factors that lower cancer initiation rate in tissues with larger number of divisions. For example, additional “checkpoints” may be present in such tissues that need to be deactivated to enable cancer progression. Tissue geometry may also play a role in reducing the initiation rate in tissues with higher proliferative potential. Researchers are now working on mathematical models that would take these factors into account.
Professor Emeritus Peter Ware Higgs, Nobel Laureate in Physics 2013, has received the Royal Commission for the 1851 Exhibition Medal for his outstanding contribution to physics. The award was made at a Presidential Dinner on Tuesday 28th March 2017 by Princess Anne, the Princess Royal, at the Armourer’s Hall in the City of London.
It is only the third time the Medal has been awarded since its introduction in 2006. The first was awarded to His Royal Highness The Duke of Edinburgh on the fortieth anniversary of his Presidency. The second was presented to Sir Alan Rudge on his retirement as Chairman after eighteen years of service to the Commission. The Commissioners were unanimous in their decision to award the third to Professor Higgs.
Professor Peter Higgs
Peter Higgs held, as a postdoctoral researcher, a Royal Commission for the 1851 Exhibition Senior Studentship from 1953 to 1955. He spent the first year at King’s College London where he worked on what would now be described as theoretical chemistry. He spent his second year of 1954-1955 at the University of Edinburgh at the Department of Natural Philosophy. He remained in Edinburgh for the subsequent year of 1955-1956 as a Senior Research Fellow. He then returned to London, spending time at Imperial College and University College, until his appointment as a Lecturer in the Tait Institute of Mathematical Physics Mathematical Physics in 1960.
Professor Higgs went on to further his studies at Edinburgh and in the 1960s, he developed the theory of the Higgs Field and Higgs Mechanism. He was elected a Fellow of the Royal Society in 1983 and a Fellow of the Institute of Physics in 1991. He retired in 1996, becoming Professor Emeritus at the University of Edinburgh. In 2013, he received the Nobel Prize in Physics, jointly with François Englert, for “the theoretical discovery of a mechanism that contributes to our understanding of the origin of mass of subatomic particles”; a discovery that was confirmed by the ATLAS and CMS experiments at CERNs Large Hadron Collider.
The Royal Commission for the 1851 Exhibition
The Commission was originally founded by Prince Albert to organise the Great Exhibition of 1851 and then use its profits to “increase the means of industrial education and extend the influence of science and art upon productive industry”. With over 6 million visitors to the exhibition there was substantial profits which were used to purchase 87 acres of land in South Kensington stretching from Kensington Gore to Cromwell Road. Here they aided the establishment of the Victoria and Albert Museum, the Science Museum, the Natural History Museum, the Royal Albert Hall and Imperial College as well as the Royal College of Art and the Royal College of Music.
The Commission has a long history of supporting scientists and engineers for research, development and design through its awards programmes, which have been running since the 1890s. It has a total annual disbursement of £2.5m a year and, in addition to Professor Higgs, the Commission has funded twelve other scientists that have gone on to receive Nobel Prizes, including Sir James Chadwick, Ernest Rutherford and Paul Dirac.
The University of Edinburgh team of physicists went on to win third place in the final gaining a prize of £250 and beating a number of business teams from universities across the UK. A real coup for the School of Physics and Astronomy the University of Edinburgh.
The IBM Universities Business Challenge (UBC) Worldwide is the world’s longest established undergraduate simulation-based competition designed to develop employability and enterprise skills.
Facilitated by Susan Bird (Careers Consultant, School of Physics and Astronomy), the School submitted two teams, one team making the semi-final in Edinburgh. After a keynote introduction from Shelagh Green, (Director, Careers Service), the teams did a series of intensive, timed business simulations culminating in a 60 second innovation pitch.
The Physics team – students Imran Marwat (team leader), Fidel Elie, Ziyi Zhang, Adamos Spanashis and Brandon Christman – not only won 2nd place at the semi-final and went on to win third place in the final - but also won Best Business Idea on the day, beating 19 other teams from other UK universities.
The School funded the team’s travel & accommodation expenses to the London final, the team was mentored by Mike Ross from Standard Life Investments & supported by the Careers Service – a good example of how we work with Schools & industry partners to support the employability and professional development of our science students.
Here’s how team member Ziyi Zhang reflected on the Challenge:
“Thank you for being at the competition and supporting us throughout this experience. I realized studying physics not only made us “book smart” but also taught us critical and logical thinking which can be applied beyond academics”
"Many congratulations to Imran, Fidel, Ziyi, Adamos and Brandon for a truly impressive result in this prestigious competition. It's a great achievement by everyone in the team and is a clear demonstration that the skills they've developed through their time at university have applicability far beyond physics and astronomy." Judy Hardy, Director of Teaching