Scientists from IFW Dresden teamed up with colleagues from over 30 universities and institutes to investigate to what extent quantum simulations of material properties agree when they are performed with different software, independently coded. Thanks to an online collaboration, they successfully demonstrated that the most recent generations of codes agree well, in contrast to earlier generations. Their study has been published in Science (issue published 25 March 2016).
Reproducibility does not come easily
It's a corner stone of science: independent yet identical experiments should produce the same results. Only in this way can science identify ‘laws’, which lead to new insight and sometimes to new technologies. However, several recent studies have pointed out that such reproducibility does not always come spontaneously.
In scientific areas as diverse as psychology research and genetic research, cases were identified where repeating previous experiments led to very different results. Even predictions by computer codes require caution, since the way in which theoretical models are implemented may affect simulation results. This is a reason for concern in any field of research that critically depends on computer simulations.
For the study and design of materials, for instance, there are several independently coded software packages available based on quantum physics. They are moreover being used increasingly often in automated procedures with limited human supervision. It is therefore essential to know to what extent predicted materials properties depend on the code that has been used.
Online collaboration brings experts together
Despite the need for reliable property predictions of materials, the reproducibility of quantum simulations had not been investigated systematically before. This is mainly because there is no single person sufficiently skilled in all existing codes. Scientists from IFW Dresden therefore joined forces with more than 60 colleagues, bringing together the know-how of over 30 prominent institutions.
The researchers investigated 40 different methods to describe the influence of pressure in 71 different crystals. Due to the highly international composition of the team, discussions and collaboration were mainly conducted via online tools – similarly to the way people collaborate to write Wikipedia.
The team can now demonstrate that, although a few of the older methods clearly yield deviating results, predictions by recent codes are equivalent. This includes a method with about 600,000 lines of code developed at IFW Dresden (http://www.fplo.de/).
Moreover, the authors define a quality criterion that allows the verification of future software developments against their extensive database. New test data are continuously added to a publicly available website (http://molmod.ugent.be/DeltaCodesDFT). The researchers involved hope that their work will contribute to higher standards for materials property simulations, and that it will facilitate the development of improved simulation codes and methods.
Dr. Manuel Richter
Institute for Theoretical Solid State Physics at IFW Dresden
Dr. Carola Langer | idw - Informationsdienst Wissenschaft
In borophene, boundaries are no barrier
17.07.2018 | Rice University
Research finds new molecular structures in boron-based nanoclusters
13.07.2018 | Brown University
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
17.07.2018 | Information Technology
17.07.2018 | Materials Sciences
17.07.2018 | Power and Electrical Engineering