Dynamic transverse magnetic susceptibility in the projector augmented-wave method. Application to Fe, Ni, and Co

We present a first principles implementation of the dynamic transverse magnetic susceptibility in the framework of linear response time-dependent density functional theory. The dynamic susceptibility allows one to obtain the magnon dispersion as well as magnon lifetimes for a particular material, which strongly facilitates the interpretation of inelastic neutron scattering experiments as well as other spectroscopic techniques. We apply the method to Fe, Ni, and Co and perform a thorough convergence analysis with respect the basis set size, $k$-point sampling, spectral smearing and unoccupied bands. In particular, it is shown that while the gap error (acoustic magnon energy at $\mathbf{q}=\mathbf{0}$) is highly challenging to converge, the spin-wave stiffness and the dispersion relation itself are much less sensitive to convergence parameters. Our final results agrees well with experimentally extracted magnon dispersion relations except for Ni, where it is well-known that the exchange splitting energy is poorly represented in the local density approximation. We also find good agreement with previous first principles calculations and explain how differences in the calculated dispersion relations can arise from subtle differences in computational approaches.Comment: 32 pages, 14 figure

Plane wave implementation of the magnetic force theorem for magnetic exchange constants: Application to bulk Fe, Co and Ni

We present a plane wave implementation of the magnetic force theorem, which provides a first principles framework for extracting exchange constants parameterizing a classical Heisenberg model description of magnetic materials. It is shown that the full microscopic exchange tensor may be expressed in terms of the static Kohn-Sham susceptibility tensor and the exchange-correlation magnetic field. This formulation allows one to define arbitrary magnetic sites localized to predefined spatial regions, hence rendering the problem of finding Heisenberg parameters independent of any orbital decomposition of the problem. The susceptibility is calculated in a plane wave basis, which allows for systematic convergence with respect to unoccupied bands and spatial representation. We then apply the method to the well-studied problem of calculating adiabatic spin wave spectra for bulk Fe, Co and Ni, finding good agreement with previous calculations. In particular, we utilize the freedom of defining magnetic sites to show that the calculated Heisenberg parameters are robust towards changes in the definition of magnetic sites. This demonstrates that the magnetic sites can be regarded as well defined and thus asserts the relevance of the Heisenberg model description despite the itinerant nature of the magnetic state

Strong Emergence and its Relation to Philosophy of Mind

This paper attempts to answer the question of whether strong emergence is a tenable concept and examine how it relates to philosophy of mind. Strong emergence is the idea that truths about a given high-level phenomenon are not reducible, even in principle, to the low-level phenomenon on which it depends. This article advances the position that strong emergence, though a tenable concept, cannot present any convincing and unproblematic instantiations in nature. Furthermore, strong emergence might imply counterintuitive conse-quences for causational structures and philosophy of mind.Denne artikel forsøger at besvare spørgsmålet om hvorvidt stærk emergens er et holdbart begreb, hvad det medfører, om der findes eksempler på stærk emergens og hvordan dette vedrører bevidsthedsfilosofi. Ifølge stærk emergens er visse sandheder om et givet høj-niveaus fænomen ikke reducer-bare, end ikke principielt, til det fænomen på lavere niveau som det afhænger af. I artiklen argumenteres der for at selvom stærk emergens er et holdbart begreb, så findes der ikke nogen overbevisende og uproblematiske eksempler i naturen. Ydermere medfører stærk emergens kontraintuitive konsekvenser for kausale strukturer og bevidsthedsfilosofi

European microbiologically influenced corrosion network (EURO-MIC): new paths for science, sustainability and standards

ABSTRACT: Microbiologically influenced corrosion (MIC) is the corrosion of material caused or enhanced by microorganisms. It occurs directly or indirectly through their metabolic activities and can be accelerated 10 to 100 times, depending on the material. A wide range of materials can be affected by MIC, including metal, plastic, and concrete, impacting the entire infrastructure of society, including water and wastewater management systems, marine industrial facilities, and (on)offshore systems. One challenge of MIC common to all these sectors is the colonization of surfaces, where the presence of water is one of the basic requirements for biofilm to form. This phenomenon is a major global challenge caused by the growing world population and related industrial activities combined with climate change, and increasingly becoming a problem for our society [1] and [2]. The global cost of MIC is unambiguous and should almost certainly be underestimated. According to survey data, MIC is responsible for up to 20% of all corrosion found in aqueous systems, costing billions of dollars in rehabilitation costs alone [1]. In Europe, several research groups/ other industrial stakeholders are already dealing with MIC. Unfortunately, the discussions are fragmented, and the exchange of information is limited. A true transdisciplinary approach is hardly ever experienced, although this would be logical for this material/biology related challenge. Therefore, Europe needs to combine the efforts of experts in different fields and develop prevention measures according to the european rules, in close cooperation with industry, plant operators and owners of critical infrastructure to effectively contribute to this MIC challenge. In this context, our european MIC-network aims to provide the necessary interaction and communication, knowledge sharing, training of personnel and of researchers of different disciplines. Only in this Europe can get a leading role in this process, bringing ideas together on an equal level with other nations, and thereby considering the important values and attitudes for Europe (e.g., environmental protection) and resulting in a greater protection for people, property, and the environment. The working group structure of this Euro-MIC Cost Action, as well as specific objectives, ongoing activities, and expected impacts, will be presented.info:eu-repo/semantics/publishedVersio

Unges deltagelse i vejledning: og samarbejdet herom

The article is based on an empirical study ex- amining the cooperation between career guid- ance practitioners and teachers, as well as how young people participate in the complex and conflict-ridden field of school-based career guidance. There are a number of inherent contradictions in the legislation governing teaching and career guidance in schools. These contradic- tions have an impact on the cooperation between guidance practitioners and teachers and on the participation of young people in career guidance activities. The article shows that the cooperation between different professional groups is a complex matter that is pivotal in determining how career guidance is practised and plays out within the school setting. Furthermore, the article demonstrates that young people participate in career guidance activities based on their understanding of the aim of the activities. Educational choice is a strong category in the field. The article discusses issues of social justice and how, unintentionally, career guidance and teaching can reproduce unequal conditions for different young people. Efforts to broaden the scope of what young people consider relevant and worthy educational pathways and career opportunities are examined as a crucial task for career guidance with ramifications for so- cial justice. The article concludes with a discussion of the potentials for developing career guidance provision in schools. A shift in perspective is proposed – from a view that the primary pur- pose of guidance activities is to help young people choose an educational pathway to a greater focus on the learning that participa- tion in guidance activities can support – where learning is understood as expanding the indi- vidual’s influence on the conditions of his or her own life.Artiklen er baseret på et empirisk forsk- ningsprojekt, der undersøger professionel- les samarbejde om og unges deltagelse i den sammensatte og modsætningsfyldte sag, som uddannelses- og erhvervsvejledning i skolen udgør. Der er en række indbyggede modsigelser i lovgivningen omkring undervisning og vejled- ning, som har betydning for de professionelles samarbejde og for unges deltagelse i vejled- ningen. Artiklen giver indsigt i, at samarbej- det mellem de professionelle er komplekst og centralt for den måde, vejledningen praktise- res og kan udfolde sig i samspil med skolen. Endvidere giver artiklen indsigt i, at unges forståelser af hvad vejledning skal bidrage til har betydning for deres oplevelse af mening og deres deltagelse i vejledningsaktiviteter. Uddannelsesvalg og afklarethed er stærke kategorier i feltet. Artiklen diskuterer spørgsmål omkring social retfærdighed og hvordan den sociale praksis i vejledning og undervisning ubemærket kan skabe ulige betingelser for forskellige unge. Det diskuteres, at det er centralt i vejledning og har social retfærdighedsimplikationer at arbejde for at udvide rammerne for, hvad unge oplever som relevante og anerkendelses- værdige muligheder. Afslutningsvist diskuteres potentialer for udvikling af vejledningen i samspil med skolen, og der foreslås et perspektivskifte fra, at vejledningsaktiviteter primært skal føre til valg af uddannelse til, at de skal have større fokus på den læring, som deltagelse i vejledningsaktiviteter kan bidrage til – hvor læring forstås som en udvidelse af rådighed ift. en social verden