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The double sign anomaly in hydrogenated amorphous silicon, observed by LeComber et.al. [1] in 1977, has remained puzzling ever since. Recently we attacked this problem from two different directions using the equation-of-motion method. Calculations reproduce the double sign anomaly and were rationalised in terms of the behaviour of the spectral function. In a new type of calculation the motion of a
The equation-of-motion method offers advantages in the calculation of properties of large structural models, of the kind recently developed for a-Si (104 or more atoms). Originally developed for calculating densities of states, it has been shown to be adaptable to a wide variety of other purposes, including the study of localization, conductivity and the Hall effect. Recently we have shown how it
We review the problem posed by the calculation of the optical constants of solids and the adaptation of the equation-of-motion method for this purpose. In the past crystalline materials were studied by employing Bloch's theorem, but for amorphous materials and surfaces symmetry cannot generally be used to reduce the computation to manageable proportions. The equation-of-motion method avoids the ne
A new method is presented for calculating optical properties within the framework of the self-consistent linear muffin-tin orbital (LMTO) band-structure theory. We show how Green's second identity along with the commutation relation between the position and Hamiltonian operators may be used to calculate, independently of the gauge, the velocity matrix elements required for optical properties. The
Recent density-functional studies of the structural and electronic properties of a wide range of transition-metal sulphides (Raybaud P, Kresse G, Hafner J and Toulhoat H 1997 J. Phys.: Condens. Matter 9 11085, 11 107) are extended to consider the effect of magnetic ordering in sulphides formed by 3d transition metals. We find that CrS is well described as an itinerant antiferromagnet and that the
A recently developed fully unconstrained approach to non-collinear magnetism has been applied to the investigation of the magnetic ground state of triangular free-standing Cr and Mn monolayers and overlayers on Cu(111) substrates. Such systems represent a physical realization of a frustrated two-dimensional antiferromagnet. We find that the ground state of the Cr monolayers is non-collinear; it sh
The crystalline and magnetic structures of all known polymorphs of Mn have been investigated using generalized spin-density functional theory based on an unconstrained vector-field description of the magnetization density. We find that at atomic volumes smaller than 12 Å3, the magnetic ground state of α-Mn is collinear with magnetic moments ranging between 0 and 3 µB depending on the local symmetr
A maximum likelihood methodology for a general class of models is presented, using an approximate Bayesian computation (ABC) approach. The typical target of ABC methods are models with intractable likelihoods, and we combine an ABC-MCMC sampler with so-called "data cloning" for maximum likelihood estimation. Accuracy of ABC methods relies on the use of a small threshold value for comparing simulat
Several authors have reported problems on service courses in basic probability and statistics: students may lack motivation, find the theory difficult or boring, others see no applications for the results. To remedy these problems we have developed a learning environment where two important components are applied problems and use of technology. However, the mere existence of applied problems and t
Rapporten avser att ge generella riktlinjer och exempel på hur fuktsäkra takkonstruktioner i trä kan byggas. En rad viktiga faktorer som påverkar fuktsäkerheten och risken för fukt- och mögelrelaterade skador presenteras. Rapporten avser även att fungera som ett verktyg och stöd för svenska trähustillverkare, statliga och kommunala tjänstemän som handlägger byggrelaterade ärenden samt byggherrar o
Activated sludge not containing significant numbers of denitrifying, polyphosphate [poly(P)]-accumulating bacteria was grown in a fill-and-draw system and exposed to alternating anaerobic and aerobic periods. During the aerobic period, poly(P) accumulated up to 100 mg of P · g of (dry) weight. When portions of the sludge were incubated anaerobically in the presence of acetate, 80 to 90% of the int
In acetate-limited chemostat cultures of Acinetobacter johnsonii 210A at a dilution rate of 0.1 h−1 the polyphosphate content of the cells increased from 13% to 24% of the biomass dry weight by glucose (100 mM), which was only oxidized to gluconic acid. At this dilution rate, only about 17% of the energy from glucose oxidation was calculated to be used for polyphosphate synthesis, the remaining 83
The formation process of binary clusters has been studied using synchrotron based core level photoelectron spectroscopy. Free neutral krypton clusters have been produced by adiabatic expansion and doped with chloromethane molecules using the pickup technique. The comparison between the integrated intensities, linewidths, and level shifts of the cluster features of pure krypton and of chloromethane
The main purpose of this Thesis is the experimental characterization of the electronic and geometric structures of objects called clusters. A cluster consists of a finite group of bound atoms or molecules. Due to its finite size, it may present completely different properties than those of the isolated atom and the bulk. The clusters studied in this work are constituted by rare-gas atoms, organic
Healthcare databases are unique tools in public health research to evaluate the healthcareperformance and treatment compliance. Knowledge about the data quality is required toenable interpreting the results from statistical analyses. We summarize different samplingmethods suitable for the validation of healthcare databases and discuss their advantages anddisadvantages.You will learn from the prese
