Nanoscale Smoothing and the Analysis of Interfacial Charge and Dipolar Densities

The interface properties of interest in multilayers include interfacial charge densities, dipole densities, band offsets, and screening-lengths, among others. Most such properties are inaccesible to direct measurements, but are key to understanding the physics of the multilayers. They are contained within first-principles electronic structure computations but are buried within the vast amount of quantitative information those computations generate. Thus far, they have been extracted from the numerical data by heuristic nanosmoothing procedures which do not necessarily provide results independent of the smoothing process. In the present paper we develop the theory of nanosmoothing, establishing procedures for both unpolarized and polarized systems which yield interfacial charge and dipole densities and band offsets invariant to the details of the smoothing procedures when the criteria we have established are met. We show also that dipolar charge densities, i. e. the densities of charge transferred across the interface, and screening lengths are not invariant. We illustrate our procedure with a toy model in which real, transversely averaged charge densities are replaced by sums of Gaussians.Comment: 30 pages, 15 figures, 4 table

Towards a first principles description of phonons in Ni50_{50}Pt50_{50} disordered alloys: the role of relaxation

Using a combination of density-functional perturbation theory and the itinerant coherent potential approximation, we study the effects of atomic relaxation on the inelastic incoherent neutron scattering cross sections of disordered Ni$_{50}$Pt$_{50}$ alloys. We build on previous work, where empirical force constants were adjusted {\it ad hoc} to agree with experiment. After first relaxing all structural parameters within the local-density approximation for ordered NiPt compounds, density-functional perturbation theory is then used to compute phonon spectra, densities of states, and the force constants. The resulting nearest-neighbor force constants are first compared to those of other ordered structures of different stoichiometry, and then used to generate the inelastic scattering cross sections within the itinerant coherent potential approximation. We find that structural relaxation substantially affects the computed force constants and resulting inelastic cross sections, and that the effect is much more pronounced in random alloys than in ordered alloys.Comment: 8 pages, 3 eps figures, uses revtex

N-representability and stationarity in time-dependent density functional theory

To construct an N-representable time-dependent density-functional theory, a generalization to the time domain of the Levy-Lieb (LL) constrained search algorithm is required. That the action is only stationary in the Dirac-Frenkel variational principle eliminates the possibility of basing the search on the action itself. Instead, we use the norm of the partial functional derivative of the action in the Hilbert space of the wave functions in place of the energy of the LL search. The electron densities entering the formalism are $N$-representable, and the resulting universal action functional has a unique stationary point in the density at that corresponding to the solution of the Schr\"{o}dinger equation. The original Runge-Gross (RG) formulation is subsumed within the new formalism. Concerns in the literature about the meaning of the functional derivatives and the internal consistency of the RG formulation are allayed by clarifying the nature of the functional derivatives entering the formalism.Comment: 9 pages, 0 figures, Phys. Rev. A accepted. Introduction was expanded, subsections reorganized, appendix and new references adde

Local Isoelectronic Reactivity of Solid Surfaces

The quantity w^N(r) = ( 1/ k^2 T_el)[partial n(r, T_el) / partial T_el]_(v(r),N) is introduced as a convenient measure of the local isoelectronic reactivity of surfaces. It characterizes the local polarizability of the surface and it can be calculated easily. The quantity w^N(r) supplements the charge transfer reactivity measured e.g. by the local softness to which it is closely related. We demonstrate the applicability and virtues of the function w^N(r) for the example of hydrogen dissociation and adsorption on Pd(100).Comment: RevTeX, 13 pages, 3 figures, to appear in Phys. Rev. Let

Evaluation of A Biological Agent For Controlling Basidiomycete Attack of Douglas-fir and Southern Pine

A biological control agent (Binab®) containing Trichoderma polysporum and T. harzianum was evaluated for its ability to prevent or arrest attack of loblolly pine (Pinus taeda) sapwood and Douglas-fir (Pseudotsuga menziesii) heartwood by five Basidiomycetes commonly isolated from poles in service. Studies of Lentinus lepideus were included for comparison. In general, the biocontrol agents performed well against L. lepideus and other brown-rot fungi out of ground contact, but they did not completely eliminate most of the test fungi. The biological control agents had little effect on L. lepideus when the wood was exposed to soil. In addition, the biocontrol agents had little effect on white-rot fungi, which are an important component of the microflora in decaying poles. Results suggest that Binab® is not suitable for remedial decay control without supplemental treatments that favor growth and activity of Trichoderma

Phonons in random alloys: the itinerant coherent-potential approximation

We present the itinerant coherent-potential approximation(ICPA), an analytic, translationally invariant and tractable form of augmented-space-based, multiple-scattering theory in a single-site approximation for harmonic phonons in realistic random binary alloys with mass and force-constant disorder. We provide expressions for quantities needed for comparison with experimental structure factors such as partial and average spectral functions and derive the sum rules associated with them. Numerical results are presented for Ni_{55} Pd_{45} and Ni_{50} Pt_{50} alloys which serve as test cases, the former for weak force-constant disorder and the latter for strong. We present results on dispersion curves and disorder-induced widths. Direct comparisons with the single-site coherent potential approximation(CPA) and experiment are made which provide insight into the physics of force-constant changes in random alloys. The CPA accounts well for the weak force-constant disorder case but fails for strong force-constant disorder where the ICPA succeeds.Comment: 19 pages, 12 eps figures, uses RevTex

Parents\u27 Goals For ADHD Care In a Clinical Pediatric Sample

Objective. This report describes goals parents have for their children with attention deficit/hyperactivity disorder (ADHD) when coming for a pediatric visit. Method. Data were collected from 441 parents of children presenting to either a primary care pediatric practice or a developmental behavioral pediatric practice. Parents were asked to report their top 1 or 2 goals for improvement for their children, and responses were coded into 17 categories. These categories were further grouped into 7 goal composites and examined in relation to demographic characteristics of the families, office type, and symptomology. Results. Goals related to reducing symptoms of inattention were most common, but goals were heterogeneous in nature. Goals were meaningfully, but modestly, related to symptomology. In several instances, symptoms of comorbid conditions interacted with symptoms of ADHD in relation to specific goals being reported. Conclusions. Parents’ goals extended beyond ADHD symptoms. Pediatricians need an array of resources to address parents’ goals

Growing up with juvenile vulvar lichen sclerosus, the experiences and care needs of adult women with lichen sclerosus since childhood:A qualitative exploration

BackgroundVulvar lichen sclerosus (VLS) is a chronic remitting condition that affects the genital skin of females of all ages. Although qualitative studies have been conducted that have focused on women with VLS in mid-life or beyond, less is known about the experiences of individuals with VLS from childhood or adolescence onward.Objectives To gain an understanding of the experiences of women with a history of juvenile VLS (JVLS) with regard to the impact of the disease on their personal lives, and their experiences and needs regarding care and guidance.Methods A qualitative study was conducted consisting of 27 in-depth face-to-face interviews with adult women with a histologically confirmed history of JVLS, striving for maximum variation and saturation. Interviews were audio recorded and transcribed verbatim. A thorough thematic content analysis was performed.Results Three main themes were identified. Theme 1 was named 'Varying impact of living with JVLS': women experienced diverse emotional and physical impacts, from shame and denial to complete acceptance, from restrictions in daily functioning to no limitations; they felt hindered by their own lack of knowledge about JVLS and generally expressed positivity in sharing their experiences with people close to them. Theme 2 was entitled 'Finding one's way in care and guidance': while navigating care and guidance, women often felt hindered by knowledge gaps among healthcare professionals (HCPs), lack of continuity in care and guidance, lack of life phase-adjusted and future-oriented information provision, inadequate guidance around life events and insufficient monitoring of determinants of treatment adherence. Theme 3 was named 'Need for patient-tailored care involving appropriate and compassionate care and guidance': patients stressed the need for age-appropriate and life phase-adjusted information, guidance around life events and compassionate contact with knowledgeable HCPs aware of the determinants of treatment adherence and influencing factors.Conclusions Age-appropriate, life phase-adjusted, individually tailored care for women diagnosed with VLS in childhood or adolescence is needed. Care and guidance from childhood onward should encompass a standard of care adapted to the individual as their needs change over time. This involves taking interpersonal differences into account, including differences in support network and coping strategies. These findings demonstrate the need to improve awareness and knowledge about JVLS/VLS among HCPs, especially primary care providers, and among the general public