Lies My Teacher Told Me About Density Functional Theory: Seeing Through Them with the Hubbard Dimer

Most realistic calculations of moderately correlated materials begin with a ground-state density functional theory (DFT) calculation. While Kohn-Sham DFT is used in about 40,000 scientific papers each year, the fundamental underpinnings are not widely appreciated. In this chapter, we analyze the inherent characteristics of DFT in their simplest form, using the asymmetric Hubbard dimer as an illustrative model. We begin by working through the core tenets of DFT, explaining what the exact ground-state density functional yields and does not yield. Given the relative simplicity of the system, almost all properties of the exact exchange-correlation functional are readily visualized and plotted. Key concepts include the Kohn-Sham scheme, the behavior of the XC potential as correlations become very strong, the derivative discontinuity and the difference between KS gaps and true charge gaps, and how to extract optical excitations using time-dependent DFT. By the end of this text and accompanying exercises, the reader will improve their ability to both explain and visualize the concepts of DFT, as well as better understand where others may go wrong.Comment: This chapter appears in the book "Autumn School on Correlated Electrons: Simulating Correlations with Computers" (2021) prepared by Forschungszentrum J\"ulich; see http://hdl.handle.net/2128/28665 for published chapter. Updated versions correct citation

Generalized Gradient Approximation Made Thermal

Using the methodology of conditional-probability density functional theory, and several mild assumptions, we calculate the temperature-dependence of the Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA). This numerically-defined thermal GGA reduces to the local approximation in the uniform limit and PBE at zero temperature, and can be fit reasonably accurately (within 8%) assuming the temperature-dependent enhancement is independent of the gradient. This locally thermal PBE satisfies both the coordinate-scaled correlation inequality and the concavity condition, which we prove for finite temperatures. The temperature dependence differs markedly from existing thermal GGA's.Comment: 6 pages, 5 figure

Special Session 8 Introduction: Fundamentals to Applications in 2D Materials

Provides an overview of the 2015 Special Session 8 meeting as part of the 11th International Conference on Diffusion in Solids and Liquids, Munich, Germany, June 22-26, 2015

Unstable Identities: The European Court of Human Rights and the Margin of Appreciation

All legal systems work under a master narrative – the self-conception of most actors of the system itself. A master narrative is a short and simple story and it is the underlying premise upon which any legal system is based. It is a simple story because it paints the system in quick broad brushstrokes and at (most) times is oblivious to the paradoxes within it. Furthermore, a master narrative is important for legitimization purposes because the actors’ legitimacy will depend on their (perceived) conformity with the system’s master narrative. Therefore, legitimacy is self-referential; the yardsticks for a legitimate action are contained within the system’s master narrative, not outside of it. When talking about different international courts it is important to remember that they are embedded within a master narrative that is contextual and contingent and, at different points, more or less contested. This paper explores the question of what happens when the master-narrative is in a period of transition (from a state cantered to a post-national world order) and when the actors’ legitimacy, their interpretative endeavours the very fundamentals are in a state of flux. I use the margin of appreciation discussion as a focal point of describing the conflicting narratives under which the European Court of Human Rights works, narratives in which the different actors (judges, attorneys, NGO activists, government agents) and their consequences in terms of the interpretation of the European Convention on Human Rights

Return to Full Functioning after Graded Exercise Assessment and Progressive Exercise Treatment of Postconcussion Syndrome

Exercise assessment and aerobic exercise training for postconcussion syndrome (PCS) may reduce concussion-related physiological dysfunction and symptoms by restoring autonomic balance and improving cerebral blood flow autoregulation. In a descriptive pilot study of 91 patients referred to a university clinic for treatment of PCS, a subset of 63 patients were contacted by telephone for assessment of symptoms and return to full daily functioning. Those who experienced symptoms during a graded exercise treadmill test (physiologic PCS, n = 40) were compared to those who could exercise to capacity (PCS, n = 23). Both groups had been offered progressive exercise rehabilitation. Overall 41 of 57 (72%) who participated in the exercise rehabilitation program returned to full daily functioning. This included 27 of 35 (77%) from the physiologic PCS group, and 14 of 22 (64%) from the PCS group. Only 1 of the 6 patients who declined exercise rehabilitation returned to full functioning. Interpretation of these results is limited by the descriptive nature of the study, the small sample size, and the relatively few patients who declined exercise treatment. Nonetheless, exercise assessment indicates that approximately one third of those examined did not have physiologic PCS

Adult tonsillectomy : postoperative pain depends on indications

AbstractIntroductionIntense pain is one of the most important postoperative complaints after tonsillectomy. It is often described by patients as comparable to the pain that accompanies an acute tonsillitis. Although recurrent tonsillitis is the most frequent indication for surgery, many tonsillectomies are performed due to other indications and these patients may be unfamiliar with such pain.ObjectiveTo verify whether individuals with recurrent tonsillitis experience different post-tonsillectomy pain intensity than those with other indications for surgery, with no history of episodes of acute tonsillitis.MethodsA total of 61 tonsillectomies were performed under general anesthesia, using a potassium titanyl phosphate (KTP) laser (to eliminate the potential influence on the study results of forceful dissection of fibrotic tonsils in patients with history of recurrent tonsillitis) and multiple ligations of blood vessels within the tonsillar beds. The patients received 37.5mg Tramadoli hydrochloridum+325mg Paracetamol tablets for 10 days. Postoperative variables included the duration of hospital stay, postoperative hemorrhage and readmission rate. The patients reported pain intensity on consecutive days, pain duration, weight loss on postoperative day 10, character, intensity and duration of swallowing difficulties, and the need for additional doses of painkillers. Healing was also assessed. Capsular nerve fibers were histologically examined in the resected tonsils by immunostainings for general and sensory markers.ResultsIndications for the surgery were: recurrent acute tonsillitis (34 patients), no history of recurrent tonsillitis: focus tonsil (20) and intense malodour (7). Pain intensity on postoperative days 3–4 and incidence of readmissions due to dehydration were significantly higher in the group with no history of recurrent tonsillitis. No significant differences in relative densities of protein gene product (PGP) 9.5- and calcitonin gene-related peptide (CGRP)-immunoreactive nerve fibers were observed.ConclusionPatients with recurrent tonsillitis qualified for tonsillectomy reported lower pain intensity than those without recurrent tonsillitis and the pain scores were unrelated to nerve fibers density

Zespół zrostowy kręgosłupa, nadgarstka i śródstopia (rzadko rozpoznawany, nierzadko występujący)

Spondylocarpotarsal synostosis syndrome - a rarely recognised entity - is characterised by malsegmentation of the spine and carpal/tarsal fusions (1,2,5-9). The main reason for the rarity of its diagnosis is that radiographs of the hands and feet are not routinely performed in children with scoliosis and/or kyphoscoliosis, and fusion of the carpal/tarsal bones may not be evident in preschool children. We report four patients with spondylocarpotarsal synostosis syndrome; the diagnosis in three of these was not made until radiographs of the hands were performed. The amount of scoliosis was much less evident in two of these patients (sibs) than in the others

Significant Factors Related to Failed Pediatric Dental General Anesthesia Appointments at a Hospital-based Residency Program

Purpose: The purposes of this study were to: (1) evaluate the relationship between appointment failure and the factors of age, gender, race, insurance type, day of week, scheduled time of surgery, distance traveled, and weather; (2) investigate reasons for failure; and (3) explore the relationships between the factors and reasons for failure. Methods: Electronic medical records were accessed to obtain data for patients scheduled for dental care under general anesthesia from May 2012 to May 2015. Factors were analyzed for relation to appointment failure. Results: Data from 3,513 appointments for 2,874 children were analyzed. Bivariate associations showed statistically significant (P<0.05) relationships between failed appointment and race, insurance type, scheduled time of surgery, distance traveled, snowfall, and temperature. Multinomial regression analysis showed the following associations between factors and the reason for failure (P<0.05): (1) decreased temperature and increased snowfall were associated with weather as reason for failure; (2) the African American population showed an association with family barriers; (3) Hispanic families were less likely to give advanced notice; and (4) the "additional races" category showed an association with fasting violation. Conclusion: Patients who have treatment under general anesthesia face specific barriers to care