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1.
J. bras. nefrol ; 46(3): e20230029, July-Sept. 2024. tab, graf
Article in English | LILACS-Express | LILACS | ID: biblio-1550504

ABSTRACT

ABSTRACT Introduction: Lung diseases are common in patients with end stage kidney disease (ESKD), making differential diagnosis with COVID-19 a challenge. This study describes pulmonary chest tomography (CT) findings in hospitalized ESKD patients on renal replacement therapy (RRT) with clinical suspicion of COVID-19. Methods: ESKD individuals referred to emergency department older than 18 years with clinical suspicion of COVID-19 were recruited. Epidemiological baseline clinical information was extracted from electronic health records. Pulmonary CT was classified as typical, indeterminate, atypical or negative. We then compared the CT findings of positive and negative COVID-19 patients. Results: We recruited 109 patients (62.3% COVID-19-positive) between March and December 2020, mean age 60 ± 12.5 years, 43% female. The most common etiology of ESKD was diabetes. Median time on dialysis was 36 months, interquartile range = 12-84. The most common pulmonary lesion on CT was ground glass opacities. Typical CT pattern was more common in COVID-19 patients (40 (61%) vs 0 (0%) in non-COVID-19 patients, p < 0.001). Sensitivity was 60.61% (40/66) and specificity was 100% (40/40). Positive predictive value and negative predictive value were 100% and 62.3%, respectively. Atypical CT pattern was more frequent in COVID-19-negative patients (9 (14%) vs 24 (56%) in COVID-19-positive, p < 0.001), while the indeterminate pattern was similar in both groups (13 (20%) vs 6 (14%), p = 0.606), and negative pattern was more common in COVID-19-negative patients (4 (6%) vs 12 (28%), p = 0.002). Conclusions: In hospitalized ESKD patients on RRT, atypical chest CT pattern cannot adequately rule out the diagnosis of COVID-19.


RESUMO Introdução: Doenças pulmonares são comuns em pacientes com doença renal em estágio terminal (DRET), dificultando o diagnóstico diferencial com COVID-19. Este estudo descreve achados de tomografia computadorizada de tórax (TC) em pacientes com DRET em terapia renal substitutiva (TRS) hospitalizados com suspeita de COVID-19. Métodos: Indivíduos maiores de 18 anos com DRET, encaminhados ao pronto-socorro com suspeita de COVID-19 foram incluídos. Dados clínicos e epidemiológicos foram extraídos de registros eletrônicos de saúde. A TC foi classificada como típica, indeterminada, atípica, negativa. Comparamos achados tomográficos de pacientes com COVID-19 positivos e negativos. Resultados: Recrutamos 109 pacientes (62,3% COVID-19-positivos) entre março e dezembro de 2020, idade média de 60 ± 12,5 anos, 43% mulheres. A etiologia mais comum da DRET foi diabetes. Tempo médio em diálise foi 36 meses, intervalo interquartil = 12-84. A lesão pulmonar mais comum foi opacidades em vidro fosco. O padrão típico de TC foi mais comum em pacientes com COVID-19 (40 (61%) vs. 0 (0%) em pacientes sem COVID-19, p < 0,001). Sensibilidade 60,61% (40/66), especificidade 100% (40/40). Valores preditivos positivos e negativos foram 100% e 62,3%, respectivamente. Padrão atípico de TC foi mais frequente em pacientes COVID-19-negativos (9 (14%) vs. 24 (56%) em COVID-19-positivos, p < 0,001), enquanto padrão indeterminado foi semelhante em ambos os grupos (13 (20%) vs. 6 (14%), p = 0,606), e padrão negativo foi mais comum em pacientes COVID-19-negativos (4 (6%) vs. 12 (28%), p = 0,002). Conclusões: Em pacientes com DRET em TRS hospitalizados, um padrão atípico de TC de tórax não pode excluir adequadamente o diagnóstico de COVID-19.

2.
Ann Med ; 56(1): 2365405, 2024 Dec.
Article in English | MEDLINE | ID: mdl-38902995

ABSTRACT

BACKGROUND: Atrioventricular block (AVB) is rare in hyperthyroidism (HTH). Little is known about the true prevalence, clinical course, optimal management, and outcomes of different types of AVBs in patients with HTH. To address these uncertainties, we aimed to conduct a systematic review by combining the available literature to provide more meaningful data regarding AVBs in HTH. METHODS: We systematically searched PubMed, Scopus, Embase, and Google Scholar for articles reporting patients who developed AVB in the context of HTH. Data were analysed in STATA 16. The main outcomes included types of AVB, frequency of pacemaker insertion, and resolution of AVB. The systematic review is registered with the International Prospective Register of Systematic Reviews (PROSPERO) with the identification number CRD42022335598. RESULTS: A total of 56 studies (39 case reports, 12 case series, 3 conference abstracts, 1 retrospective study, and 1 prospective observational study) with 87 patients were included in the analysis, with a mean age of 39.1 ± 17.6 years. Females constituted 65.7% (n = 48) of the cohort. Complete heart block (CHB) was the most commonly reported AVB (N = 45, 51.7%), followed by first-degree AVB (16.1%) and second-degree AVB (14.9%). Overall, 21 patients underwent pacing. A permanent pacemaker was inserted in one patient with second-degree AVB and six patients with CHB. Mortality was reported in one patient with CHB. The clinical course and management of HTH and AVBs did not differ in patients with CHB or lower-degree blocks. Apart from lower rates of goitre and more use of carbimazole in those who underwent pacing, no differences were found when compared to the patients managed without pacing. CONCLUSION: Current data suggest that CHB is the most common type of AVB in patients with HTH. Most patients can be managed with anti-thyroid management alone. Additionally, whether pacemaker insertion alters the clinical outcomes needs further exploration.


Subject(s)
Atrioventricular Block , Hyperthyroidism , Pacemaker, Artificial , Humans , Hyperthyroidism/complications , Hyperthyroidism/therapy , Atrioventricular Block/therapy , Atrioventricular Block/epidemiology , Atrioventricular Block/etiology , Female , Male , Adult , Middle Aged
3.
J Bras Nefrol ; 46(3): e20230029, 2024.
Article in English, Portuguese | MEDLINE | ID: mdl-38502952

ABSTRACT

INTRODUCTION: Lung diseases are common in patients with end stage kidney disease (ESKD), making differential diagnosis with COVID-19 a challenge. This study describes pulmonary chest tomography (CT) findings in hospitalized ESKD patients on renal replacement therapy (RRT) with clinical suspicion of COVID-19. METHODS: ESKD individuals referred to emergency department older than 18 years with clinical suspicion of COVID-19 were recruited. Epidemiological baseline clinical information was extracted from electronic health records. Pulmonary CT was classified as typical, indeterminate, atypical or negative. We then compared the CT findings of positive and negative COVID-19 patients. RESULTS: We recruited 109 patients (62.3% COVID-19-positive) between March and December 2020, mean age 60 ± 12.5 years, 43% female. The most common etiology of ESKD was diabetes. Median time on dialysis was 36 months, interquartile range = 12-84. The most common pulmonary lesion on CT was ground glass opacities. Typical CT pattern was more common in COVID-19 patients (40 (61%) vs 0 (0%) in non-COVID-19 patients, p < 0.001). Sensitivity was 60.61% (40/66) and specificity was 100% (40/40). Positive predictive value and negative predictive value were 100% and 62.3%, respectively. Atypical CT pattern was more frequent in COVID-19-negative patients (9 (14%) vs 24 (56%) in COVID-19-positive, p < 0.001), while the indeterminate pattern was similar in both groups (13 (20%) vs 6 (14%), p = 0.606), and negative pattern was more common in COVID-19-negative patients (4 (6%) vs 12 (28%), p = 0.002). CONCLUSIONS: In hospitalized ESKD patients on RRT, atypical chest CT pattern cannot adequately rule out the diagnosis of COVID-19.


Subject(s)
COVID-19 , Kidney Failure, Chronic , Humans , Female , Middle Aged , Aged , Male , SARS-CoV-2 , Renal Dialysis , Tomography, X-Ray Computed/methods , Lung/diagnostic imaging , Kidney Failure, Chronic/complications , Kidney Failure, Chronic/therapy , Retrospective Studies
4.
Adv Mater ; 36(1): e2307085, 2024 Jan.
Article in English | MEDLINE | ID: mdl-37985412

ABSTRACT

A large scale study of conventional superconducting materials using a machine-learning accelerated high-throughput workflow is performed, starting by creating a comprehensive dataset of around 7000 electron-phonon calculations performed with reasonable convergence parameters. This dataset is then used to train a robust machine learning model capable of predicting the electron-phonon and superconducting properties based on structural, compositional, and electronic ground-state properties. Using this machine, the transition temperatures (Tc ) of approximately 200 000 metallic compounds are evaluated, all of which are on the convex hull of thermodynamic stability (or close to it) to maximize the probability of synthesizability. Compounds predicted to have Tc values exceeding 5 K are further validated using density-functional perturbation theory. As a result, 541 compounds with Tc values surpassing 10 K, encompassing a variety of crystal structures and chemical compositions, are identified. This work is complemented with a detailed examination of several interesting materials, including nitrides, hydrides, and intermetallic compounds. Particularly noteworthy is LiMoN2 , which is predicted to be superconducting in the stoichiometric trigonal phase, with a Tc exceeding 38 K. LiMoN2 has previously been synthesized in this phase, further heightening its potential for practical applications.

5.
Headache ; 63(7): 872-879, 2023.
Article in English | MEDLINE | ID: mdl-37326359

ABSTRACT

OBJECTIVE: To translate, culturally adapt, and validate a version of the ID Migraine into Latin American Spanish. BACKGROUND: Although still considered a common diagnosis, half of the patients with migraine in Latin America experience diagnostic delay. The ID Migraine is a test developed in 2003 as a valuable tool for the early diagnosis of migraine at the primary care level; however, there is no validated Spanish or culturally adapted version for the Spanish-speaking population. METHODS: This is an analytical, translation, and test-validation study. We performed back translation and cross-cultural adaptation. The Latin American Spanish version ID Migraine MX was applied to headache clinic patients from March 2021 to January 2022 to perform a validation process against the gold standard: blinded expert diagnosis according to the International Classification of Headache Disorders, 3rd edition (ICHD-3), criteria. RESULTS: One hundred seventeen patients from the headache clinic of the National Institute of Neurology and Neurosurgery of Mexico City were screened. We found 62/117 (53%) patients positive for screening with ID Migraine MX, and 47/117 (40%) positive for migraine according to ICHD-3 criteria. A sensitivity (95% CI) of 0.91 (0.80-0.97), specificity of 0.73 (0.61-0.82), positive predictive value of 0.694 (0.57-0.794), and negative predictive value of 0.93 (0.83-0.97) were obtained. The positive likelihood ratio was 3.38 (2.27-4.99), and the negative likelihood ratio was 0.12 (0.04-0.30). After calling the patients 1 month after the first interview, the calculated Kappa test-retest was 0.75 (p = 0.001). CONCLUSION: A translated and cross-culturally adapted version into Spanish of the ID Migraine was obtained, with a diagnostic performance similar to the original instrument. Clinicians may use this test at the first level of care to reduce the rate of misdiagnosis and the time from onset of symptoms to diagnosis and treatment of migraine.


Subject(s)
Cross-Cultural Comparison , Migraine Disorders , Humans , Latin America , Delayed Diagnosis , Surveys and Questionnaires , Migraine Disorders/diagnosis , Migraine Disorders/epidemiology , Headache , Reproducibility of Results
6.
Adv Mater ; 35(22): e2210788, 2023 Jun.
Article in English | MEDLINE | ID: mdl-36949007

ABSTRACT

Crystal-graph attention neural networks have emerged recently as remarkable tools for the prediction of thermodynamic stability. The efficacy of their learning capabilities and their reliability is however subject to the quantity and quality of the data they are fed. Previous networks exhibit strong biases due to the inhomogeneity of the training data. Here a high-quality dataset is engineered to provide a better balance across chemical and crystal-symmetry space. Crystal-graph neural networks trained with this dataset show unprecedented generalization accuracy. Such networks are applied to perform machine-learning-assisted high-throughput searches of stable materials, spanning 1 billion candidates. In this way, the number of vertices of the global T = 0 K phase diagram is increased by 30% and find more than ≈150 000 compounds with a distance to the convex hull of stability of less than 50 meV atom-1 . The discovered materials are then accessed for applications, identifying compounds with extreme values of a few properties, such as superconductivity, superhardness, and giant gap-deformation potentials.

7.
Blood Cancer J ; 13(1): 18, 2023 01 24.
Article in English | MEDLINE | ID: mdl-36693840

ABSTRACT

Functional perturbations of the cohesin complex with subsequent changes in chromatin structure and replication are reported in a multitude of cancers including acute myeloid leukemia (AML). Mutations of its STAG2 subunit may predict unfavorable risk as recognized by the 2022 European Leukemia Net recommendations, but the underlying evidence is limited by small sample sizes and conflicting observations regarding clinical outcomes, as well as scarce information on other cohesion complex subunits. We retrospectively analyzed data from a multi-center cohort of 1615 intensively treated AML patients and identified distinct co-mutational patters for mutations of STAG2, which were associated with normal karyotypes (NK) and concomitant mutations in IDH2, RUNX1, BCOR, ASXL1, and SRSF2. Mutated RAD21 was associated with NK, mutated EZH2, KRAS, CBL, and NPM1. Patients harboring mutated STAG2 were older and presented with decreased white blood cell, bone marrow and peripheral blood blast counts. Overall, neither mutated STAG2, RAD21, SMC1A nor SMC3 displayed any significant, independent effect on clinical outcomes defined as complete remission, event-free, relapse-free or overall survival. However, we found almost complete mutual exclusivity of genetic alterations of individual cohesin subunits. This mutual exclusivity may be the basis for therapeutic strategies via synthetic lethality in cohesin mutated AML.


Subject(s)
Leukemia, Myeloid, Acute , Humans , Chromosomal Proteins, Non-Histone/genetics , Leukemia, Myeloid, Acute/diagnosis , Leukemia, Myeloid, Acute/genetics , Mutation , Prognosis , Retrospective Studies , Cohesins
9.
Front Med (Lausanne) ; 9: 904795, 2022.
Article in English | MEDLINE | ID: mdl-35755074

ABSTRACT

Background: Kidney transplantation is the best treatment option for patients with end-stage kidney disease (ESKD) with a superiority of graft survival after living kidney donation (LKD) compared to deceased donation. However, a large part of potential donors and recipients are ineligible for LKD. Here, we analyze the leading causes for disqualification of potential living donor-recipient pairs from the LKD program and the health-related consequences for ESKD patients excluded from the LKD program in a German transplant center. Methods: In this single-center retrospective cohort study we evaluated all candidates (potential donors and recipients) presenting for assessment of LKD from 2012 to 2020 at our transplant center. Thereby we focused on candidates excluded from the LKD program. Main reasons for disqualification were categorized as medical (donor-related), psychosocial, immunological, recipient-related, and unknown. Results: Overall, 601 donor-recipient pairs were referred to our transplant center for LKD assessment during the observation time. Out of those, 326 (54.2%) discontinued the program with 52 (8.7%) dropouts and 274 (45.6%) donor-recipient pairs being ineligible for LKD. Donor-related medical contraindications were the main reason for disqualification [139 out of 274 (50.7%) potential donors] followed by recipient-related contraindications [60 out of 274 (21.9%) of potential donor-recipient pairs]. Only 77 out of 257 (29.9%) potential recipients excluded from the LKD program received a kidney transplant afterward with a median waiting time of 2 (IQR: 1.0-4.0) years. Overall, 18 (7.0%) ESKD patients initially declined for LKD died in this period. Conclusion: A large percentage of donor-recipient pairs are disqualified from the German LKD program, mostly due to medical reasons related to the donor and with partly severe consequences for the potential recipients. For these, alternative solutions that promptly enable kidney transplantation are essential for improving patient quality of life and survival.

10.
Sci Data ; 9(1): 64, 2022 Mar 02.
Article in English | MEDLINE | ID: mdl-35236866

ABSTRACT

In the past decade we have witnessed the appearance of large databases of calculated material properties. These are most often obtained with the Perdew-Burke-Ernzerhof (PBE) functional of density-functional theory, a well established and reliable technique that is by now the standard in materials science. However, there have been recent theoretical developments that allow for increased accuracy in the calculations. Here, we present a dataset of calculations for 175k crystalline materials obtained with two functionals: geometry optimizations are performed with PBE for solids (PBEsol) that yields consistently better geometries than the PBE functional, and energies are obtained from PBEsol and from SCAN single-point calculations at the PBEsol geometry. Our results provide an accurate overview of the landscape of stable (and nearly stable) materials, and as such can be used for reliable predictions of novel compounds. They can also be used for training machine learning models, or even for the comparison and benchmark of PBE, PBEsol, and SCAN.

11.
Int J Med Educ ; 12: 101-124, 2021 May 28.
Article in English | MEDLINE | ID: mdl-34053914

ABSTRACT

OBJECTIVES: To describe the published literature on EBM curricula for physicians in training and barriers during curriculum implementation. METHODS: We performed a systematic search and review of the medical literature on PubMed, Embase, ERIC, Scopus and Web of Science from the earliest available date until September 4, 2019. RESULTS: We screened 9,042 references and included 29 full-text studies and 14 meeting abstracts. Eighteen studies had moderate validity, and 6 had high validity. The EBM curricular structure proved highly variable in between studies. The majority of the EBM curricula was longitudinal with different lengths. Only five studies reported using Kern's six-step approach for curriculum development. Twenty-one articles reported on EBM skills and knowledge, and only 5/29 full-text articles used a validated assessment tool. Time was the main barrier to EBM curriculum implementation. All the included studies and abstracts, independent of the EBM curriculum structure or evaluation method used, found an improvement in the residents' attitudes and/or EBM skills and knowledge. CONCLUSIONS: The current body of literature available to guide educators in EBM curriculum development is enough to constitute a strong scaffold for developing any EBM curriculum. Given the amount of time and resources needed to develop and implement an EBM curriculum, it is very important to follow the curriculum development steps and use validated assessment tools.


Subject(s)
Internship and Residency , Physicians , Attitude , Curriculum , Evidence-Based Medicine/education , Humans
12.
Clin Cardiol ; 44(5): 708-714, 2021 May.
Article in English | MEDLINE | ID: mdl-33760247

ABSTRACT

BACKGROUND: Transcatheter mitral valve repair (TMVR) has shown to improve symptoms and functional capacity in patients with severe mitral valve regurgitation (MR). Novel device developments provide the technology to treat patients with complex anatomies and large coaptation gaps. Nevertheless, the question of superiority of one device remains unanswered. We aimed to compare the MitraClip XTR and MitraClip NTR system in a real world setting. HYPOTHESIS: TMVR with the MitraClip XTR system is equally effective, but associated with a higher risk of leaflet injury. METHODS: We retrospectively analyzed peri-procedural and mid-term clinical and echocardiographic outcomes of 113 patients treated for severe MR between March 2018 and August 2019 at the University Hospital of Munich. RESULTS: Postprocedural MR reduction to ≤2+ was comparable in both groups (XTR: 96.1% vs. NTR: 97.6%, p = .38). There was a significant difference in a composite safety endpoint of periprocedural Major adverse cardiac and cerebrovascular events (MACCE) including leaflet injury between groups (XTR 14.6% vs. NTR 1.7%, 95% CI [2.7, 24.6], p = .012). After a median follow-up of 8.5 (4.4, 14.0) months, durable reduction of MR was confirmed (XTR: in 91.9% vs. NTR: 96.8%, p = .31) and clinical and symptomatic improvement was comparable in both groups accordingly. CONCLUSION: While efficacy was comparable in both treatment groups, patients treated with the MitraClip XTR systems showed more events of acute leaflet tear and single leaflet device attachment (SLDA). A detailed echocardiographic assessment should be done to identify risk candidates for acute leaflet injury.


Subject(s)
Heart Valve Prosthesis Implantation , Mitral Valve Insufficiency , Percutaneous Coronary Intervention , Aged , Cardiac Catheterization/adverse effects , Female , Heart Valve Prosthesis Implantation/adverse effects , Humans , Male , Mitral Valve/diagnostic imaging , Mitral Valve/surgery , Mitral Valve Insufficiency/diagnostic imaging , Mitral Valve Insufficiency/surgery , Retrospective Studies , Treatment Outcome
13.
JMIR Res Protoc ; 7(8): e10516, 2018 Aug 09.
Article in English | MEDLINE | ID: mdl-30093367

ABSTRACT

BACKGROUND: End-stage renal disease (ESRD) is the last stage of chronic kidney disease, mainly caused by type 2 diabetes mellitus and characterized by an increased mortality risk related to cardiovascular disease. Low-dose aspirin (acetylsalicylic acid or ASA) seems to effectively prevent cardiovascular events in patients with ESRD. However, the number of interventional studies in this population remains limited and the mechanisms of aspirin-related bleeding remain poorly understood. Aspirin's efficacy and safety may be modified by the presence of type 2 diabetes mellitus or platelet hyperreactivity. OBJECTIVE: The overall objective of this protocol is to (1) evaluate aspirin's safety and efficacy in reducing the risk of thrombotic events in patients with ESRD on hemodialysis and (2) examine whether aspirin's efficacy is modified by the presence of type 2 diabetes mellitus or platelet hyperreactivity. Specifically, the primary objective is to compare the 12-month rate of any thrombotic event (cardiac death, nonfatal myocardial infarction, nonfatal stroke, arteriovenous fistula thrombosis) and Thrombolysis in Myocardial Infarction (TIMI) major bleeding in patients treated with aspirin compared to those on placebo. Secondary objectives are to test for effect modification of treatment by the presence of type 2 diabetes mellitus or platelet hyperreactivity and compare the rate of TIMI minor bleeding between treatment groups. METHODS: We developed a protocol for a phase 2 randomized, single-center, placebo-controlled, triple-blind, superiority clinical trial to assess the prophylactic efficacy and safety of aspirin in patients with ESRD and on hemodialysis. It follows the ethical principles of the Declaration of Helsinki of the World Medical Association. A total of 342 participants would be enrolled over 12 months at a large dialysis center. Patients will be randomized in a 1:1 ratio and stratified by presence of type 2 diabetes mellitus and platelet hyperreactivity to receive either oral aspirin (100 mg/d) or placebo for a treatment period of 12 months. An intention-to-treat statistical analysis will be performed. RESULTS: The randomized clinical trial will be performed after approval by the ethical committee of the participating center and registration at ClinicalTrials.gov. CONCLUSIONS: We provide a protocol for a randomized controlled trial to evaluate the safety and efficacy of treatment with aspirin to reduce the risk of thrombotic events. In addition, such a study would further our understanding of the mechanism of aspirin-related bleeding and help identify subgroups of best-responders and patients with a higher risk of adverse events. REGISTERED REPORT IDENTIFIER: RR1-10.2196/10516.

14.
Sci Rep ; 7: 43179, 2017 03 07.
Article in English | MEDLINE | ID: mdl-28266587

ABSTRACT

Delafossite crystals are fascinating ternary oxides that have demonstrated transparent conductivity and ambipolar doping. Here we use a high-throughput approach based on density functional theory to find delafossite and related layered phases of composition ABX2, where A and B are elements of the periodic table, and X is a chalcogen (O, S, Se, and Te). From the 15 624 compounds studied in the trigonal delafossite prototype structure, 285 are within 50 meV/atom from the convex hull of stability. These compounds are further investigated using global structural prediction methods to obtain their lowest-energy crystal structure. We find 79 systems not present in the materials project database that are thermodynamically stable and crystallize in the delafossite or in closely related structures. These novel phases are then characterized by calculating their band gaps and hole effective masses. This characterization unveils a large diversity of properties, ranging from normal metals, magnetic metals, and some candidate compounds for p-type transparent electrodes.

15.
Phys Chem Chem Phys ; 18(29): 19926-32, 2016 Jul 20.
Article in English | MEDLINE | ID: mdl-27400409

ABSTRACT

We present simulations of the collapse under hydrostatic pressure of carbon nanotubes containing either water or carbon dioxide. We show that the molecules inside the tube alter the dynamics of the collapse process, providing either mechanical support and increasing the collapse pressure, or reducing mechanical stability. At the same time the nanotube acts as a nanoanvil, and the confinement leads to the nanostructuring of the molecules inside the collapsed tube. In this way, depending on the pressure and on the concentration of water or carbon dioxide inside the nanotube, we observe the formation of 1D molecular chains, 2D nanoribbons, and even molecular single and multi-walled nanotubes. The structure of the encapsulated molecules correlates with the mechanical response of the nanotube, opening up opportunities for the development of new devices or composite materials. Our analysis is quite general and it can be extended to other molecules in carbon nanotube nanoanvils, providing a strategy to obtain a variety of nano-objects with controlled features.

16.
J Chem Theory Comput ; 11(8): 3955-60, 2015 Aug 11.
Article in English | MEDLINE | ID: mdl-26574474

ABSTRACT

The dream of any solid-state theorist is to be able to predict new materials with tailored properties from scratch, i.e., without any input from experiment. Over the past decades, we have steadily approached this goal. Recent developments in the field of high-throughput calculations focused on finding the best material for specific applications. However, a key input for these techniques still had to be obtained experimentally, namely, the crystal structure of the materials. Here, we give a step further and show that one can indeed optimize material properties using as a single starting point the knowledge of the periodic table and the fundamental laws of quantum mechanics. This is done by combining state-of-the-art methods of global structure prediction that allow us to obtain the ground-state crystal structure of arbitrary materials, with an evolutionary algorithm that optimizes the chemical composition for the desired property. As a first showcase demonstration of our method, we perform an unbiased search for superhard materials and for transparent conductors. We stress that our method is completely general and can be used to optimize any property (or combination of properties) that can be calculated in a computer.

17.
J Chem Phys ; 142(2): 024710, 2015 Jan 14.
Article in English | MEDLINE | ID: mdl-25591380

ABSTRACT

Intermetallic Li-Al compounds are on the one hand key materials for light-weight engineering, and on the other hand, they have been proposed for high-capacity electrodes for Li batteries. We determine from first-principles the phase diagram of Li-Al binary crystals using the minima hopping structural prediction method. Beside reproducing the experimentally reported phases (LiAl, Li3Al2, Li9Al4, LiAl3, and Li2Al), we unveil a structural variety larger than expected by discovering six unreported binary phases likely to be thermodynamically stable. Finally, we discuss the behavior of the elastic constants and of the electric potential profile of all Li-Al stable compounds as a function of their stoichiometry.

18.
J Chem Theory Comput ; 10(12): 5625-9, 2014 Dec 09.
Article in English | MEDLINE | ID: mdl-26583245

ABSTRACT

We perform benchmark calculations for the ionization potential and electronic affinity of atoms and small molecules using several semilocal exchange-correlation functionals of density-functional theory with improved asymptotic behavior. We are particularly interested in a new generalized-gradient approximation for exchange [Armiento and Kümmel, Phys. Rev. Lett. 2013, 111, 036402] that provides an energy functional whose functional derivative yields a potential with better decay behavior. We find that it yields energies that are worse than traditional energy functionals and potentials that are less accurate than functionals that model directly the exchange-correlation potential. However, we find that this functional offers a excellent balance between the quality of the energy and of the potential and is therefore a good compromise for applications that require at the same time reasonable energies and good potentials.

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