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| 4. |
- Ahmadzadeh, Karan, et al.
(författare)
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Efficient implementation of isotropic cubic response functions for two-photon absorption cross sections within the self-consistent field approximation
- 2021
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 154:2
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Tidskriftsartikel (refereegranskat)abstract
- Within the self-consistent field approximation, computationally tractable expressions for the isotropic second-order hyperpolarizability have been derived and implemented for the calculation of two-photon absorption cross sections. The novel tensor average formulation presented in this work allows for the evaluation of isotropic damped cubic response functions using only similar to 3.3% (one-photon off-resonance regions) and similar to 10% (one-photon resonance regions) of the number of auxiliary Fock matrices required when explicitly calculating all the needed individual tensor components. Numerical examples of the two-photon absorption cross section in the one-photon off-resonance and resonance regions are provided for alanine-tryptophan and 2,5-dibromo-1,4-bis(2-(4-diphenylaminophenyl)vinyl)-benzene. Furthermore, a benchmark set of 22 additional small- and medium-sized organic molecules is considered. In all these calculations, a quantitative assessment is made of the reduced and approximate forms of the cubic response function in the one-photon off-resonance regions and results demonstrate a relative error of less than similar to 5% when using the reduced expression as compared to the full form of the isotropic cubic response function.
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| 5. |
- Brand, Manuel, et al.
(författare)
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Efficient and Parallel Implementation of Real and Complex Response Functions Employing the Second-Order Algebraic-Diagrammatic Construction Scheme for the Polarization Propagator
- 2023
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Ingår i: Journal of Chemical Theory and Computation. - : American Chemical Society (ACS). - 1549-9618 .- 1549-9626. ; 20:1, s. 103-113
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Tidskriftsartikel (refereegranskat)abstract
- We present the implementation of an efficient matrix-folded formalism for the evaluation of complex response functions and the calculation of transition properties at the level of the second-order algebraic-diagrammatic construction (ADC(2)) scheme. The underlying algorithms, in combination with the adopted hybrid MPI/OpenMP parallelization strategy, enabled calculations of the UV/vis spectra of a guanine oligomer series ranging up to 1032 contracted basis functions, thereby utilizing vast computational resources from up to 32,768 CPU cores. Further analysis of the convergence behavior of the involved iterative subspace algorithms revealed the superiority of a frequency-separated treatment of response equations even for a large spectral window, including 101 frequencies. We demonstrate the applicability to general quantum mechanical operators by the first reported electronic circular dichroism spectrum calculated with a complex polarization propagator approach at the ADC(2) level of theory.
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| 6. |
- Brand, Manuel, et al.
(författare)
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Efficient parallel implementation of complex response functions employing the algebraic-diagrammatic construction scheme
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- We present the derivation and implementation of an efficient matrix-folded formalism for the evaluation of complex response functions at the level of the second-order algebraic-diagrammatic construction ADC(2) scheme. The adopted hybrid MPI/OpenMP parallelization strategy enables the utilization of vast computational resources without significant performance losses as demonstrated by consistent size-scalings for the computationally most demanding steps obtained from calculations of the UV/vis spectra of a guanine oligomer series ranging up to 1,032 contracted basis functions. Further analysis of the convergence behavior of the involved iterative subspace algorithm revealed the superiority of a frequency-separated treatment of response equations even for a large spectral window including 101 frequencies. We demonstrate the applicability to general quantum mechanical operators by the first reported electric circular dichroism spectrum calculated with the complex polarization propagator approach at the ADC(2) level of theory.
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| 7. |
- Brand, Manuel
(författare)
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Implementation of complex polarization propagator theory for linear response properties of large molecular systems
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Since its beginning, the remarkable development from the first commercially available computers toward exascale supercomputers just within the span of a lifetime has been closely intertwined with the perpetual quest for the utilization of the arising computing power for the avail of theoretical chemistry. With the aim of further pushing the limits of computationally accessible molecular system sizes, this thesis includes the presentation of programming efforts, which brought forth two quantum chemical software codes, as well as a range of ab initio studies on carbon-based systems, enabled by the former.The VeloxChem and Gator programs, developed for spectroscopy simulations at the level of density-functional theory (DFT) and correlated wave function methods, respectively, employ a hybrid message passing interface (MPI)/open multiprocessing (OpenMP) parallelization scheme embedded in a modular program structure written in a Python/C++ layered fashion for the execution in contemporary high-performance computing (HPC) environments. Included numerical solvers for the evaluation of real and complex linear response functions in combination with the parallel construction of auxiliary Fock matrices enable the efficient calculation of one-photon absorption or electronic circular dichroism (CD) spectra in the ultraviolet/visible (UV/vis) or X-ray spectral region, as well as van der Waals C6 dispersion coefficients.Employing the VeloxChem program in two comprehensive investigations, the C6 dispersion coefficients of carbon fullerenes up to a system size of C540 and the CD spectra of carbohelicenes ranging from CH[5] to CH[30] have been calculated at the DFT level of theory. The revealed non-additive scaling with respect to the number of carbon atoms of N2.2 in the former and nontrivial CD band progressions, arguably linked to the number of overlapping layers in the helical conjugated systems, in the latter rectify the current conception in their respective fields.In a benchmark for the Gator program on a series of guanine oligomers, the full UV/vis spectrum for a tetrad was calculated at the level of a second-order algebraic-diagrammatic construction (ADC(2)) scheme in just under 15 hours by efficient employment of 32,768 central processing unit (CPU) cores.Exceeding the limit of 10,000 and 1,000 contracted basis functions for a treatment with the DFT and ADC(2) methods, respectively, these practical examples demonstrate the capability of VeloxChem and Gator to harness vast computational resources made available by contemporary and future HPC systems and thereby routinely address scopes of system sizes that were previously out of reach.
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| 8. |
- Brand, Manuel, et al.
(författare)
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Nontrivial spectral band progressions in electronic circular dichroism spectra of carbohelicenes revealed by linear response calculations
- 2022
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 24:32, s. 19321-19332
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate that contemporary computational resources allow for accurate theoretical studies of systems matching recent advances in experimental helicene chemistry. Concerned with first-principles calculations of carbohelicenes, our work surpasses CH[12] as the largest system investigated to date and unravels trends in the electronic structure of the low-lying states of the homologous series. Utilizing a highly efficient implementation of linear response algorithms, we present electronic circular dichroism (CD) spectra of carbohelicenes ranging from CH[5] to CH[30] at the level of Kohn-Sham density-functional theory. Our results for a systematic increase in system size show the emergence of new CD bands that subsequently rise to intensities dominating the spectrum. The spectral band progressions exhibit a periodicity directly linked to the number of overlapping layers of conjugation. While our findings rectify the current understanding of the electronic structure of carbohelicenes, they also serve as a general call for caution regarding the extrapolation of trends from small system ranges.
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| 9. |
- Brand, Manuel, et al.
(författare)
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Size-dependent polarizabilities and van der Waals dispersion coefficients of fullerenes from large-scale complex polarization propagator calculations
- 2021
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Ingår i: Journal of Chemical Physics. - : AMER INST PHYSICS. - 0021-9606 .- 1089-7690. ; 154:7
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Tidskriftsartikel (refereegranskat)abstract
- While the anomalous non-additive size-dependencies of static dipole polarizabilities and van der Waals C-6 dispersion coefficients of carbon fullerenes are well established, the widespread reported scalings for the latter (ranging from N-2.2 to N-2.8) call for a comprehensive first-principles investigation. With a highly efficient implementation of the linear complex polarization propagator, we have performed Hartree-Fock and Kohn-Sham density functional theory calculations of the frequency-dependent polarizabilities for fullerenes consisting of up to 540 carbon atoms. Our results for the static polarizabilities and C-6 coefficients show scalings of N-1.2 and N-2.2, respectively, thereby deviating significantly from the previously reported values obtained with the use of semi-classical/empirical methods. Arguably, our reported values are the most accurate to date as they represent the first ab initio or first-principles treatment of fullerenes up to a convincing system size.
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| 10. |
- Ellinghaus, David, et al.
(författare)
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Association between variants of PRDM1 and NDP52 and Crohn's disease, based on exome sequencing and functional studies
- 2013
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Ingår i: Gastroenterology. - : Elsevier BV. - 0016-5085 .- 1528-0012. ; 145:2, s. 339-347
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND & AIMS: Genome-wide association studies (GWAS) have identified 140 Crohn's disease (CD) susceptibility loci. For most loci, the variants that cause disease are not known and the genes affected by these variants have not been identified. We aimed to identify variants that cause CD through detailed sequencing, genetic association, expression, and functional studies.METHODS: We sequenced whole exomes of 42 unrelated subjects with CD and 5 healthy subjects (controls) and then filtered single nucleotide variants by incorporating association results from meta-analyses of CD GWAS and in silico mutation effect prediction algorithms. We then genotyped 9348 subjects with CD, 2868 subjects with ulcerative colitis, and 14,567 control subjects and associated variants analyzed in functional studies using materials from subjects and controls and in vitro model systems.RESULTS: We identified rare missense mutations in PR domain-containing 1 (PRDM1) and associated these with CD. These mutations increased proliferation of T cells and secretion of cytokines on activation and increased expression of the adhesion molecule L-selectin. A common CD risk allele, identified in GWAS, correlated with reduced expression of PRDM1 in ileal biopsy specimens and peripheral blood mononuclear cells (combined P = 1.6 x 10(-8)). We identified an association between CD and a common missense variant, Val248Ala, in nuclear domain 10 protein 52 (NDP52) (P = 4.83 x 10(-9)). We found that this variant impairs the regulatory functions of NDP52 to inhibit nuclear factor kappa B activation of genes that regulate inflammation and affect the stability of proteins in Toll-like receptor pathways.CONCLUSIONS: We have extended the results of GWAS and provide evidence that variants in PRDM1 and NDP52 determine susceptibility to CD. PRDM1 maps adjacent to a CD interval identified in GWAS and encodes a transcription factor expressed by T and B cells. NDP52 is an adaptor protein that functions in selective autophagy of intracellular bacteria and signaling molecules, supporting the role of autophagy in the pathogenesis of CD.
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| 11. |
- Engert, Andreas, et al.
(författare)
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The European Hematology Association Roadmap for European Hematology Research : a consensus document
- 2016
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Ingår i: Haematologica. - Pavia, Italy : Ferrata Storti Foundation (Haematologica). - 0390-6078 .- 1592-8721. ; 101:2, s. 115-208
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Tidskriftsartikel (refereegranskat)abstract
- The European Hematology Association (EHA) Roadmap for European Hematology Research highlights major achievements in diagnosis and treatment of blood disorders and identifies the greatest unmet clinical and scientific needs in those areas to enable better funded, more focused European hematology research. Initiated by the EHA, around 300 experts contributed to the consensus document, which will help European policy makers, research funders, research organizations, researchers, and patient groups make better informed decisions on hematology research. It also aims to raise public awareness of the burden of blood disorders on European society, which purely in economic terms is estimated at (sic)23 billion per year, a level of cost that is not matched in current European hematology research funding. In recent decades, hematology research has improved our fundamental understanding of the biology of blood disorders, and has improved diagnostics and treatments, sometimes in revolutionary ways. This progress highlights the potential of focused basic research programs such as this EHA Roadmap. The EHA Roadmap identifies nine 'sections' in hematology: normal hematopoiesis, malignant lymphoid and myeloid diseases, anemias and related diseases, platelet disorders, blood coagulation and hemostatic disorders, transfusion medicine, infections in hematology, and hematopoietic stem cell transplantation. These sections span 60 smaller groups of diseases or disorders. The EHA Roadmap identifies priorities and needs across the field of hematology, including those to develop targeted therapies based on genomic profiling and chemical biology, to eradicate minimal residual malignant disease, and to develop cellular immunotherapies, combination treatments, gene therapies, hematopoietic stem cell treatments, and treatments that are better tolerated by elderly patients.
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| 12. |
- Hollestelle, Antoinette, et al.
(författare)
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No clinical utility of KRAS variant rs61764370 for ovarian or breast cancer
- 2016
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Ingår i: Gynecologic Oncology. - : Elsevier BV. - 0090-8258 .- 1095-6859. ; 141:2, s. 386-401
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Tidskriftsartikel (refereegranskat)abstract
- Objective Clinical genetic testing is commercially available for rs61764370, an inherited variant residing in a KRAS 3′ UTR microRNA binding site, based on suggested associations with increased ovarian and breast cancer risk as well as with survival time. However, prior studies, emphasizing particular subgroups, were relatively small. Therefore, we comprehensively evaluated ovarian and breast cancer risks as well as clinical outcome associated with rs61764370. Methods Centralized genotyping and analysis were performed for 140,012 women enrolled in the Ovarian Cancer Association Consortium (15,357 ovarian cancer patients; 30,816 controls), the Breast Cancer Association Consortium (33,530 breast cancer patients; 37,640 controls), and the Consortium of Modifiers of BRCA1 and BRCA2 (14,765 BRCA1 and 7904 BRCA2 mutation carriers). Results We found no association with risk of ovarian cancer (OR = 0.99, 95% CI 0.94-1.04, p = 0.74) or breast cancer (OR = 0.98, 95% CI 0.94-1.01, p = 0.19) and results were consistent among mutation carriers (BRCA1, ovarian cancer HR = 1.09, 95% CI 0.97-1.23, p = 0.14, breast cancer HR = 1.04, 95% CI 0.97-1.12, p = 0.27; BRCA2, ovarian cancer HR = 0.89, 95% CI 0.71-1.13, p = 0.34, breast cancer HR = 1.06, 95% CI 0.94-1.19, p = 0.35). Null results were also obtained for associations with overall survival following ovarian cancer (HR = 0.94, 95% CI 0.83-1.07, p = 0.38), breast cancer (HR = 0.96, 95% CI 0.87-1.06, p = 0.38), and all other previously-reported associations. Conclusions rs61764370 is not associated with risk of ovarian or breast cancer nor with clinical outcome for patients with these cancers. Therefore, genotyping this variant has no clinical utility related to the prediction or management of these cancers.
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- Kolodner, Elliot K, et al.
(författare)
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A cloud environment for data-intensive storage services
- 2011
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Ingår i: IEEE third international conference on Cloud computing technology and science (CloudCom), 2011. - : IEEE conference proceedings. - 9781467300902 ; , s. 357-366
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Konferensbidrag (refereegranskat)abstract
- The emergence of cloud environments has made feasible the delivery of Internet-scale services by addressing a number of challenges such as live migration, fault tolerance and quality of service. However, current approaches do not tackle key issues related to cloud storage, which are of increasing importance given the enormous amount of data being produced in today's rich digital environment (e.g. by smart phones, social networks, sensors, user generated content). In this paper we present the architecture of a scalable and flexible cloud environment addressing the challenge of providing data-intensive storage cloud services through raising the abstraction level of storage, enabling data mobility across providers, allowing computational and content-centric access to storage and deploying new data-oriented mechanisms for QoS and security guarantees. We also demonstrate the added value and effectiveness of the proposed architecture through two real-life application scenarios from the healthcare and media domains.
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| 14. |
- Rehn, D. R., et al.
(författare)
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Gator : A Python-driven program for spectroscopy simulations using correlated wave functions
- 2021
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Ingår i: Wiley Interdisciplinary Reviews. Computational Molecular Science. - : John Wiley and Sons Inc. - 1759-0876 .- 1759-0884. ; 11:6
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Tidskriftsartikel (refereegranskat)abstract
- The Gator program has been developed for computational spectroscopy and calculations of molecular properties using real and complex propagators at the correlated level of wave function theory. Currently, the focus lies on methods based on the algebraic diagrammatic construction (ADC) scheme up to the third order of perturbation theory. An auxiliary Fock matrix-driven implementation of the second-order ADC method for excitation energies has been realized with an underlying hybrid MPI/OpenMP parallelization scheme suitable for execution in high-performance computing cluster environments. With a modular and object-oriented program structure written in a Python/C++ layered fashion, Gator additionally enables time-efficient prototyping of novel scientific approaches, as well as interactive notebook-driven training of students in quantum chemistry. This article is categorized under: Computer and Information Science > Computer Algorithms and Programming Electronic Structure Theory > Ab Initio Electronic Structure Methods Software > Quantum Chemistry.
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| 16. |
- Rinkevicius, Zilvinas, et al.
(författare)
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VeloxChem : A Python-driven density-functional theory program for spectroscopy simulations in high-performance computing environments
- 2019
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Ingår i: Wiley Interdisciplinary Reviews. Computational Molecular Science. - : Blackwell Publishing Inc.. - 1759-0876 .- 1759-0884.
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Tidskriftsartikel (refereegranskat)abstract
- An open-source program named VeloxChem has been developed for the calculation of electronic real and complex linear response functions at the levels of Hartree–Fock and Kohn–Sham density functional theories. With an object-oriented program structure written in a Python/C++ layered fashion, VeloxChem enables time-efficient prototyping of novel scientific approaches without sacrificing computational efficiency, so that molecular systems involving up to and beyond 500 second-row atoms (or some 10,000 contracted and in part diffuse Gaussian basis functions) can be routinely addressed. In addition, VeloxChem is equipped with a polarizable embedding scheme for the treatment of the classical electrostatic interactions with an environment that in turn is modeled by atomic site charges and polarizabilities. The underlying hybrid message passing interface (MPI)/open multiprocessing (OpenMP) parallelization scheme makes VeloxChem suitable for execution in high-performance computing cluster environments, showing even slightly beyond linear scaling for the Fock matrix construction with use of up to 16,384 central processing unit (CPU) cores. An efficient—with respect to convergence rate and overall computational cost—multifrequency/gradient complex linear response equation solver enables calculations not only of conventional spectra, such as visible/ultraviolet/X-ray electronic absorption and circular dichroism spectra, but also time-resolved linear response signals as due to ultra-short weak laser pulses. VeloxChem distributed under the GNU Lesser General Public License version 2.1 (LGPLv2.1) license and made available for download from the homepage https://veloxchem.org. This article is categorized under: Software > Quantum Chemistry Electronic Structure Theory > Density Functional Theory Theoretical and Physical Chemistry > Spectroscopy.
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| 17. |
- Zeng, Chenjie, et al.
(författare)
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Identification of independent association signals and putative functional variants for breast cancer risk through fine-scale mapping of the 12p11 locus
- 2016
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Ingår i: Breast Cancer Research. - : Springer Science and Business Media LLC. - 1465-5411 .- 1465-542X. ; 18
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Tidskriftsartikel (refereegranskat)abstract
- Background: Multiple recent genome-wide association studies (GWAS) have identified a single nucleotide polymorphism (SNP), rs10771399, at 12p11 that is associated with breast cancer risk. Method: We performed a fine-scale mapping study of a 700 kb region including 441 genotyped and more than 1300 imputed genetic variants in 48,155 cases and 43,612 controls of European descent, 6269 cases and 6624 controls of East Asian descent and 1116 cases and 932 controls of African descent in the Breast Cancer Association Consortium (BCAC; http://bcac.ccge.medschl.cam.ac.uk/), and in 15,252 BRCA1 mutation carriers in the Consortium of Investigators of Modifiers of BRCA1/2 (CIMBA). Stepwise regression analyses were performed to identify independent association signals. Data from the Encyclopedia of DNA Elements project (ENCODE) and the Cancer Genome Atlas (TCGA) were used for functional annotation. Results: Analysis of data from European descendants found evidence for four independent association signals at 12p11, represented by rs7297051 (odds ratio (OR) = 1.09, 95 % confidence interval (CI) = 1.06-1.12; P = 3 x 10(-9)), rs805510 (OR = 1.08, 95 % CI = 1.04-1.12, P = 2 x 10(-5)), and rs1871152 (OR = 1.04, 95 % CI = 1.02-1.06; P = 2 x 10(-4)) identified in the general populations, and rs113824616 (P = 7 x 10(-5)) identified in the meta-analysis of BCAC ER-negative cases and BRCA1 mutation carriers. SNPs rs7297051, rs805510 and rs113824616 were also associated with breast cancer risk at P < 0.05 in East Asians, but none of the associations were statistically significant in African descendants. Multiple candidate functional variants are located in putative enhancer sequences. Chromatin interaction data suggested that PTHLH was the likely target gene of these enhancers. Of the six variants with the strongest evidence of potential functionality, rs11049453 was statistically significantly associated with the expression of PTHLH and its nearby gene CCDC91 at P < 0.05. Conclusion: This study identified four independent association signals at 12p11 and revealed potentially functional variants, providing additional insights into the underlying biological mechanism(s) for the association observed between variants at 12p11 and breast cancer risk.
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