Low-order Scaling G0W0G_0W_0 by Pair Atomic Density Fitting

We derive a low-scaling $G_0W_0$ algorithm for molecules, using pair atomic density fitting (PADF) and an imaginary time representation of the Green's function and describe its implementation in the Slater type orbital (STO) based Amsterdam density functional (ADF) electronic structure code. We demonstrate the scalability of our algorithm on a series of water clusters with up to 432 atoms and 7776 basis functions and observe asymptotic quadratic scaling with realistic threshold qualities controlling distance effects and basis sets of triple-$\zeta$ (TZ) plus double polarization quality. Also owing to a very small prefactor, with these settings a $G_0W_0$ calculation for the largest of these clusters takes only 240 CPU hours. With errors of 0.24 eV for HOMO energies in the GW100 database on the quadruple-$\zeta$ level, our implementation is less accurate than canonical all-electron implementations using the larger def2-QZVP GTO-tpye basis set. Apart from basis set errors, this is related to the well-known shortcomings of the GW space-time method using analytical continuation techniques as well as to numerical issues of the PADF-approach of accurately representing diffuse AO-products. We speculate, that these difficulties might be overcome by using optimized auxiliary fit sets with more diffuse functions of higher angular momenta. Despite these shortcomings, for subsets of medium and large molecules from the GW5000 database, the error of our approach using basis sets of TZ and augmented DZ quality is decreasing with system size. On the augmented DZ level we reproduce canonical, complete basis set limit extrapolated reference values with an accuracy of 80 meV on average for a set of 20 large organic molecules. We anticipate our algorithm, in its current form, to be very useful in the study of single-particle properties of large organic systems such as chromophores and acceptor molecules.Comment: final version as accepted by JCTC https://pubs.acs.org/doi/10.1021/acs.jctc.0c0069

Exploring the statically screened G3W2 correction to the GW self-energy: Charged excitations and total energies of finite systems

Electron correlation in finite and extended systems is often described in an effective single-particle framework within the $GW$ approximation. Here, we use the statically screened second-order exchange contribution to the self-energy ($G3W2$) to calculate a perturbative correction to the $GW$ self-energy. We use this correction to calculate total correlation energies of atoms, relative energies, as well as charged excitations of a wide range of molecular systems. We show that the second-order correction improves correlation energies with respect to the RPA and also improves relative energies for many, but not all considered systems. While the full $G3W2$ contribution does not give consistent improvements over $GW$, taking the average of $GW$ and $GW + G3W2$ generally gives excellent results. Improvements over quasiparticle self-consistent $GW$, which we show to give very accurate charged excitations in small and medium molecules by itself, are only minor. $G_0W_0$ quasiparticle energies evaluated with eigenvalue and orbitals from range-separated hybrids, however, are tremendously improved upon: The second-order corrected $G_0W_0$ outperforms all existing $GW$ methods for the systems considered herein and also does not come with substantially increased computational cost compared to $G_0W_0$ for systems with up to 100 atoms.Comment: Revised version as accepted by Physical review B (Phys. Rev. B 2022, 105, 125121, 10.1103/PhysRevB.105.125121) Compared to our first submission, a programming mistake in our first implementation has been corrected leading to different (better) result

GW100: A Slater Type Orbital Perspective

We calculate complete basis set (CBS) limit extrapolated ionization potentials (IP) and electron affinities (EA) with Slater Type Basis sets for the molecules in the GW100 database. To this end, we present two new Slater Type orbital (STO) basis sets of triple- (TZ) and quadruple-$\zeta$ (QZ) quality whose polarization is adequate for correlated-electron methods and which contain extra diffuse functions to be able to correctly calculate electron affinities of molecules with a positive Lowest Unoccupied Molecular Orbital (LUMO). We demonstrate, that going from TZ to QZ quality consistently reduces the basis set error of our computed IPs and EAs and we conclude that a good estimate of these quantities at the CBS limit can be obtained by extrapolation. With MADs from 70 to 85 meV, our CBS limit extrapolated ionization potentials are in good agreement with results from FHI-AIMS, TURBOMOLE, VASP and WEST while they differ by more than 130 meV on average from nanoGW. With a MAD of 160 meV, our electron affinities are also in good agreement with the WEST code. Especially for systems with positive LUMOs, the agreement is excellent. With respect to other codes, the STO type basis sets generally underestimate EAs of small molecules with strongly bound LUMOs. With 62 meV for IPs and 93 meV for EAs, we find much better agreement to CBS limit extrapolated results from FHI-AIMS for a set of 250 medium to large organic molecules.Comment: Published open access by Journal of chemical theory and computatio

Towards Pair Atomic Density Fitting for Correlation Energies with Benchmark Accuracy

Pair atomic density fitting (PADF) is a promising strategy to reduce the scaling with system size of quantum chemical methods for the calculation of the correlation energy like the direct random phase approximation (RPA) or second-order M{\o}ller-Plesset perturbation theory (MP2). PADF can however introduce large errors in correlation energies as the two-electron interaction energy is not guaranteed to be bounded from below. This issue can be partially alleviated by using very large fit sets, but this comes at the price of reduced efficiency and having to deal with near-linear dependencies in the fit set. In this work, we introduce an alternative methodology to overcome this problem that preserves the intrinsically favourable scaling of PADF. We first regularize the Fock matrix by projecting out parts of the basis set which gives rise to orbital products that are hard to describe by PADF. We then also apply this projector to the orbital coefficient matrix to improve the precision of PADF-MP2 and PADF-RPA. We systematically assess the accuracy of this new approach in a numerical atomic orbital framework using Slater Type Orbitals (STO) and correlation consistent Gaussian type basis sets up to quintuple-$\zeta$ quality for systems with more than 200 atoms. For the small and medium systems in the S66 database we show the maximum deviation of PADF-MP2 and PADF-RPA relative correlation energies to DF-MP2 and DF-RPA reference results to be 0.07 and 0.14 kcal/mol respectively. When the new projector method is used, the errors only slightly increase for large molecules and also when moderately sized fit sets are used the resulting errors are well under control. Finally, we demonstrate the computational efficiency of our algorithm by calculating the interaction energies of non-covalently bound complexes with more than 1000 atoms and 20000 atomic orbitals at the RPA@PBE/CC-pVTZ level of theory

Study of Protein Adsorption During Sterile Filtration of Protein Formulations by ILC

Protein adsorption is usually regarded as the main reason for filter fouling in sterile filtration of protein formulations. To achieve a better insight into this phenomenon, protein adsorption was studied during filtration of stabilized bovine serum albumin (BSA) and γ‐globulin formulations through 0.2-µm microfilter membranes by inverse liquid chromatography (ILC). Adsorption processes can be studied with this method by measurement of breakthrough curves. The change of the concentration in the fluid phase is measured with high accuracy by an inline UV-detector. © 2020 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei

Five Fractions versus Seven Fractions SBRT for Intermediate- and High-Risk Prostate Cancer: A Propensity Score Matched Pair Analysis.

PURPOSE To compare two stereotactic body radiotherapy (SBRT) regimens in patients with intermediate- or high-risk prostate cancer with regards toxicity and efficacy. METHODS/MATERIAL We retrospectively collected data from 198 patients treated with SBRT for prostate cancer at two different institutions. Patients received either 35-36.25 Gy in five fractions (group A) using Cyberknife robotic platform or 42.7 Gy in seven fractions (group B) using a C-arm LINAC (image-guided). Propensity score matching was done (2:1 nearest neighbor matching without replacement), resulting in 120 patients (80 patients for group A, 40 patients for group B). Toxicity, PSA nadir, biochemical failure and disease-free survival (DFS) were analyzed. RESULTS Median follow up of all patients was 13 months (range 1-91 months). Overall, 23.3% of patients had ≥G2 acute GU toxicity (21.1% group A versus 30% group B (p = 0.222)) and 6.6% of patients ≥G2 GI toxicity (2.5% versus 15% (p = 0.010)). There was one acute G3 GU toxicity in arm A and one acute G4 rectal bleeding in group B (anticoagulated patient). Regarding late toxicity, 14.1% of patients had ≥G2 late GU toxicity (17.4% versus 6.6% (p = 0.159)) and 5.0% of patients had ≥G2 late GI toxicity (1.4% versus 13.3% (p = 0.013)). There was one G3 late GU toxicity in arm B and two G3 late GI toxicities, one in each arm. Relative median PSA reduction was 92.4% (-53.9-99.9%) from baseline PSA (93.7% (-53.9-99.9%) in group A versus 87.7% (39.8-99.9%) in group B (p = 0.043). In total, 4.2% of patients had biochemical relapse, 5.0% in group A and 2.5% in group B (p = 0.518). One-year DFS in the overall cohort was 97.3%, 98.8% in group A and 94.3% in group B (p = 0.318). CONCLUSION Both SBRT regimens have acceptable acute and late toxicity and good efficacy. There are significantly more GI toxicities in the seven-fraction regimen. Longer follow-up is warranted for better comparison of long-term efficacy

Bulge and Clump Evolution in Hubble Ultra Deep Field Clump Clusters, Chains and Spiral Galaxies

Clump clusters and chain galaxies in the Hubble Ultra Deep Field are examined for bulges in the NICMOS images. Approximately 50% of the clump clusters and 30% of the chains have relatively red and massive clumps that could be young bulges. Magnitudes and colors are determined for these bulge-like objects and for the bulges in spiral galaxies, and for all of the prominent star-formation clumps in these three galaxy types. The colors are fitted to population evolution models to determine the bulge and clump masses, ages, star-formation rate decay times, and extinctions. The results indicate that bulge-like objects in clump cluster and chain galaxies have similar ages and 2 to 5 times larger masses compared to the star-formation clumps, while the bulges in spirals have ~6 times larger ages and 20 to 30 times larger masses than the clumps. All systems appear to have an underlying red disk population. The masses of star-forming clumps are typically in a range from 10^7 to 10^8 Msun; their ages have a wide range around ~10^2 Myr. Ages and extinctions both decrease with redshift. Star formation is probably the result of gravitational instabilities in the disk gas, in which case the large clump mass in the UDF is the result of a high gas velocity dispersion, 30 km/s or more, combined with a high gas mass column density, ~100 Msun/pc^2. Because clump clusters and chains dominate disk galaxies beyond z~1, the observations suggest that these types represent an early phase in the formation of modern spiral galaxies, when the bulge and inner disk formed.Comment: ApJ in press February 2009, vol. 691, 23 pages and 20 figure

The impact of surgical site infection—a cost analysis

Purpose: Surgical site infection (SSI) occurs in up to 25% of patients after elective laparotomy. We aimed to determine the effect of SSI on healthcare costs and patients' quality of life. Methods: In this post hoc analysis based on the RECIPE trial, we studied a 30-day postoperative outcome of SSI in a single-center, prospective randomized controlled trial comparing subcutaneous wound irrigation with 0.04% polyhexanide to 0.9% saline after elective laparotomy. Total medical costs were analyzed accurately per patient with the tool of our corporate controlling team which is based on diagnosis-related groups in Germany. Results: Between November 2015 and May 2018, 456 patients were recruited. The overall rate of SSI was 28.2%. Overall costs of inpatient treatment were higher in the group with SSI: median 16.685 euro; 19.703 USD (IQR 21.638 euro; 25.552 USD) vs. median 11.235 euro; 13.276 USD (IQR 11.564 euro; 13.656 USD); p < 0.001. There was a difference in surgery costs (median 6.664 euro; 7.870 USD with SSI vs. median 5.040 euro; 5.952 USD without SSI; p = 0.001) and costs on the surgical ward (median 8.404 euro; 9.924 USD with SSI vs. median 4.690 euro; 5.538 USD without SSI; p < 0.001). Patients with SSI were less satisfied with the cosmetic result (4.3% vs. 16.2%; p < 0.001). Overall costs for patients who were irrigated with saline were median 12.056 euro; 14.237 USD vs. median 12.793 euro; 15.107 USD in the polyhexanide group (p = 0.52). Conclusion: SSI after elective laparotomy increased hospital costs substantially. This is an additional reason why the prevention of SSI is important. Overall costs for intraoperative wound irrigation with saline were comparable with polyhexanide

PET/CT radiomics for prediction of hyperprogression in metastatic melanoma patients treated with immune checkpoint inhibitors

PurposeThis study evaluated pretreatment 2[18F]fluoro-2-deoxy-D-glucose (FDG)-PET/CT-based radiomic signatures for prediction of hyperprogression in metastatic melanoma patients treated with immune checkpoint inhibition (ICI).Material and methodFifty-six consecutive metastatic melanoma patients treated with ICI and available imaging were included in the study and 330 metastatic lesions were individually, fully segmented on pre-treatment CT and FDG-PET imaging. Lesion hyperprogression (HPL) was defined as lesion progression according to RECIST 1.1 and doubling of tumor growth rate. Patient hyperprogression (PD-HPD) was defined as progressive disease (PD) according to RECIST 1.1 and presence of at least one HPL. Patient survival was evaluated with Kaplan-Meier curves. Mortality risk of PD-HPD status was assessed by estimation of hazard ratio (HR). Furthermore, we assessed with Fisher test and Mann-Whitney U test if demographic or treatment parameters were different between PD-HPD and the remaining patients. Pre-treatment PET/CT-based radiomic signatures were used to build models predicting HPL at three months after start of treatment. The models were internally validated with nested cross-validation. The performance metric was the area under receiver operating characteristic curve (AUC).ResultsPD-HPD patients constituted 57.1% of all PD patients. PD-HPD was negatively related to patient overall survival with HR=8.52 (95%CI 3.47-20.94). Sixty-nine lesions (20.9%) were identified as progressing at 3 months. Twenty-nine of these lesions were classified as hyperprogressive, thereby showing a HPL rate of 8.8%. CT-based, PET-based, and PET/CT-based models predicting HPL at three months after the start of treatment achieved testing AUC of 0.703 +/- 0.054, 0.516 +/- 0.061, and 0.704 +/- 0.070, respectively. The best performing models relied mostly on CT-based histogram features.ConclusionsFDG-PET/CT-based radiomic signatures yield potential for pretreatment prediction of lesion hyperprogression, which may contribute to reducing the risk of delayed treatment adaptation in metastatic melanoma patients treated with ICI

Skyrmion Hall Effect Revealed by Direct Time-Resolved X-Ray Microscopy

Magnetic skyrmions are highly promising candidates for future spintronic applications such as skyrmion racetrack memories and logic devices. They exhibit exotic and complex dynamics governed by topology and are less influenced by defects, such as edge roughness, than conventionally used domain walls. In particular, their finite topological charge leads to a predicted "skyrmion Hall effect", in which current-driven skyrmions acquire a transverse velocity component analogous to charged particles in the conventional Hall effect. Here, we present nanoscale pump-probe imaging that for the first time reveals the real-time dynamics of skyrmions driven by current-induced spin orbit torque (SOT). We find that skyrmions move at a well-defined angle {\Theta}_{SH} that can exceed 30{\deg} with respect to the current flow, but in contrast to theoretical expectations, {\Theta}_{SH} increases linearly with velocity up to at least 100 m/s. We explain our observation based on internal mode excitations in combination with a field-like SOT, showing that one must go beyond the usual rigid skyrmion description to unravel the dynamics.Comment: pdf document arxiv_v1.1. 24 pages (incl. 9 figures and supplementary information