Improved Potential Energy Surface of Ozone Constructed Using the Fitting by Permutationally Invariant Polynomial Function

New global potential energy surface for the ground electronic state of ozone is constructed at the complete basis set level of the multireference configuration interaction theory. A method of fitting the data points by analytical permutationally invariant polynomial function is adopted. A small set of 500 points is preoptimized using the old surface of ozone. In this procedure the positions of points in the configuration space are chosen such that the RMS deviation of the fit is minimized. New ab initio calculations are carried out at these points and are used to build new surface. Additional points are added to the vicinity of the minimum energy path in order to improve accuracy of the fit, particularly in the region where the surface of ozone exhibits a shallow van der Waals well. New surface can be used to study formation of ozone at thermal energies and its spectroscopy near the dissociation threshold

Dative and Electron-Sharing Bonding in C2F4

CTQ2015-65790-P, MINECO, Ministerio de Economía y CompetitividadThis workwas supportedby the Deutsche Forschungsgemein-schaft.Financial supportfrom the Spanish MINECO,grant CTQ2015-65790-

Surface Energies Arising in Microscopic Modeling of Martensitic Transformations

In this paper we construct and analyze a two-well Hamiltonian on a 2D atomic lattice. The two wells of the Hamiltonian are prescribed by two rank-one connected martensitic twins, respectively. By constraining the deformed configurations to special 1D atomic chains with position-dependent elongation vectors for the vertical direction, we show that the structure of ground states under appropriate boundary conditions is close to the macroscopically expected twinned configurations with additional boundary layers localized near the twinning interfaces. In addition, we proceed to a continuum limit, show asymptotic piecewise rigidity of minimizing sequences and rigorously derive the corresponding limiting form of the surface energy

Reduced scaling in electronic structure calculations using Cholesky decompositions

We demonstrate that substantial computational savings are attainable in electronic structure calculations using a Cholesky decomposition of the two-electron integral matrix. In most cases, the computational effort involved calculating the Cholesky decomposition is less than the construction of one Fock matrix using a direct O(N2) [email protected]

New approaches for the calibration of exchange-energy densities in local hybrid functionals

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.The ambiguity of exchange-energy densities is a fundamental challenge for the development of local hybrid functionals, or of other functionals based on a local mixing of exchange-energy densities. In this work, a systematic construction of semi-local calibration functions (CFs) for adjusting the exchange-energy densities in local hybrid functionals is provided, which directly links a given CF to an underlying semi-local exchange functional, as well as to the second-order gradient expansion of the exchange hole. Using successive steps of integration by parts allows the derivation of correction terms of increasing order, resulting in more and more complicated but also more flexible CFs. We derive explicit first-and second-order CFs (pig1 and pig2) based on B88 generalized-gradient approximation (GGA) exchange, and a first-order CF (tpig1) based on t-dependent B98 meta-GGA exchange. We combine these CFs with different long-range damping functions and evaluate them for calibration of LDA, B88 GGA, and TPSS meta-GGA exchange-energy densities. Based on a minimization of unphysical nondynamical correlation contributions in three noble-gas dimer potential-energy curves, free parameters in the CFs are optimized, and performance of various approaches in the calibration of different exchange-energy densities is compared. Most notably, the second-order pig2 CF provides the largest flexibility with respect to the diffuseness of the damping function. This suggests that higher-order CFs based on the present integration-by-parts scheme may be particularly suitable for the flexible construction of local hybrid functionals

Pooling problem: Alternate formulations and solution methods

Copyright @ 2004 INFORMSThe pooling problem, which is fundamental to the petroleum industry, describes a situation in which products possessing different attribute qualities are mixed in a series of pools in such a way that the attribute qualities of the blended products of the end pools must satisfy given requirements. It is well known that the pooling problem can be modeled through bilinear and nonconvex quadratic programming. In this paper, we investigate how best to apply a new branch-and-cut quadratic programming algorithm to solve the pooling problem. To this effect, we consider two standard models: One is based primarily on flow variables, and the other relies on the proportion. of flows entering pools. A hybrid of these two models is proposed for general pooling problems. Comparison of the computational properties of flow and proportion models is made on several problem instances taken from the literature. Moreover, a simple alternating procedure and a variable neighborhood search heuristic are developed to solve large instances and compared with the well-known method of successive linear programming. Solution of difficult test problems from the literature is substantially accelerated, and larger ones are solved exactly or approximately.This project was funded by Ultramar Canada and Luc Massé. The work of C. Audet was supported by NSERC (Natural Sciences and Engineering Research Council) fellowship PDF-207432-1998 and by CRPC (Center for Research on Parallel Computation). The work of J. Brimberg was supported by NSERC grant #OGP205041. The work of P. Hansen was supported by FCAR(Fonds pour la Formation des Chercheurs et l’Aide à la Recherche) grant #95ER1048, and NSERC grant #GP0105574

Preoperative exercise training prevents functional decline after lung resection surgery: a randomized, single-blind controlled trial

[Abstract] Objectives: To investigate the effects of a preoperative pulmonary rehabilitation programme in patients with lung cancer undergoing video-assisted thoracic surgery. Design: Randomized, single-blind controlled trial. Setting: Teaching hospital. Subjects: Patients with suspected or confirmed lung cancer undergoing video-assisted thoracic surgery. Intervention: Participants were randomized to either a prehabilitation group or a control group. Participants in the prehabilitation group underwent a combination of moderate endurance and resistance training plus breathing exercises three to five times per week. Main measures: The primary outcome of the study was exercise capacity. Secondary outcomes were muscle strength (Senior Fitness Test), health-related quality of life (Short-Form 36) and the postoperative outcomes. Patients were evaluated at baseline (before randomization), presurgery (only the prehabilitation group), after surgery and three months post-operatively. Results: A total of 40 patients were randomized and 22 finished the study (10 in the prehabilitation group and 12 in the control group). Three patients were lost to follow-up at three months. After the training, there was a statistically significant improvement in exercise tolerance (+397 seconds, p = 0.0001), the physical summary component of the SF-36 (+4.4 points, p = 0.008) and muscle strength (p < 0.01). There were no significant differences between groups after surgery. However, three months postoperatively, significant differences were found in the mean change of exercise capacity (p = 0.005), physical summary component (p = 0.001) and upper and lower body strength (p = 0.045 and p = 0.002). Conclusions: A pulmonary rehabilitation programme before video-assisted thoracic surgery seems to improve patients’ preoperative condition and may prevent functional decline after surger