Search results for "Potential"
showing 10 items of 3348 documents
Alternative single-reference coupled cluster approaches for multireference problems: the simpler, the better.
2011
We report a general implementation of alternative formulations of single-reference coupled cluster theory (extended, unitary, and variational) with arbitrary-order truncation of the cluster operator. These methods are applied to compute the energy of Ne and the equilibrium properties of HF and C(2). Potential energy curves for the dissociation of HF and the BeH(2) model computed with the extended, variational, and unitary coupled cluster approaches are compared to those obtained from the multireference coupled cluster approach of Mukherjee et al. [J. Chem. Phys. 110, 6171 (1999)] and the internally contracted multireference coupled cluster approach [F. A. Evangelista and J. Gauss, J. Chem. …
Relativistic coupled cluster calculations of the electronic structure of KrH+, XeH+ and RnH+
2012
Potential energy curves of NgH+ cations (Ng = Kr, Xe, Rn) were obtained by using four-component relativistic CCSD(T) coupled cluster calculations. Dissociation energies, equilibrium bond lengths, electronic properties, such as dipole moments and electric field gradients at the nuclei, and the related spectroscopic parameters of the electronic ground state have been determined. The results obtained for KrH+ and XeH+ are in good agreement with available experimental data, while those for RnH+ have been determined for the first time at this level of theory.
GERMANIUM DICARBIDE: EVIDENCE FOR A T−SHAPED GROUND STATE STRUCTURE
2017
The equilibrium structure of germanium dicarbide GeC2 has been an open question since the late 1950s. Although most high-level quantum calculations predict an L-shaped geometry, a T-shaped or even a linear geometry cannot be ruled out because of the very flat potential energy surface. By recording the rotational spectrum of this dicarbide using sensitive microwave and millimeter techniques, we unambiguously establish that GeC2 adopts a vibrationally averaged T-shaped structure in its ground state. From analysis of 14 isotopologues, a precise r0 structure has been derived, yielding a Ge–C bond length of 1.952(1) A and an apex angle of 38.7(2)°.
Comparison of various CI treatments for the description of potential curves for the lowest three states of O2
1972
Abstract Various ab initio CI treatments are reported for the 3 Σ − g , 1 Δ g and 1 Σ + g states of O 2 with particular emphasis on the agreement obtained between calculated and experimental results for binding energies and bond distances of these species and also for transition energies between them. The utility of off-center s and p gaussians in describing the bonding process is stressed and the possibility of optimizing the configurations used in the calculations at each internuclear distance is considered.
Brain Activity Characterization Induced by Alcoholic Addiction: Spectral and Causality Analysis of Brain Areas Related to Control and Reinforcement o…
2014
Addiction to drugs generates modifications in the brain structure and its functions. In this work, an experimental model is described, using rats to characterize the brain activity induced by alcohol addiction. Four records were obtained using electrodes located in brain areas related to impulsivity control and reinforcement, i.e. the prelimbic (PL) and infralimbic (IL) cortex, together with the hippocampus (HPC). In the records, three main events related to the drinking action were selected: in the previous minute (T1), the first minute while drinking (T2) and the first minute after stopping drinking (T3).
Somatosensory evoked potentials aiding the diagnosis of brain death.
1988
SEP were recorded in 14 patients, who fulfilled the clinical and electroencephalographic criteria of brain death. The results are compared with the respective ones in healthy subjects. Beside the absence of cortical N 20 in each brain dead patient, reduction of amplitude or absence of near field negativity (N 13b) from upper neck regardless of the position of the reference electrode represents the predominant result. The near field potential from the lower neck (N 13a) was unaffected. The counterpart in the far field potential recorded from F z was amplitude reduction of P 13. These results suggest that the dissociation of N 13a and N 13b can confirm the diagnosis of brain death. Moreover t…
Bioaccessibility of Enniatins A, A1, B, and B1 in Different Commercial Breakfast Cereals, Cookies, and Breads of Spain
2013
Fusarotoxins enniatins (ENs) can represent a potential risk as natural contaminants of cereal commodities. However, only their bioaccessible fraction can exert a toxicity. The purpose of this study was to determine the ENs A, A₁, B, and B₁ bioaccessibility added in 1.5 and 3.0 μmol/g concentrations in breakfast cereals, cookies, and breads using a simulated in vitro gastrointestinal extraction model. Bioaccessibility values ranged between 40.4 ± 1.9 and 79.9 ± 2.8%. The lower values were 50.1, 40.4, 43.9, and 46.3% in wheat bran with fibers, and the higher values were 79.9, 64.2, 69.8, and 73.6% in white loaf bread for the ENs A, A₁, B, and B₁, respectively. Food composition, compounds stru…
Shakedown Analysis by Elastic Simulation
2000
Shakedown analysis of elastic plastic structures is widely credited as a valuable analytical/numerical tool for design purposes. For complex structures and loading conditions, e. g. for fast breeder nuclear reactor plants, full inelastic analysis is rarely performed, practically never within the early stages of the design advancement and the inherent decision process. The essential information therein needed can in fact be obtained, at moderate computational costs, by application of the shakedown methods and rules, at least within some limits related to the present developments of shakedown theory and its applicability to practical engineering problems, see e. g. Ponter et al. (1990), Carte…
Bridging the gap between research and practice : using phenomenographic findings to develop training for career practitioners
2021
AbstractThis study contends that phenomenography offers both a useful research method and practical tools for developing education and training for career practitioners. After introducing the basic principles of phenomenography, the study reviews previous research on its potential in developing pedagogical practices. It explores how the phenomenographic findings were utilized to design an online skills training programme for career practitioners. The study finds that phenomenographic research serves three practical pedagogical purposes: (1) revealing how learners understand certain concepts or phenomena, (2) elucidating how these understandings differ; and (3) identifying critical aspects i…
Effect of temperature on the passive state of Alloy 31 in a LiBr solution: Passivation and Mott-Schottky analysis
2015
The passive behaviour of Alloy 31, a highly-alloyed austenitic stainless steel (UNS N08031), has been investigated in a LiBr heavy brine (700 g/l) at different temperatures using potentiostatic polarisation and Mott-Schottky analysis. Cation vacancies have been found to be the dominant defect in the passive films formed on Alloy 31. An increase in temperature enhanced the generation of cation vacancies at the film/solution interface and raised the steady-state passive current density. The density of defects within the passive film also increased significantly with temperature, making the film more conductive and less protective against localised attacks.