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51.
We study extremality in various sets of states that have positive partial transposes. One of the tools we use for this purpose is the recently formulated criterion allowing to judge if a given state is extremal in the set of PPT states. First we investigate qubit-ququart states and show that the only candidates for extremal PPT entangled states (PPTES) have ranks of the state and its partial transposition (5, 5) or (5, 6) (equivalently (6, 5)). Then, examples of extremal states of (5, 5) type and the so-called edge states of type (5, 6) are provided. We also make an attempt to explore the set of PPT states with ranks (5, 6). Finally, we discuss what are the possible configurations of ranks of density matrices and their respective partial transposition in general three-qubit and four-qubit symmetric states for which there may exist extremal entangled PPT states. For instance in the first case we show that the only possibilities are (4, 4, 4) and (4, 4, 5). 相似文献
52.
53.
A. Grabowski N. Kruszewska R. A. Kosiński 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,66(1):107-113
We study properties of five different social systems: (i) internet society of friends consisting of over 106 people, (ii) social network consisting of 3 × 104 individuals, who interact in a large virtual world of Massive Multiplayer Online Role Playing Games (MMORPGs), (iii) over
106 users of music community website, (iv) over 5 × 106 users of gamers community server and (v) over 0.25 × 106 users of books admirer website. Individuals included in large social network form an Internet community and organize themselves
in groups of different sizes. The destiny of those systems, as well as the method of creating of new connections, are different,
however we found that the properties of these networks are very similar.
We have found that the network components size distribution follow the power-law scaling form. In all five systems we have
found interesting scaling laws concerning human dynamics. Our research has shown how long people are interested in a single
task, how much time they devote to it and how fast they are making friends. It is surprising that the time evolution of an
individual connectivity is very similar in each system. 相似文献
54.
Prof. Sławomir J. Grabowski 《Chemphyschem》2019,20(4):565-574
ωB97XD/aug-cc-pVTZ calculations were performed for complexes of dihydrogen, cyclopropane, cyclobutane and cyclopentane, with simple proton donating species such as hydrogen fluoride, hydrogen chloride, water, hydrogen cyanide and acetylene. Numerous dependencies between geometrical, energetic and topological parameters of complexes considered were found, since various theoretical approaches were applied: Quantum Theory of ‘Atoms in Molecules’ (QTAIM), Natural Bond Orbital (NBO) method and energy decomposition analysis (EDA). It was confirmed that complexes of dihydrogen and cyclopropane are linked through the A−H…σ interactions that may be classified as hydrogen bonds. In the case of complexes of cyclobutane such hydrogen bonds are rather weak. Other type and also weak A−H…C hydrogen bonds are formed for complexes with cyclopentane. 相似文献
55.
Accurate Kohn–Sham ionization potentials from scaled‐opposite‐spin second‐order optimized effective potential methods 下载免费PDF全文
Szymon Śmiga Fabio Della Sala Adam Buksztel Ireneusz Grabowski Eduardo Fabiano 《Journal of computational chemistry》2016,37(22):2081-2090
One important property of Kohn–Sham (KS) density functional theory is the exact equality of the energy of the highest occupied KS orbital (HOMO) with the negative ionization potential of the system. This exact feature is out of reach for standard density‐dependent semilocal functionals. Conversely, accurate results can be obtained using orbital‐dependent functionals in the optimized effective potential (OEP) approach. In this article, we investigate the performance, in this context, of some advanced OEP methods, with special emphasis on the recently proposed scaled‐opposite‐spin OEP functional. Moreover, we analyze the impact of the so‐called HOMO condition on the final quality of the HOMO energy. Results are compared to reference data obtained at the CCSD(T) level of theory. © 2016 Wiley Periodicals, Inc. 相似文献
56.
Patil S Matei G Grabowski CA Hoffmann PM Mukhopadhyay A 《Langmuir : the ACS journal of surfaces and colloids》2007,23(9):4988-4992
We have studied the dynamic structure of thin (approximately a few nanometers) liquid films of a nearly spherical, nonpolar molecule tetrakis(2-ethylhexoxy)silane (TEHOS) by using a combination of atomic force microscopy (AFM) and fluorescence correlation spectroscopy (FCS). Ultra-sensitive interferometer-based AFM was used to determine the stiffness (force gradient) and the damping coefficient of the liquid film. The experiments show oscillations in the damping coefficient with a period of approximately 1 nm, which is consistent with the molecular dimension of TEHOS as well as previous X-ray reflectivity measurements. Additionally, we performed FCS experiments for direct determination of the molecular dynamics within the liquid film. From the fluctuation autocorrelation curve, we measured the translational diffusion of the probe molecule embedded within the fluid film formed on a solid substrate. The autocorrelation function was best fitted with two components, which indicate that the dynamics are heterogeneous in nature. However, the heterogeneity is not as pronounced as had been previously observed for molecularly thin liquid films sandwiched between two solid substrates. 相似文献
57.
Andrzej Grabowski 《Physica A》2009,388(6):961-966
The model of opinion formation in human population based on social impact theory is investigated numerically. On the basis of a database received from the on-line game server, we examine the structure of social network and human dynamics. We calculate the activity of individuals, i.e. the relative time devoted daily to interactions with others in the artificial society. We study the influence of correlation between the activity of an individual and its connectivity on the process of opinion formation. We find that such correlations have a significant influence on the temperature of the phase transition and the effect of the mass media, modeled as an external stimulation acting on the social network. 相似文献
58.
Average-optimal string matching 总被引:2,自引:0,他引:2
The exact string matching problem is to find the occurrences of a pattern of length m from a text of length n symbols. We develop a novel and unorthodox filtering technique for this problem. Our method is based on transforming the problem into multiple matching of carefully chosen pattern subsequences. While this is seemingly more difficult than the original problem, we show that the idea leads to very simple algorithms that are optimal on average. We then show how our basic method can be used to solve multiple string matching as well as several approximate matching problems in average optimal time. The general method can be applied to many existing string matching algorithms. Our experimental results show that the algorithms perform very well in practice. 相似文献
59.
Reaction of pyranulose 6 with styrenes 12c or 13 and Et3N in CH2Cl2 at 25 °C afforded the [5+2] cycloadducts 14c and 15, which were hydrolyzed to give the natural products 1 and descurainin (2) in 24 and 27% overall yield, respectively. Heating pyranulose 6 with cinnamate ester 21 in the presence of 2,6-di-t-butylpyridine in CH3CN at 175 °C afforded the [5+2] cycloadduct, which was hydrolyzed to give cartorimine (3) in 13% yield. 相似文献
60.
José Manoel Balthazar Dailhane Grabowski Bassinello Angelo Marcelo Tusset Átila Madureira Bueno Bento Rodrigues de Pontes Junior 《Meccanica》2014,49(8):1859-1867
The electromechanical transducer considered in this work is composed of a mechanical oscillator linked to an electronic circuit. Simulations results have determined that for some combination of parameters the electromechanical system is subject to chaotic motion with resonant transient behavior, and after the resonant transient the mechanical system (MS) synchronizes with the electrical system (ES). In order to improve the transient response, avoiding both the chaotic and resonant behaviors, a nonlinear control system is designed, a feedback control strategy is used to drive the system into the desired periodic orbit, and a nonlinear feedforward strategy is used to keep the system into the periodic orbit, obtained by the Fourier series. Two control techniques are used and compared, namely: the state dependent Ricatti equation and the optimal linear feedback control. Numerical simulations results are shown in order to compare the results, considering parametric uncertainties. Additionally, the energy transfer “pumping” between the ES and the MS is also analysed. 相似文献