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The MnSn monolayer synthesized recently is a novel two-dimensional ferromagnetic material with a hexagonal lattice, in which three Mn atoms come together to form a trimer, making it remarkably different from other magnetic two-dimensional materials. Most impressively, there occurs a sharp increase of the Curie temperature from 54 to 225 K when the number of layers increases from 1 to 3. However, no quantitative explanation has been reported in previous studies. Herein, by means of the first-principles calculation method and the Monte Carlo method, we demonstrate that strong interlayer ferromagnetic coupling plays an essential role in enhancing its critical temperature, which acts as a magnetic field to stabilize the ferromagnetism in MnSn multilayers. Our work not only explains the sharp increase of the Curie temperature of the MnSn film in experiments but also reveals that the interlayer coupling is a new routine to achieve high-temperature ferromagnetism in two-dimensional materials.

Background: The lateral intersecting margin (dog-ear) was a weak spot of the double stapled technique (DST), We designed "dog-ear" invagination anastomosis (DAIA), which could eliminate the "dog-ear" in laparoscopic anterior resection. Methods: A total of 202 patients underwent elective curative LLAR + DST (n = 143) or LLAR + DAIA (n = 59) were enrolled in the study. Propensity score matching (PSM) was used to minimize the adverse effects. The clinical data between LLAR + DST and LLAR + DAIA was compared. Results: After PSM, 53 pairs of the LLRA + DST and LLRA + DAIA patients were enrolled in the study. The LLRA + DAIA group has a higher level (3.50 ± 1.03 vs. 2.87 ± 1.10, p = 0.01) of the anastomosis than that of the LLRA + DST group. Patients in LLAR + DAIA group have a lower incidence of protecting loop ileostomy compared to LLAR + DST group(20.75% vs. 5.66%, P 0.05). Conclusion Laparoscopic low anterior resection with "dog-ear" invagination anastomosis technique are well-established procedures for patients with low rectal cancer. "Dog-ear" invagination anastomosis technique may reduce the incidence of protecting loop ileostomy and significantly affect LARS score, and demonstrate a positive impact on the quality of life after surgery.

This paper presents a novel pre-trained language models (PLM) compression approach based on the matrix product operator (short as MPO) from quantum many-body physics. It can decompose an original matrix into central tensors (containing the core information) and auxiliary tensors (with only a small proportion of parameters). With the decomposed MPO structure, we propose a novel fine-tuning strategy by only updating the parameters from the auxiliary tensors, and design an optimization algorithm for MPO-based approximation over stacked network architectures. Our approach can be applied to the original or the compressed PLMs in a general way, which derives a lighter network and significantly reduces the parameters to be fine-tuned. Extensive experiments have demonstrated the effectiveness of the proposed approach in model compression, especially the reduction in finetuning parameters (91% reduction on average)., Comment: Accepted by ACL 2021 main conference

With an auxiliary weak external magnetic field, we reexamine the fundamental thermodynamic function, Gibbs free energy $G(T,h)$, to study phase transitions in classical spin lattice models. A cross derivative, i.e., the second-order partial derivative of $G(T,h)$ with respect to both temperature and field, is calculated to precisely locate the critical temperature, which also reveals the nature of a transition. The strategy is efficient and universal, as exemplified by the five-state clock model, two-dimensional (2D) and 3D Ising models, and the $XY$ model, no matter if a transition is trivial or exotic with complex excitations. More importantly, other conjugate pairs could also be integrated into a similar cross derivative if necessary, which would greatly enrich our vision and means to investigate phase transitions both theoretically and experimentally.

We perform the state-of-the-art tensor network simulations directly in the thermodynamic limit to clarify the critical properties of the $q$-state clock model on the square lattice. We determine accurately the two phase transition temperatures through the singularity of the classical analog of the entanglement entropy, and provide extensive numerical evidences to show that both transitions are of the Berezinskii-Kosterlitz-Thouless (BKT) type for $q\ge 5$ and that the low-energy physics of this model is well described by the $\mathbb{Z}_q$-deformed sine-Gordon theory. We also determine the characteristic conformal parameters, especially the compactification radius, that govern the critical properties of the intermediate BKT phase., 5 pages, 5 figures plus supplemental material; accepted for publication in Phys. Rev. E (Rapid Com.), minor typo corrections

Tensor renormalization group (TRG) constitutes an important methodology for accurate simulations of strongly correlated lattice models. Facilitated by the automatic differentiation technique widely used in deep learning, we propose a uniform framework of differentiable TRG ($\partial$TRG) that can be applied to improve various TRG methods, in an automatic fashion. Essentially, $\partial$TRG systematically extends the concept of second renormalization [PRL 103, 160601 (2009)] where the tensor environment is computed recursively in the backward iteration, in the sense that given the forward process of TRG, $\partial$TRG automatically finds the gradient through backpropagation, with which one can deeply "train" the tensor networks. We benchmark $\partial$TRG in solving the square-lattice Ising model, and demonstrate its power by simulating one- and two-dimensional quantum systems at finite temperature. The deep optimization as well as GPU acceleration renders $\partial$TRG manybody simulations with high efficiency and accuracy., 13 pages, 9 figures

The design and exploration of ferromagnetic two-dimensional materials is an important research topic due to their potential applications in spintronic devices. By the first-principles calculations, we examine the structural stability and the electronic properties of transition metal carbonitrides MN4C2 (M = 3d transition metals) and find out that chromium carbonitride CrN4C2 is a ferromagnetic two-dimensional material. CrN4C2 is made up of CrN4 unit and C2 dimer, stacked alternatively to form a planar single-atom-thick sheet. For the Cr 3d electronic states, there is a complete spin splitting between Cr 3d spin-up and spin-down states, leading to a large moment up to 3.76 μB around Cr atoms. The magnetic interaction among Cr atoms can be described by Ising model, and the ferromagnetic couplings are energetically favorable, which indicates that there must be a ferromagnetic phase transition and a ferromagnetic ground state. The Curie temperature of CrN4C2 is evaluated to be 226.6 K in terms of the tensor renormalization group method. With Hubbard U of 3 eV and 5 eV being considered, the Curie temperatures reach up to 331.1 and 283.6 K. Consequently, our results demonstrate that CrN4C2 is a graphene-like two-dimensional material with robust ferromagnetism.

A deep neural network is a parametrization of a multilayer mapping of signals in terms of many alternatively arranged linear and nonlinear transformations. The linear transformations, which are generally used in the fully connected as well as convolutional layers, contain most of the variational parameters that are trained and stored. Compressing a deep neural network to reduce its number of variational parameters but not its prediction power is an important but challenging problem toward the establishment of an optimized scheme in training efficiently these parameters and in lowering the risk of overfitting. Here we show that this problem can be effectively solved by representing linear transformations with matrix product operators (MPOs), which is a tensor network originally proposed in physics to characterize the short-range entanglement in one-dimensional quantum states. We have tested this approach in five typical neural networks, including FC2, LeNet-5, VGG, ResNet, and DenseNet on two widely used data sets, namely, MNIST and CIFAR-10, and found that this MPO representation indeed sets up a faithful and efficient mapping between input and output signals, which can keep or even improve the prediction accuracy with a dramatically reduced number of parameters. Our method greatly simplifies the representations in deep learning, and opens a possible route toward establishing a framework of modern neural networks which might be simpler and cheaper, but more efficient., Comment: 8+9 pages, 3+7 figures, 2+11 tables

The dynamic recrystallization (DRX) process of hot compressed aluminium alloy 7050 was predicted using cellular automaton (CA) combined with topology deformation. The hot deformatation characteristics of aluminium alloy 7050 were investigated by hot uniaxial compression tests in order to obtain the material parameters used in the CA model. The influences of process parameters (strain, strain rate and temperature) on the fraction of DRX and the average recrystallization grain (R-grain) size were investigated and discussed. It is found that larger stain, higher temperature and lower strain rate (less than 0.1 s–1) are beneficial to the increasing fraction of DRX. And the deformation temperature affects the mean R-grain size much more greatly than other parameters. It is also noted that there is a critical strain for the occurrence of DRX which is related to strain rate and temperature. In addition, it is shown that the CA model with topology deformation is able to simulate the microstructural evolution and the flow behavior of aluminium alloy 7050 material under various deformation conditions.

The Chebyshev expansion offers a numerically efficient and easy-implement algorithm for evaluating dynamic correlation functions using matrix product states (MPS). In this approach, each recursively generated Chebyshev vector is approximately represented by an MPS. However, the recurrence relations of Chebyshev polynomials are broken by the approximation, leading to an error which is accumulated with the increase of the order of expansion. Here we propose a reorthonormalization approach to remove this error introduced in the loss of orthogonality of the Chebyshev polynomials. Our approach, as illustrated by comparison with the exact results for the one-dimensional XY and Heisenberg models, improves significantly the accuracy in the calculation of dynamical correlation functions., 9 pages, 8 figures

Using the tensor renormalization group method based on the higher-order singular value decomposition,we have studied the phase transitions of the five-state clock model on the square lattice.The temperature dependence of the specific heat indicates the system has two phase transitions, as verified clearly in the correlation function. By investigating the magnetic susceptibility, we can only obtain the upper critical temperature as Tc2 = 0.9565(7). From the fixed-point tensor, we locate the transition temperatures at Tc1 = 0.9029(1) and Tc2 = 0.9520(1), consistent with the MC and the DMRG results., Comment: 5 pages, 7 figures

An attempt was made to analyze the damage evolution and ductile fracture of incremental forming at the microscopic level. Firstly, an extended Gurson–Tvergaard–Needleman (GTN) model integrating with Hill’48 anisotropic yield criterion was established and numerically implemented by User-defined Material Subroutine (VUMAT) in the commercial finite element software ABAQUS. Then, the VUMAT program was verified via a single element test, and its damage parameters were determined through the combination of the simulation and the experiment of a tensile test. Afterwards, based on the extended GTN model, a finite element model of incremental forming was established and experimentally verified. And the influence of different values of two damage parameters, the volume fraction of void nucleating particles f N and the mean plastic strain value when voids nucleate e N, on the damage evolution of incremental forming was explored. It shows that there is almost no connection between the microscopic equivalent strain $$ {\overline{\varepsilon}}_{\mathrm{m}}^{\mathrm{pl}} $$ and the values of f N and e N. However, the maximum value of void volume fraction will increase significantly with the increase of f N or with the decrease of e N. Finally, void volume fraction was proved to be an effective index to predict crack occurrence of incremental forming.

In order to support characters of data acquisition system of smart grid, such as scalable and plug and play, one configurable node of sensor network was proposed. The number of protocol standard, the number of interface of each protocol standard, the number of senor of each interface and the number of byte of each sensor can be configured in this node. All these parameters can be configured according to the specific application of smart grid and then achieve the best balance between cost and performance. One real model was implemented by VHDL and the number of protocol standard, the number of interface of each protocol standard, the number of sensor of each interface, the number of byte of each sensor can be configured in the range from 1 to 8. The correctness and validity of this real model were confirmed by simulation results of configurable level and one application instance.

In the tensor-network framework, the expectation values of two-dimensional quantum states are evaluated by contracting a double-layer tensor network constructed from initial and final tensor-network states. The computational cost of carrying out this contraction is generally very high, which limits the largest bond dimension of tensor-network states that can be accurately studied to a relatively small value. We propose an optimized contraction scheme to solve this problem by mapping the double-layer tensor network onto an intersected single-layer tensor network. This reduces greatly the bond dimensions of local tensors to be contracted and improves dramatically the efficiency and accuracy of the evaluation of expectation values of tensor-network states. It almost doubles the largest bond dimension of tensor-network states whose physical properties can be efficiently and reliably calculated, and it extends significantly the application scope of tensor-network methods., 7 pages, 6 figures, accepted version for Phys. Rev. B. The title is changed for easier understanding

We investigate the critical behavior and the duality property of the ferromagnetic $q$-state clock model on the square lattice based on the tensor-network formalism. From the entanglement spectra of local tensors defined in the original and dual lattices, we obtain the exact self-dual points for the model with $q \leq 5 $ and approximate self-dual points for $q \geq 6$. We calculate accurately the lower and upper critical temperatures for the six-state clock model from the fixed-point tensors determined using the higher-order tensor renormalization group method and compare with other numerical results., Comment: 5 pages, 4 figures

Frustrated quantum magnetism has moved to the forefront of physics research, posing fundamental questions concerning quantum disordered states, entanglement, topology and the nature of the quantum wavefunction. The defining problem in the field is one of the simplest, the ground state of the nearest-neighbour $S = 1/2$ antiferromagnetic Heisenberg model on the kagome lattice, but has defied all theoretical and numerical methods employed to date. We apply the formalism of tensor-network states (TNS), specifically the method of projected entangled simplex states (PESS), whose combination of a correct accounting for multipartite entanglement and infinite system size provides qualitatively new insight. By studying the ground-state energy, the staggered magnetization we find at all finite tensor bond dimensions and the effects of a second-neighbour coupling, we demonstrate that the ground state is a gapless spin liquid. We discuss the comparison with other numerical studies and the physical interpretation of the gapless ground state., Comment: 8 pages, 4 figures, revised version accepted for publication in PRL

We propose a generalized Lanczos method to generate the many-body basis states of quantum lattice models using tensor-network states (TNS). The ground-state wave function is represented as a linear superposition composed from a set of TNS generated by Lanczos iteration. This method improves significantly both the accuracy and the efficiency of the tensor-network algorithm and allows the ground state to be determined accurately using TNS with very small virtual bond dimensions. This state contains significantly more entanglement than each individual TNS, reproducing correctly the logarithmic size dependence of the entanglement entropy in a critical system. The method can be generalized to non-Hamiltonian systems and to the calculation of low-lying excited states, dynamical correlation functions, and other physical properties of strongly correlated systems., 5 pages, 5 figures

With the rapid development of the smart grid in our country, we need many 10kV smart switches which can protect the safety of the line and complete the reasonable scheduling of the electricity load. In order to realize the reliable power supply for 10kV smart switch, power supply system based on photovoltaic cell technology is designed. In this paper, firstly, we have a brief introduction about the 10kV smart switch. Secondly, composing and principle of the power supply system is introduced. And then, principle of the energy harvesting converter main circuit is analyzed in detail. Then, the MPPT method of the photovoltaic cell based on impedance matching is studied. Test show, the power supply system is suitable for 10kV smart switch measurement and control.

A solution-processable interfacial bilayer is found to be able to significantly increase a short-circuit current and thus the overall performance of bulk heterojunction organic photovoltaic cells. The interfacial bilayer is comprised of surface-modified single-layer graphene oxide and a donor polymer. The use of the interfacial bilayer can minimize exciton quenching and inverse current and does not alter the energy level of photovoltaic devices, which is also applicable to other organic optoelectronic diode devices.

We compare two calculations of the particle density in the superfluid phase of the O(2) model with a chemical potential μ in 1+1 dimensions. The first relies on exact blocking formulas from the Tensor Renormalization Group (TRG) formulation of the transfer matrix. The second is a worm algorithm. We show that the particle number distributions obtained with the two methods agree well. We use the TRG method to calculate the thermal entropy and the entanglement entropy. We describe the particle density, the two entropies and the topology of the world lines as we increase μ to go across the superfluid phase between the first two Mott insulating phases. For a sufficiently large temporal size, this process reveals an interesting fine structure: the average particle number and the winding number of most of the world lines in the Euclidean time direction increase by one unit at a time. At each step, the thermal entropy develops a peak and the entanglement entropy increases until we reach half-filling and then decreases in a way that approximately mirrors the ascent. This suggests an approximate fermionic picture.

With the development of smart grid construction, a large number of intelligent electrical equipment has been applied. In order to facilitate the onsite FTU data acquisition, use S3C6410 with ARM11 kernel and Windows CE embedded system as platform to develop and design wireless intelligent information acquisition system. After the hardware platform and embedded system are completed, add wireless module driver, develop information frame format of communication protocol, and according to the application software requirements, design and develop FTU wireless communication applications. After experimental testing, FTU wireless communications is fulfilled between the portable equipment and 10KV power lines; then acquires and process the returning data. This article provides feasibility program for the FTU field local test.

In order to explore high strength organic electrotransporting electroluminescent (EL) materials, twelve new pyrazole oxadiazole compounds containing the benzothiazole or benzene group in the 1 position of pyrazole, the aromatic group in the 3 position of pyrazole and the formacyl group in the 4 position of pyrazole were designed and synthesized. A new method of synthesizing 1,3,4-oxadiazole compound was described. Their structures were characterized by IR, MS, 1H NMR spectra and elemental analysis. The fluorescence properties were measured by fluorometry. The results showed that the target compounds had good fluorescence and λem ranged from 410nm to 450 nm and fluorescence quantum yields up to 0.69.

We perform a systematic study of the antiferromagnetic Heisenberg model on the Husimi lattice using numerical tensor-network methods based on Projected Entangled Simplex States (PESS). The nature of the ground state varies strongly with the spin quantum number, $S$. For $S = 1/2$, it is an algebraic (gapless) quantum spin liquid. For $S = 1$, it is a gapped, non-magnetic state with spontaneous breaking of triangle symmetry (a trimerized simplex-solid state). For $S = 2$, it is a simplex-solid state with a spin gap and no symmetry-breaking; both integer-spin simplex-solid states are characterized by specific degeneracies in the entanglement spectrum. For $S = 3/2$, and indeed for all spin values $S \ge 5/2$, the ground states have $120$-degree antiferromagnetic order. In a finite magnetic field, we find that, irrespective of the value of $S$, there is always a plateau in the magnetization at $m = 1/3$., 18 pages, 25 figures;minor changes, refs updated

We develop coarse-graining tensor renormalization group algorithms to compute physical properties of two-dimensional lattice models on finite periodic lattices. Two different coarse-graining strategies, one based on the tensor renormalization group and the other based on the higher-order tensor renormalization group, are introduced. In order to optimize the tensor-network model globally, a sweeping scheme is proposed to account for the renormalization effect from the environment tensors under the framework of second renormalization group. We demonstrate the algorithms by the classical Ising model on the square lattice and the Kitaev model on the honeycomb lattice, and show that the finite-size algorithms achieve substantially more accurate results than the corresponding infinite-size ones., 14 pages, 14 figures

The cytochrome P450 (CYP) is a superfamily of enzymes with oxidative function responsible for the metabolism of xenobiotics especially drug metabolism. CYP3A4, an extensive studied CYP isoform, plays crucial role in the metabolism of structurally diverse drugs. Furthermore, the drug-drug interaction resulted from the inhibition of CYP3A4 activity is of extreme importance for the treatment of disease and the development of new drug. In this study, using the method of the support vector machine (SVM) and three descriptors selected from the 153 descriptors we construct the models that can predict accurately the inhibitory effect of a compound on the activity of CYP3A4. By optimizing the parameters related to SVM, the cross validation correlation efficient of the model can achieve 0.71, which is higher than those of other models obtained using Artifical Neutral Network (ANN) and Partial least square (PLS) methods to our knowledge, and thus our model can present the important application in assessment of the potential toxicity of a drug as well as prediction of drug-drug interactions.

Introduction: Lifelong premature ejaculation (LPE) is characterized by persistently shorter intravaginal ejaculation latency time (IELT) than found acceptable by the patient or his partner. It has been postulated to be a neurobiological dysfunction with genetic vulnerability and is related to disturbances of central serotonin (5-hydroxytryptamine, 5-HT) neurotransmission and 5-HT receptor function. Aim: To investigate the relationship between the C–759T and G–697C polymorphisms of the 5-HT2C receptor and LPE. Methods: A prospective study was conducted in 106 Han Chinese men with LPE, characterized by IELT of less than 1 min, and 84 healthy controls with IELT of more than 3 min. All subjects were genotyped for the C–759T and G–697C polymorphisms located in the promoter region of the 5-HT2C receptor. The frequencies of genotypes and single nucleotide mutations were compared between the two groups. Results: Three genotypes were detected both in the men with LPE and in the control group: –759C/–697G, –759T/–697C, and –759C/ –697C. Genotype –759T/–697G was not detected. The frequency of genotype –759T/–697C was higher in patients with LPE than in the control group (30.2 vs. 11.9%, p < 0.05), whereas the frequency of genotype –759C/–697G was lower in patients with LPE than in the control group (66.0 vs. 83.3%, p < 0.05). No difference was found for genotype –759C/ –697C between the two groups. Mutations at –759T and –697C were more frequent in patients than in the control group (–759T: 30.2 vs. 13.3%, p < 0.05; –697C: 30.4 vs. 16.7%, p < 0.05, respectively). Conclusions: Our findings indicated that polymorphisms in the 5-HT2C receptor gene are associated with LPE, and men who carry the –759T or –697C genotype have increased odds of premature ejaculation. Further investigation in this field is necessary.

Dysfunction in α7 nicotinic acetylcholine receptor (nAChR), a member of the Cys-loop ligand-gated ion channel superfamily, is responsible for attentional and cognitive deficits in Alzheimers disease (AD). To provide useful information for finding drug candidates for the treatment of AD, a study was carried out according to the following procedures. (1) DMXBA, a partial agonist of the α7 nAChR, was used as a template molecule. (2) To reduce the number of compounds to be considered, the similarity search and flexible alignment were conducted to exclude those molecules which did not match the template. (3) The molecules thus obtained were docked to α7 nAChR. (4) To gain more structural information, the molecular dynamics (MD) simulations were carried out for 9 most favorable agonists obtained by the aforementioned docking studies. (5) By analyzing the hydrogen bond interaction and hydrophobic/hydrophilic interaction, the following seven compounds were singled out as possible drug candidates for AD therapy: gx-50, gx-51, gx-52, gx-180, open3d-99008, open3d-51265, open3d-60247.

We discuss the Tensor Renormalization Group (TRG) method for the O(2) model with a chemical potential in 1+1 dimensions with emphasis on near gapless/conformal situations. We emphasize the role played by the late Leo Kadanoff in the development of this theoretical framework. We describe the entanglement entropy in the superfluid phase (see arXiv:1507.01471 for details). We present recent progress on optimized truncation methods., Comment: Submitted as PoS(LATTICE 2015)285. Talk given by Yannick Meurice at the The 33rd International Symposium on Lattice Field Theory, 14 -18 July 2015, Kobe, Japan. Latex with 7 pages and 9 figures

We propose an eigen-operator scheme to study the lattice model of interacting spinless fermions at half filling and show that this model possesses a hidden form of reflection positivity in its Majorana fermion representation. Based on this observation, we prove rigourously that the ground state of this model is either unique or doubly degenerate if the lattice size $N$ is even, and is always doubly degenerate if $N$ is odd. This proof holds in all dimensions with arbitrary lattice structures.

The Potts model plays an essential role in classical statistical mechanics, illustrating many fundamental phenomena. One example is the existence of partially long-range-ordered states, in which some degrees of freedom remain disordered. This situation may arise from frustration of the interactions, but also from an irregular but unfrustrated lattice structure. We study partial long-range order in a range of antiferromagnetic $q$-state Potts models on different two-dimensional lattices and for all relevant values of $q$. We exploit the power of tensor-based numerical methods to evaluate the partition function of these models and hence to extract the key thermodynamic properties -- entropy, specific heat, magnetization, and susceptibility -- giving deep insight into the phase transitions and ordered states of each system. Our calculations reveal a range of phenomena related to partial ordering, including different types of entropy-driven phase transition, the role of lattice irregularity, very large values of the critical $q_c$, and double phase transitions., 23 pages, 27 figures

We connect explicitly the classical $O(2)$ model in 1+1 dimensions, a model sharing important features with $U(1)$ lattice gauge theory, to physical models potentially implementable on optical lattices and evolving at physical time. Using the tensor renormalization group formulation, we take the time continuum limit and check that finite dimensional projections used in recent proposals for quantum simulators provide controllable approximations of the original model. We propose two-species Bose-Hubbard models corresponding to these finite dimensional projections at strong coupling and discuss their possible implementations on optical lattices using a $^{87}$Rb and $^{41}$K Bose-Bose mixture., 7 pages, 6 figures, uses revtex, new material and one author added, as to appear in Phys. Rev. A

We introduce a slave-fermion formulation in which to study the charge dynamics of the half-filled Hubbard model on the square lattice. In this description, the charge degrees of freedom are represented by fermionic holons and doublons and the Mott-insulating characteristics of the ground state are the consequence of holon–doublon bound-state formation. The bosonic spin degrees of freedom are described by the antiferromagnetic Heisenberg model, yielding long-ranged (Neel) magnetic order at zero temperature. Within this framework and in the self-consistent Born approximation, we perform systematic calculations of the average double occupancy, the electronic density of states, the spectral function and the optical conductivity. Qualitatively, our method reproduces the lower and upper Hubbard bands, the spectral-weight transfer into a coherent quasiparticle band at their lower edges and the renormalisation of the Mott gap, which is associated with holon–doublon binding, due to the interactions of both quasiparticle species with the magnons. The zeros of the Green function at the chemical potential give the Luttinger volume, the poles of the self-energy reflect the underlying quasiparticle dispersion with a spin-renormalised hopping parameter and the optical gap is directly related to the Mott gap. Quantitatively, the square-lattice Hubbard model is one of the best-characterised problems in correlated condensed matter and many numerical calculations, all with different strengths and weaknesses, exist with which to benchmark our approach. From the semi-quantitative accuracy of our results for all but the weakest interaction strengths, we conclude that a self-consistent treatment of the spin-fluctuation effects on the charge degrees of freedom captures all the essential physics of the antiferromagnetic Mott–Hubbard insulator. We remark in addition that an analytical approximation with these properties serves a vital function in developing a full understanding of the fundamental physics of the Mott state, both in the antiferromagnetic insulator and at finite temperatures and dopings.

Using the tensor renormalization group method based on the higher-order singular value decom- position, we have studied the thermodynamic properties of the continuous XY model on the square lattice. The temperature dependence of the free energy, the internal energy and the specific heat agree with the Monte Carlo calculations. From the field dependence of the magnetic susceptibility, we find the Kosterlitz-Thouless transition temperature to be 0.8921 \pm 0.0019, consistent with the Monte Carlo as well as the high temperature series expansion results. At the transition temperature, the critical exponent \delta is estimated as 14.5, close to the analytic value by Kosterlitz., Comment: 5 pages, 6 figures

The surface of ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}{\mathrm{MnO}}_{3}$ (LCMO) films with $x\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.1$, $0.33$, $0.5$, and $0.66$ has been studied; a highly ordered grain pattern induced by strain is observed in films with $x\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.5$ and $0.66$. The strain is identified to result from thermal expansion mismatch between substrate and film, and thermal expansion anomaly may exist at a high temperature induced by possible phase transition in LCMO with $x\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.5$ and $0.66$. Such phenomenon is arresting on film growth and understanding colossal magnetoresistance materials as well as providing a new way to make ordered structures for application.

Using the example of the two-dimensional (2D) Ising model, we show that in contrast to what can be done in configuration space, the tensor renormalization group (TRG) formulation allows one to write exact, compact, and manifestly local blocking formulas and exact coarse grained expressions for the partition function. We argue that similar results should hold for most models studied by lattice gauge theorists. We provide exact blocking formulas for several 2D spin models (the O(2) and O(3) sigma models and the SU(2) principal chiral model) and for the 3D gauge theories with groups Z_2, U(1) and SU(2). We briefly discuss generalizations to other groups, higher dimensions and practical implementations., Comment: 12 pages, 10 figures

We propose a new class of tensor-network states, which we name projected entangled simplex states (PESS), for studying the ground-state properties of quantum lattice models. These states extend the pair-correlation basis of projected entangled pair states (PEPS) to a simplex. PESS are an exact representation of the simplex solid states and provide an efficient trial wave function that satisfies the area law of entanglement entropy. We introduce a simple update method for evaluating the PESS wave function based on imaginary-time evolution and the higher-order singular-value decomposition of tensors. By applying this method to the spin-1/2 antiferromagnetic Heisenberg model on the kagome lattice, we obtain accurate and systematic results for the ground-state energy, which approach the lowest upper bounds yet estimated for this quantity., 12 pages, 8 figures

Power line communication (PLC) technology is an important communication method widely used in Smart grid. Noise seriously affects the reliability of power line communication. In this paper, channel noises of power line and attenuation of the distribution transformer in high frequency are measured and the noise characteristics are analyzed. This paper first puts forward considering the Low-Voltage (LV) feedback noise coupling through distribution transformer in Medium-voltage (MV) side. Considering the feedback noise, this paper gives an overview of the modeling of distribution transformers in high frequency and deals with the research methods of high frequency noise propagation characteristic through the transformer.

Orthogonal Frequency Division Multiplexing (OFDM) is a promising technology for combating the frequency selective fading, multipath propagation, and narrowband interference in power line communication. However, OFDM systems are extremely sensitive to synchronization deviation. Slight synchronization deviation can affect the performance of OFDM systems. This paper presents a design and implementation synchronization algorithm based on constant amplitude zero auto-correlation (CAZAC) for power line communication. Matlab simulation prove that, with less computation, the proposed algorithm can complete symbol timing synchronization and frequency offset synchronization well and the performance of OFDM synchronization in power line communication is significantly improved.

We explore the Potts model on the generalized decorated square lattice, with both nearest (J1) and next-neighbor (J2) interactions. Using the tensor renormalization-group method augmented by higher-order singular value decompositions, we calculate the spontaneous magnetization of the Potts model with q = 2, 3, and 4. The results for q = 2 allow us to benchmark our numerics using the exact solution. For q = 3, we find a highly degenerate ground state with partial order on a single sublattice, but with vanishing entropy per site, and we obtain the phase diagram as a function of the ratio J2=J1. There is no finite-temperature transition for the q = 4 case when J1 = J2, but the magnetic susceptibility diverges as the temperature goes to zero, showing that the model is critical at T = 0., Comment: 5 pages, 6 figures

We consider the sign problem for classical spin models at complex $\beta =1/g_0^2$ on $L\times L$ lattices. We show that the tensor renormalization group method allows reliable calculations for larger Im$\beta$ than the reweighting Monte Carlo method. For the Ising model with complex $\beta$ we compare our results with the exact Onsager-Kaufman solution at finite volume. The Fisher zeros can be determined precisely with the TRG method. We check the convergence of the TRG method for the O(2) model on $L\times L$ lattices when the number of states $D_s$ increases. We show that the finite size scaling of the calculated Fisher zeros agrees very well with the Kosterlitz-Thouless transition assumption and predict the locations for larger volume. The location of these zeros agree with Monte Carlo reweighting calculation for small volume. The application of the method for the O(2) model with a chemical potential is briefly discussed., Comment: 8 pages, 9 figures

We propose a modified spin-wave theory to study the 1/3 magnetization plateau of the antiferromagnetic Heisenberg model on the kagome lattice. By the self-consistent inclusion of quantum corrections, the 1/3 plateau is stabilized over a broad range of magnetic fields for all spin quantum numbers, S. The values of the critical magnetic fields and the widths of the magnetization plateaus are fully consistent with recent numerical results from exact diagonalization and infinite projected entangled paired states., Comment: 5 pages, 4 figures, accepted in Chinese Physics Letters