On traceable iterated line graph and hamiltonian path index

Xiong and Liu[21]gave a characterization of the graphs G for which the n-iterated line graph L^(n)(G)is hamiltonian,for n≥2.In this paper,we study the existence of a hamiltonian path in L^(n)(G),and give a characterization of G for which L^(n)(G)has a hamiltonian path.As applications,we use this characterization to give several upper bounds on the hamiltonian path index of a graph.

Hamiltonian system for the inhomogeneous plane elasticity of dodecagonal quasicrystal plates and its analytical solutions

A Hamiltonian system is derived for the plane elasticity problem of two-dimensional dodecagonal quasicrystals by introducing the simple state function. By using symplectic elasticity approach, the analytic solutions of the phonon and phason displacements are obtained further for the quasicrystal plates. In addition, the effectiveness of the approach is verified by comparison with the data of the finite integral transformation method.

Universal Machine Learning Kohn–Sham Hamiltonian for Materials

While density functional theory(DFT)serves as a prevalent computational approach in electronic structure calculations,its computational demands and scalability limitations persist.Recently,leveraging neural networks to parameterize the Kohn-Sham DFT Hamiltonian has emerged as a promising avenue for accelerating electronic structure computations.Despite advancements,challenges such as the necessity for computing extensive DFT training data to explore each new system and the complexity of establishing accurate machine learning models for multi-elemental materials still exist.Addressing these hurdles,this study introduces a universal electronic Hamiltonian model trained on Hamiltonian matrices obtained from first-principles DFT calculations of nearly all crystal structures on the Materials Project.We demonstrate its generality in predicting electronic structures across the whole periodic table,including complex multi-elemental systems,solid-state electrolytes,Moir´e twisted bilayer heterostructure,and metal-organic frameworks.Moreover,we utilize the universal model to conduct high-throughput calculations of electronic structures for crystals in GNoME datasets,identifying 3940 crystals with direct band gaps and 5109 crystals with flat bands.By offering a reliable efficient framework for computing electronic properties,this universal Hamiltonian model lays the groundwork for advancements in diverse fields,such as easily providing a huge data set of electronic structures and also making the materials design across the whole periodic table possible.

An Eight Component Integrable Hamiltonian Hierarchy from a Reduced Seventh-Order Matrix Spectral Problem

We present an eight component integrable Hamiltonian hierarchy, based on a reduced seventh order matrix spectral problem, with the aim of aiding the study and classification of multicomponent integrable models and their underlying mathematical structures. The zero-curvature formulation is the tool to construct a recursion operator from the spatial matrix problem. The second and third set of integrable equations present integrable nonlinear Schrödinger and modified Korteweg-de Vries type equations, respectively. The trace identity is used to construct Hamiltonian structures, and the first three Hamiltonian functionals so generated are computed.

分数阶Hamiltonian系统的可解性

研究一类分数阶Hamiltonian系统解的存在性.考虑含有参数的势函数W(t,u)满足新的超线性和次线性组合条件W(t,u)=W_(1)(t,u)+μW_(2)(t,u),μ>0.当|u|→∞时,W_(1)(t,u)满足更一般的超线性增长条件,代替Ambrosetti-Rabinowitz条件;W_(2)(t,u)满足更一般的次线性增长条件.这部分需要建立新的紧嵌入定理,用于验证序列的紧性.利用临界点理论,得到上述系统2个解存在结果.

Variational Quantum Eigensolver with Mutual Variance-Hamiltonian Optimization

The zero-energy variance principle can be exploited in variational quantum eigensolvers for solving general eigenstates but its capacity for obtaining a specified eigenstate,such as ground state,is limited as all eigenstates are of zero energy variance.We propose a variance-based variational quantum eigensolver for solving the ground state by searching in an enlarged space of wavefunction and Hamiltonian.With a mutual variance-Hamiltonian optimization procedure,the Hamiltonian is iteratively updated to guild the state towards to the ground state of the target Hamiltonian by minimizing the energy variance in each iteration.We demonstrate the performance and properties of the algorithm with numeral simulations.Our work suggests an avenue for utilizing guided Hamiltonian in hybrid quantum-classical algorithms.

Effective Bi-Layer Model Hamiltonian and Density-Matrix Renormalization Group Study for the High-TcSuperconductivity in La_(3)Ni_(2)O_(7) under High Pressure

High-T_(c)superconductivity with possible T_(c)≈80 K has been reported in the single crystal of La_(3)Ni_(2)O_(7)under high pressure.Based on the electronic structure given by the density functional theory calculations,we propose an effective bi-layer model Hamiltonian including both 3d_(z)^(2)and 3d_((x)^(2)-(y)^(2))orbital electrons of the nickel cations.The main feature of the model is that the 3d_(z)^(2)electrons form inter-layerσ-bonding and anti-bonding bands via the apical oxygen anions between the two layers,while the 3d_((x)^(2)-(y)^(2))electrons hybridize with the 3d_(z)^(2)electrons within each NiO_(2)plane.The chemical potential difference of these two orbital electrons ensures that the 3d_(z)^(2)orbitals are close to half-filling and the 3d_((x)^(2)-(y)^(2))orbitals are near quarter-filling.The strong on-site Hubbard repulsion of the 3d_(z)^(2)orbital electrons gives rise to an effective inter-layer antiferromagnetic spin super-exchange J.Applying pressure can self dope holes on the 3d_(z)^(2)orbitals with the same amount of electrons doped on the 3d_((x)^(2)-(y)^(2))orbitals.By performing numerical density-matrix renormalization group calculations on a minimum setup and focusing on the limit of large J and small doping of 3d_(z)^(2)orbitals,we find the superconducting instability on both the 3d_(z)^(2)and3d_((x)^(2)-(y)^(2))orbitals by calculating the equal-time spin singlet pair–pair correlation function.Our numerical results may provide useful insights in the high-T_(c)superconductivity in single crystal La_(3)Ni_(2)O_(7)under high pressure.

HAMILTON-JACOBI EQUATIONS FOR A REGULAR CONTROLLED HAMILTONIAN SYSTEM AND ITS REDUCED SYSTEMS

In this paper,we give the geometric constraint conditions of a canonical symplectic form and regular reduced symplectic forms for the dynamical vector fields of a regular controlled Hamiltonian(RCH)system and its regular reduced systems,which are called the Type I and Type II Hamilton-Jacobi equations.First,we prove two types of Hamilton-Jacobi theorems for an RCH system on the cotangent bundle of a configuration manifold by using the canonical symplectic form and its dynamical vector field.Second,we generalize the above results for a regular reducible RCH system with symmetry and a momentum map,and derive precisely two types of Hamilton-Jacobi equations for the regular point reduced RCH system and the regular orbit reduced RCH system.Third,we prove that the RCH-equivalence for the RCH system,and the RpCH-equivalence and RoCH-equivalence for the regular reducible RCH systems with symmetries,leave the solutions of corresponding Hamilton-Jacobi equations invariant.Finally,as an application of the theoretical results,we show the Type I and Type II Hamilton-Jacobi equations for the Rp-reduced controlled rigid body-rotor system and the Rp-reduced controlled heavy top-rotor system on the generalizations of the rotation group SO(3)and the Euclidean group SE(3),respectively.This work reveals the deeply internal relationships of the geometrical structures of phase spaces,the dynamical vector fields and the controls of the RCH system.

完全正则m-元树的Hamiltonian色数与最小Hamiltonian着色

对一个n阶连通图G,G的Hamiltonian着色(以下简称G的H着色)定义为从G的顶点集V(G)到正整数集N(称为颜色集)的一个映射c,且对G的任意2个不同顶点u和v,满足|c(u)-c(v)|+D(u,v)≥n-1,其中D(u,v)表示G中u到v的最长路径的长度。对G的一个H着色c,将Max{c(u)|u∈V(G)}称为c的值,记作hc(c)。将Min{hc(c)|c是G的H着色}称为G的Hamiltonian色数(以下简称G的H色数),记作hc(G)。如果G的一个H着色c满足hc(c)=hc(G),则称c为G的一个最小H着色。本次研究得到了完全正则m-元树的H色数的确切值,并给出了其最小H着色。

Explicit K-symplectic methods for nonseparable non-canonical Hamiltonian systems

We propose efficient numerical methods for nonseparable non-canonical Hamiltonian systems which are explicit,K-symplectic in the extended phase space with long time energy conservation properties. They are based on extending the original phase space to several copies of the phase space and imposing a mechanical restraint on the copies of the phase space. Explicit K-symplectic methods are constructed for two non-canonical Hamiltonian systems. Numerical tests show that the proposed methods exhibit good numerical performance in preserving the phase orbit and the energy of the system over long time, whereas higher order Runge–Kutta methods do not preserve these properties. Numerical tests also show that the K-symplectic methods exhibit better efficiency than that of the same order implicit symplectic, explicit and implicit symplectic methods for the original nonseparable non-canonical systems. On the other hand, the fourth order K-symplectic method is more efficient than the fourth order Yoshida’s method, the optimized partitioned Runge–Kutta and Runge–Kutta–Nystr ¨om explicit K-symplectic methods for the extended phase space Hamiltonians, but less efficient than the the optimized partitioned Runge–Kutta and Runge–Kutta–Nystr ¨om extended phase space symplectic-like methods with the midpoint permutation.

HOMOCLINIC SOLUTIONS NEAR THE ORIGIN FOR A CLASS OF FIRST ORDER HAMILTONIAN SYSTEMS

In this paper,we study the existence of infinitely many homoclinic solutions for a class of first order Hamiltonian systems ż=J H_(z)(t,z),where the Hamiltonian function H possesses the form H(t,z)=1/2L(t)z⋅z+G(t,z),and G(t,z)is only locally defined near the origin with respect to z.Under some mild conditions on L and G,we show that the existence of a sequence of homoclinic solutions is actually a local phenomenon in some sense,which is essentially forced by the subquadraticity of G near the origin with respect to z.

High-order Hamiltonian obtained by Foldy-Wouthuysen transformation up to the order of mα^(8)

Complete relativistic corrections of an effective Hamiltonian for a single-particle system in an external electromagnetic field and their unitary equivalent form up to the order of mα^(8) are obtained.The derivation is based on two approaches applying Foldy-Wouthuysen(FW)transformation to the Dirac Hamiltonian for a particle in an external electromagnetic field.The results are consistent with the previous work at the mα^(6) and mα^(8) order correction[Phys.Rev.A 71012503(2005);Phys.Rev.A 100012513(2019)].We also further consider the effect of anomalous magnetic moments,namely,the Dirac-Pauli equation,and obtain FW-Hamiltonians at the same order.The results obtained can be used for the subsequent calculation of relativistic and radiation effects in simple atomic and molecular systems.

Crossing Limit Cycles of Planar Piecewise Hamiltonian Systems with Linear Centers Separated by Two Parallel Straight Lines

In this paper, we have studied several classes of planar piecewise Hamiltonian systems with three zones separated by two parallel straight lines. Firstly, we give the maximal number of limit cycles in these classes of systems with a center in two zones and without equilibrium points in the other zone (or with a center in one zone and without equilibrium points in the other zones). In addition, we also give examples to illustrate that it can reach the maximal number.

A Nonexistence Result for Choquard-Type Hamiltonian System

In this article, we establish a nonexistence result of nontrivial non-negative solutions for the following Choquard-type Hamiltonian system by the Pohožaev identity , when , , , , , and , where and denotes the convolution in .

Hamiltonian[k,k+1]-因子(英文)

本文考虑n/2-临界图中Hamiltonian[k,k+1]-因子的存在性。Hamiltonian[k,k+1]-因子是指包含Hamiltonian圈的[k,k+1]-因子;给定阶数为n的简单图G,若δ(G)≥n/2而δ(G\e)<n/2(对任意的e∈E(G)),则称G为n/2-临界图。设k为大于等于2的整数,G为n/2-临界图(其中n≥4k-6且n≥7),我们证明了对于G的任何Hamiltonian圈C,G中必存在包含C的[k,k+1]-因子。该结果改进了现有的一些有关Hamiltonian[k,k+1]-因子存在性的结果。

Comparison among Classical,Probabilistic and Quantum Algorithms for Hamiltonian Cycle Problem

The Hamiltonian cycle problem(HCP),which is an NP-complete problem,consists of having a graph G with n nodes and m edges and finding the path that connects each node exactly once.In this paper we compare some algorithms to solve a Hamiltonian cycle problem,using different models of computations and especially the probabilistic and quantum ones.Starting from the classical probabilistic approach of random walks,we take a step to the quantum direction by involving an ad hoc designed Quantum Turing Machine(QTM),which can be a useful conceptual project tool for quantum algorithms.Introducing several constraints to the graphs,our analysis leads to not-exponential speedup improvements to the best-known algorithms.In particular,the results are based on bounded degree graphs(graphs with nodes having a maximum number of edges)and graphs with the right limited number of nodes and edges to allow them to outperform the other algorithms.

两类树图的Hamiltonian色数

一个n阶连通图G的Hamiltonian染色是从G的顶点集V(G)到正整数集N(称为颜色集)的一个映射c,使得对于G的任意2个不同的顶点u和v满足|c(u)-c(v)|+D(u,v)≥n-1,其中D(u,v)表示G中u到v的最长路径的长度。对一个Hamiltonian染色c,将max{c(u):u∈V(G)}称为c的值,记作hc(c)。将min{hc(c):c是G的任意Hamiltonian染色}称为G的Hamiltonian色数,记作hc(G)。本次研究得到了满足max{D(u,v)|u,v∈V(G),u≠v}≤n/2的d-重似星树和广义双星这两类树图的Hamiltonian色数的确切值。

曲面上构造三次3-连通非Hamiltonian地图的一种方法(英文)

Tutte在1946年构造性证明了并非每个简单的3-凸胞腔都是Hamiltonian的后,人们又陆续提出了多种构造三次3-连通非Hamiltonian平面图的方法,但无一能用于在一般曲面上寻找三次3-连通非Hamiltonian地图.本文提出了一种新的构造方法,可在任一个曲面上构造出三次3-连通非Hamiltonian地图.

基于Hamiltonian马氏链蒙特卡罗方法的突变运动跟踪

在计算机视觉领域,由镜头切换、目标动力学突变、低帧率视频等引起的突变运动存在极大的不确定性,使得突变运动跟踪成为该领域的挑战性课题.以贝叶斯滤波框架为基础,提出一种基于有序超松弛Hamiltonian马氏链蒙特卡罗方法的突变运动跟踪算法.该算法将Hamiltonian动力学融入MCMC(Markov chain Monte Carlo)算法,目标状态被扩张为原始目标状态变量与一个动量项的组合.在提议阶段,为抑制由Gibbs采样带来的随机游动行为,提出采用有序超松弛迭代方法来抽取目标动量项.同时,提出自适应步长的Hamiltonian动力学实现方法,在跟踪过程中自适应地调整步长,以减少模拟误差.提出的跟踪算法可以避免传统的基于随机游动的MCMC跟踪算法所存在的局部最优问题,提高了跟踪的准确性而不需要额外的计算时间.实验结果表明,该算法在处理多种类型的突变运动时表现出出色的处理能力.

基于Hamiltonian理论的受控电力系统暂态稳定分析方法

从电力系统暂态能量函数出发,应用哈密顿系统理论首次提出新的李亚普诺夫函数。用该函数分析了具有切机切负荷稳定控制的简单电力系统的暂态稳定性。对单机无穷大系统的测试仿真结果表明:按该稳定性条件的切机控制能有效改善故障后系统的功角稳定性。最后指出了该研究的应用前景。