HOCl分子高激发振动态的动力学势研究

通过研究HOC1分子高激发振动态的动力学势,明确了该体系的动力学特点.研究表明,在O-C1伸缩模式和H-O-C1弯曲模式间存在2:1 Fermi共振的动力学模型下,H-O伸缩振动模式对于上述两种振动模式的动力学势有显著影响,且这种影响随Polyad数呈现有规律的变化.作为定量研究,还研究了Polyad数为24时该分子体系的动力学势与各能级的相空间轨迹.分析表明,相空间轨迹与动力学势中的动力学不动点有很好的对应关系.此外,将该Polyad数下的动力学势中的能级按照相空间轨迹的作用量积分进行分类,明确了这些能级所处的量子环境.

基于信息及其作用机制的教育原理创新与理论范式变革——势科学暨信息动力学视角

教育过程即人才成长过程,是信息相互作用的动力学过程。从势科学暨信息动力学的视角来看,教育学研究的核心要素信息=差别×联系,具有倒数的本质。差别和联系这两个教育要素构成了教育的绩效函数。教育学进行科学化研究的根本路径,就是在教育过程的不同层次上,将差别最大的教育要素紧密联系起来。

创新型人才成长机制与教育路径研究——基于势科学与信息动力学理论

从势科学与信息动力学理论来看,创新型人才素质的形成遵循"差别促进联系,联系扩大差别"的势增原理,实现创新思维的跃进、创新知识的有序、创新能力的发展以及创新素质的成群。培养创新型人才必须遵循创新型人才成长的特性,并通过思维导势、教育蓄势、课堂造势、对称成势等途径,开展信息量最大、作用量最小的教育活动,营造强大的信息势,最终实现创新型人才的培养。

扁球薄壳在大挠度下的非线性动力稳定性

根据薄壳非线性动力学理论,由扁球薄壳大挠度基本方程,在周边固定夹紧的条件下,用修正迭代法求出二次近似解析解,把大挠度解作为扁球薄壳的初挠度处理,推导出扁球薄壳在大挠度下的非线性动力学基本方程。然后给出满足夹紧固定边界条件下的位移模式,求出张力。由动力学势的一阶变分为零得到平衡曲面方程。继之用突变理论给出相应的分岔点集的方程组,同时讨论了扁球薄壳整体的稳定性问题。该文也给出了相应平衡曲面的分岔点集的示意图。

超音速等离子体炬的磁流体动力学数值研究

针对设计的喉径2mm、工作电流为100A的拉瓦尔喷嘴,在二维轴对称模型的基础上,对超音速等离子体炬中的流动及其外部射流进行了数值模拟。通过在阳极喷嘴内部采用基于磁矢量势的磁流体动力学模型,避免了对磁感应强度的复杂积分计算,得到了喷嘴内部多场耦合的结果及外部射流的流动状态,分析了喷嘴内部电磁场对等离子体的加速作用及射流发展过程。结果显示,等离子体经历了亚音速→跨音速→超音速的发展过程,最终获得2.3 Ma的超音速射流。研究结果为超音速等离子体炬的工业应用提供了理论基础。

α-Al_2O_3(0001)表面吸附ZnO的DFT研究

建立了α-Al2 O3( 0 0 0 1 ) 2× 1表面薄片吸附模型 ,采用基于 DFT动力学赝势方法 ,对 Zn O分子的吸附生长进行了计算 .详细地研究了 Zn O分子在表面吸附的成键方式以及表面化学键特性 .在较稳定的吸附位上 ,Zn O化学键 [( 0 .1 85± 0 .0 1 ) nm]与最近邻的表面 Al— O键有 3 0°的偏转角度 ,Zn在表面较稳定的化学吸附位置偏离表面 O六角对称约 3 0°.通过吸附能量、原子布居数和态密度的分析 ,Zn O的 O2 -与表面上的Al3+形成的化学键表现出强离子键特征 ;而 Zn2 +同基片表面 O2

Water quality changing trends of the Miyun Reservoir

In order to simulate changes in the water quality of the Miyun Reservoir dueto continuous descent of surface water level, a 3-D ecological hydrodynamic model was developedthrough coupling the water quality analysis simulation program (WASP) with the environmental fluiddynamics code (EFDC). The model was then calibrated and verified. Four scenarios (S1, S21, S22 andS23) were simulated using the model. Results show that the water quality of the Miyun Reservoirunder conditions of low surface water level is apparently affected by different amounts of inflowand different total phosphorus (TP) loadings. The chlorophyll-a concentration might exceed 10 μg/Lin many areas of the Miyun Reservoir (This limitative value is seen as a critical value ofeutrophication) when large loadings of TP enter due to the amount of inflow increasing. Results ofscenario S23 indicate that control of TP loadings can decrease chlorophyll-a concentrationeffectively, and the water quality of the Miyun Reservoir will improve or retain its status quo.

双阳极超音速等离子体炬数值模拟研究

针对某拉瓦尔喷嘴,在二维轴对称模型的基础上,采用基于磁矢量势的磁流体力学控制方程,对双阳极模式下超音速等离子体炬中的流动及其外部射流进行了数值模拟。在阳极喷嘴内部,运用虚拟阳极的方法,得到了双阳极模式下喷嘴内部多场耦合的结果及外部射流的流动状态。分析了弧根位置变化对等离子体流动特性的影响,为双阳极超音速等离子体炬的工业应用提供了理论基础。

Kinetics Study on O2 Adsorption and OHad Desorption at Pt（111）, Its Implication to Oxygen Reduction Reaction Kinetics

Kinetics of dissociative O2 adsorption, OHad desorption, and oxygen reduction reaction （ORR） at Pt（111） electrode in 0.1 mol/L HClO4 has been investigated. Reversible OHad adsorption/desorption occurs at potentials from 0.6 V to 1.0 V （vs. RHE） with the exchange current density of ca. 50 mA/cm^2 at 0.8 V, the fast kinetics of OHad desorption indicates that it should not be the rate determining step for ORR. In the kineticor kinetic-mass transport mix controlled potential region, ORR current at constant potential displays slight decrease with reaction time. ORR current in the positive-going potential scan is slightly larger than that in the subsequent negative-going scan with electrode rotation speed （〉800 r/min） and slow potential scan rate （〈100 mV/s）. The open circuit potential of Pt/0.1 mol/L HClO4 interface increases promptly from 0.9 V to 1.0 V after switch from O2 free- to O2-saturated solution. The increase of open circuit potential as well as ORR current decays under potential control due to the accumulation of OHad from dissociative adsorption of O2. It indicates that at Pt（111） the net rate for O2 decomposition to OHad is slightly faster than that for OHad removal, one cannot simply use the assumption of rate determining step to discuss ORR kinetics. Instead, the ORR kinetics is determined by both the kinetics for O2 decomposition to OHad as well as the thermo-equilibrium of OHad＋H^＋＋e→←H2O.

Targeted design of advanced electrocatalysts by machine learning

Exploring the production and application of clean energy has always been the core of sustainable development.As a clean and sustainable technology,electrocatalysis has been receiving widespread attention.It is crucial to achieve efficient,stable and cheap electrocatalysts.However,the traditional“trial and error”method is time-consuming,laborious and costly.In recent years,with the significant increase in computing power,computations have played an important role in electrocatalyst design.Nevertheless,it is still difficult to search for advanced electrocatalysts in the vast chemical space through traditional density functional theory(DFT)computations.Fortunately,the development of machine learning and interdisciplinary integration will inject new impetus into targeted design of electrocatalysts.Machine learning is able to predict electrochemical performances with an accuracy close to DFT.Here we provide an overview of the application of machine learning in electrocatalyst design,including the prediction of structure,thermodynamic properties and kinetic barriers.We also discuss the potential of explicit solvent model combined with machine learning molecular dynamics in this field.Finally,the favorable circumstances and challenges are outlined for the future development of machine learning in electrocatalysis.The studies on electrochemical processes by machine learning will further realize targeted design of high-efficiency electrocatalysts.

Monte Carlo Hamiltonian：Linear Potentials

We further study the validity of the Monte Carlo Hamiltonian method. The advantage of the method, in comparison with the standard Monte Carlo Lagrangian approach, is its capability to study the excited states. We consider two quantum mechanical models: a symmetric one ; and an asymmetric one , for and , for . The results for the spectrum, wave functions and thermodynamical observables are in agreement with the analytical or Runge–Kutta calculations.

Structures and Dynamics of a Two-Dimensional Confined Dusty Plasma System

The influence of the confining potential strength and temperature on the structures and dynamics of a two-dimensional (2D) dusty plasma system is investigated through molecular dynamic (MD) simulation. The circular symmetric confining potential leads to the nonuniform packing of particles, that is, an inner core with a hexagon lattice surrounded by a few outer circular shells. Under the appropriate confining potential and temperature, the particle trajectories on middle shells form a series of concentric and nested hexagons due to tangential movements of particles.Mean square displacement, self-diffusion constant, pair correlation function, and the nearest bond are used to characterize the structural and dynamical properties of the system. With the increase of the confining potential, the radial and tangential movements of particles have different behaviors. With the increase of temperature, the radial and tangential motions strengthen, particle trajectories gradually become disordered, and the system gradually changes from a crystal or liquid state to a gas state.

A Quantum Wavepacket Study of State-to-State Photodissociation Dynamics of HOBr/DOBr

Photodissociation of HOBr is an important step in the reaction network of the depletion of ozone in stratosphere.Here,we report the first three-dimensional potential energy surfaces for the lowest three singlet states for HOBr,based on high level multi reference configuration interaction calculations.Quantum dynamics calculations are performed with a real wavepacket method,yielding not only absorption spectra but also internal state and angular distributions of the photodissociation fragments.Our results agree quantitatively with the measured total absorption cross sections of HOBr in the ultraviolet region and reproduce well the observed vibrationally cold and rotationally hot OH/OD fragments via photodissociation of HOBr/DOBr at 266 nm.In addition,we predict that the recoil anisotropy parameters for OH/OD are close to the limiting value of a parallel transition,suggesting a rapid dissociation process at 266 nm following an in-plane transition from the ground state(1^1A')to the 21A'state.This is consistent with the experimental conclusion derived from the measured rotational alignment.However,spin and electronic angular momenta need to be taken into account in the future to achieve a more quantitative agreement with experiment.Our work is expected to motivate further experimental investigations for this benchmark system.

Quasi-Classical Trajectory Investigation of H+SO_(2)→OH+SO Reaction on Full-Dimensional Accurate Potential Energy Surface

The reaction H+SO_(2)→OH+SO is important in the combustion and atmospheric chemistry,as well as the interstellar medium.It also represents a typical complex-forming reaction with deep complexes,serving as an ideal candidate for testing various kinetics theories and providing interesting reaction dynamical phenomena.In this work,we reported a quasiclassical trajectory study of this reaction on our previously developed accurate full-dimensional potential energy surface.The experimental thermal rate coefficients over the temperature range 1400 K≤T≤2200 K were well reproduced.For the reactant SO_(2)being sampled at the ground ro-vibrational state,the calculated integral cross sections increased slightly along the collision energy ranging from 31.0 kcal/mol to 40.0 kcal/mol,and then became essentially flat at the collision energy within 40.0−55.0 kcal/mol.The product angular distributions are almost symmetric with nearly identical backward-forward double peak structure.The products OH and SO vibrational state distributions were also analyzed.

Extended Quark Potential Model From Random Phase Approximation

The quark potential model is extended to include the sea quark excitation using the random phase approximation. The effective quark interaction preserves the important QCD properties — chiral symmetry and confinement simultaneously. A primary qualitative analysis shows that the π meson as a well-known typical Goldstone boson and the other mesons made up of valence quark pair such as the ρ meson can also be described in this extended quark potential model.

Biased Motion in a Symmetric Periodic Potential by Breaking Temporal Sysmmetry

Unidirectional transport of a particle in a spatially periodic and symmetric potential under a periodic force with broken temporal symmetry is studied. With a collaboration of the potential field and the asymmetric ac force, a dc current can be observed. Resonant current steps are found for a finite period of the ac force. A phase diagram of these resonant steps is given. Stochastic-resonance-like directional transport induced by thermal noises is revealed.

Glass Formation of n-Butanol： Coarse-grained Molecular Dynamics Simulations Using Gay-Berne Potential Model

Using coarse-grained molecular dynamics simulations based on Gay-Berne potential model, we have simulated the cooling process of liquid n-butanol. A new set of GB parameters are obtained by fitting the results of density functional theory calculations. The simulations are carried out in the range of 290-50 K with temperature decrements of 10 K. The cooling characteristics are determined on the basis of the variations of the density, the potential energy and orientational order parameter with temperature, whose slopes all show discontinuity. Both the radial distribution function curves and the second-rank orientational correlation function curves exhibit splitting in the second peak. Using the discontinuous change of these thermodynamic and structure properties, we obtain the glass transition at an estimate of temperature Tg=1204.10 K, which is in good agreement with experimental results 1104-1 K.

A Model Study of Equation of State of QCD at Finite Chemical Potential and Zero Temperature

In this paper, we give a direct method for calculating the partition function, and hence the equation of state （EOS） of QCD at finite chemical potential and zero temperature. In the EOS derived in this paper the pressure density is the sum of two terms： the first term P（μ）｜μ=0 （the pressure density at μ = 0） is a μ-independent constant; the second term, which is totally determined by G[μ] （p） （the dressed quark propagator at finite μ）, contains all the nontrivial μ-dependence. By applying a general result in the rainbow-ladder approximation of the Dyson-Schwinger approach obtained in our previous study [Phys. Rev. C 71 （2005） 015205], G[μ]（p） is calculated from the meromorphic quark propagator proposed in [Phys. Rev. D 67 （2003） 054019]. From this the full analytic expression of the EOS of QCD at finite μ and zero T is obtained （apart from the constant term P（μ）｜μ=0, which can in principle be caJculated from the CJT effective action）. A comparison between our EOS and the cold, perturbative EOS of QCD of Fraga, Pisarski and Schaffner-Bielich is made. It is expected that our EOS can provide a possible new approach for the study of neutron stars.

Theoretical Simulations of Irradiation-Induced Sputtering at Tungsten Surface

The irradiation-induced sputtering and the structural damage at tungsten surface are investigated by using molecular dynamics simulations at the level of quantum mechanics. Our simulations indicate that the sputtered atoms appear when the energy of incident primary knock-on atom （PKA） is more than 200 eV and the incident angle of the PKA is larger than 65°. Meanwhile, the irradiation-induced vacancies are less when the incident angle of PKA is in the range of 45°-65°. So, the optimum incident angles of PKA are suggested to reduce the irradiation-induced damage of the W surface. Furthermore, we find that the interstitials contained in the systems accelerate the sputtering whereas the intrinsic vacancies suppress the sputtering when the PKA is near the defects.

Quantum Dynamics of Oxyhydrogen Complex-Forming Reactions for the HO2 and HO3 Systems

Complex-forming reactions widely exist in gas-phase chemical reactions. Various complexforming bimolecular reactions have been investigated and interesting phenomena have been discovered. The complex-forming reactions usually have small or no barrier in the entrance channel, which leads to obvious differences in kinetic and dynamic characteristics compared with direct reactions. Theoretically, quantum state-resolved reaction dynamics can provide the most detailed microscopic dynamic mechanisms and is now feasible for a direct reaction with only one potential barrier. However, it is of great challenge to construct accurate potential energy surfaces and perform accurate quantum dynamics calculations for a complex polyatomic reaction involving deep potential wells and multi-channels. This paper reviews the most recent progress in two prototypical oxyhydrogen complex-forming reaction systems, HO2 and HO3, which are significant in combustion, atmospheric, and interstellar chemistry. We will present a brief survey of both computational and experimental work and emphasize on some unsolved problems existing in these systems.