A SYNTHETIC ANALYSIS ON DESIGN OF OPTIMUM CONTROL FOR AN OPTIMIZED INTELLIGENT STRUCTURE

A hybrid optimization algorithm is developed to minimize the control energy and the structural weight under the constraints of the structural dynamic property requirements. A 72-bar space truss with two piezoelectric actuators is used to illustrate the complete process of this algorithm. It is shown that the control energy and the structural weight are clearly reduced using the proposed method.     

Linear-scaling quantum mechanical methods for excited states

The poor scaling of many existing quantum mechanical methods with respect to the system size hinders their applications to large systems. In this tutorial review, we focus on latest research on linear-scaling or O(N) quantum mechanical methods for excited states. Based on the locality of quantum mechanical systems, O(N) quantum mechanical methods for excited states are comprised of two categories, the time-domain and frequency-domain methods. The former solves the dynamics of the electronic systems in real time while the latter involves direct evaluation of electronic response in the frequency-domain. The localized density matrix (LDM) method is the first and most mature linear-scaling quantum mechanical method for excited states. It has been implemented in time- and frequency-domains. The O(N) time-domain methods also include the approach that solves the time-dependent Kohn-Sham (TDKS) equation using the non-orthogonal localized molecular orbitals (NOLMOs). Besides the frequency-domain LDM method, other O(N) frequency-domain methods have been proposed and implemented at the first-principles level. Except one-dimensional or quasi-one-dimensional systems, the O(N) frequency-domain methods are often not applicable to resonant responses because of the convergence problem. For linear response, the most efficient O(N) first-principles method is found to be the LDM method with Chebyshev expansion for time integration. For off-resonant response (including nonlinear properties) at a specific frequency, the frequency-domain methods with iterative solvers are quite efficient and thus practical. For nonlinear response, both on-resonance and off-resonance, the time-domain methods can be used, however, as the time-domain first-principles methods are quite expensive, time-domain O(N) semi-empirical methods are often the practical choice. Compared to the O(N) frequency-domain methods, the O(N) time-domain methods for excited states are much more mature and numerically stable, and have been applied widely to investigate the dynamics of complex molecular systems.     

Supramolecular Self-assembly of Amphiphilic Alkynyl-platinum(II) 2,6-Bis(N-alkylbenzimidazol-2'-yl) pyridine Complexes

Alkynylplatinum(II) bzimpy complexes of trimethylammonium-benzylethynyl ligand have been synthesized and characterized. Complexes with long alkyl chains have been found to exhibit interesting self-assembly properties in the acetonitrile solution. The amphiphilic nature of the complexes has led to the formation of nanorods, as revealed by electron microscopy experiments. Further increasing the polarity of the solvent media has given rise to the enhancement of low-energy emission.     

Multiscale quantum mechanics/electromagnetics simulation for electronic devices

The continuous downsizing of modern electronic devices implies the increasing importance of quantum phenomena. As the feature sizes of transistors inch towards 10 nanometer, simulations including quantum effects and atomistic details are inevitable. Here we report a novel hybrid quantum mechanics and electromagnetics (QM/EM) method to model individual electronic components at the nanoscale. QM and EM models are solved in different regions of the system in a self-consistent manner. As a demonstration, we study a carbon nanotube based electronic device embedded in a silicon block. Good agreement is obtained between simulation by QM/EM method and full QM treatment of the entire system.     

金属锰Corrole的脱金属研究

合成了中位带有不同取代基的锰corrole配合物1-Mn, 2-Mn, 3-Mn, 4-Mn,并研究了其酸解和还原脱金属特性。结果表明取代基的性质对脱金属产率有很大的影响。缺电子金属锰corrole的酸解脱金属产率比富电子金属锰corrole高,而还原脱金属产率的顺序则正好相反。     

Linear-scaling computation of excited states in time-domain

The applicability of quantum mechanical methods is severely limited by their poor scaling.To circumvent the problem,linearscaling methods for quantum mechanical calculations had been developed.The physical basis of linear-scaling methods is the locality in quantum mechanics where the properties or observables of a system are weakly influenced by factors spatially far apart.Besides the substantial efforts spent on devising linear-scaling methods for ground state,there is also a growing interest in the development of linear-scaling methods for excited states.This review gives an overview of linear-scaling approaches for excited states solved in real time-domain.     

甲胺基-甲脒基混合钙钛矿的第一性原理研究

有机铅卤钙钛矿APbX_3的稳定性是制约其应用的重要因素,对APbX_3钙钛矿中A和X采用不同种类离子混合的化学组分调控是改进其稳定性最有效的方式之一。其中,A位点采用不同比例的甲脒离子(FA)和甲胺离子(MA)是当前研究的热点方向。本文通过第一性原理计算,系统研究了FA_(1-x)MA_xPbI_3体系的结构和光电性质。研究发现FA与MA的混合增加体系的稳定性,其中FA_(0.5)MA_(0.5)PbI_3最稳定。通过分析不同混合比例的结构,揭示了晶格常数随x的增加线性减小;以及带隙随x减小而线性增加。此外,计算结果发现MA所占比例增加时吸收光谱蓝移。研究表明通过FA和MA离子的混合能有效调控钙钛矿的光电性质,从而获得更有效的钙钛矿太阳能电池。     

Molecular Design of Luminescent Metal-Based Materials

Polynuclear transition metal complexes have been shown to exhibit rich luminescence behavior. The recent reports on the potential applications of alkynyl metal complexes as nonlinear optical materials, molecular wires and rigid-rod materials, and the wide variety of possible bonding modes of the alkynyl moiety have aroused our interest in investigating their potential in the design and synthesis of di- and polynuclear metal complexes. In this presentation, the design and successful isolation of a series of soluble di- and polynuclear transition metal acetylides with rich luminescence behavior will be described11,21.     

Existence of time-dependent density-functional theory for open electronic systems: time-dependent holographic electron density theorem

We present the time-dependent holographic electron density theorem (TD-HEDT), which lays the foundation of time-dependent density-functional theory (TDDFT) for open electronic systems. For any finite electronic system, the TD-HEDT formally establishes a one-to-one correspondence between the electron density inside any finite subsystem and the time-dependent external potential. As a result, any electronic property of an open system in principle can be determined uniquely by the electron density function inside the open region. Implications of the TD-HEDT on the practicality of TDDFT are also discussed.