Workshop Spin-Orbit Coupling in Metal Oxides April 27, 2014 – May 02, 2014 Location: Columbus, Ohio Photo Credits: IFW-Dresden - Institute for Theoretical Solid State Physics, dan418 (stock.xchng), Hamish Johnston, Ceramics.org Organizers: Nandini Trivedi, The Ohio State University Mohit Randeria, The Ohio State University Patrick Woodward, The Ohio State University Transition metal oxides with partially filled 3d and 4d shells have dominated materials research in the past decades, leading to such spectacular phenomena as high Tc superconductivity and colossal magnetoresistance. In contrast, properties of materials like the oxides of rhenium, osmium and iridium, are only beginning to be explored. The presence of a large spin‐orbit coupling on the 5d elements, together with correlations, leads to the possibility of novel phases like topological Mott insulators and Weyl metals. The large variety of crystal structures (pyrochlore, hyper‐Kagome, etc.) in many cases leads to unusual anisotropic magnetic couplings and geometric frustration. Double perovskites with a 5d element are predicted, and in some cases known, to exhibit properties ranging from Mott insulators and spin‐liquids to insulating and half‐metallic ferrimagnets with very high Tc’s. Experimentally we know very little at this time about the effects of doping 5d Mott insulating phases. The aim of the workshop will be to bring researchers with diverse expertise in transition metal oxide experiments and theoretical modeling to focus on the latest developments in oxides with an interplay of strong correlations and spin‐orbit coupling. Topics to be covered during the workshop: •Magnetism: Spin and orbital ordering; Frustrated systems, Spin and orbital liquids, •Multi‐orbital Mott insulators: role of spin‐orbit coupling; doping effects •Topological properties: topological Mott insulators, Weyl metals, magnetoelectrics Tentative list of Invited Speakers: A. Bhattacharya (ANL) L. Balents (UCSB) I. Bozovic (BNL) L. Cooper (UIUC) G. Cao (Kentucky) J. Chakalian (Arkansas) C. Felser (Mainz) I. Fisher (Stanford) M. Franz (UBC) A. Georges (ENS) B. Keimer (MPI) H.‐Y. Kee (Toronto) Y‐B. Kim (Toronto) A. Khomskii (Groningen) G. Khaliullin (MPI) A. Millis (Columbia) N. Perkins (Madison) W. Pickett (UC Davis) G. Sawatzky (UBC) D. D. Sarma (IISc) A. Savrasov (Davis) R. Sheshadry (UCSB) N. Spaldin (ETH) T. Senthil (MIT) H. Takagi (Tokyo) A. Vishwanath (UC Berkeley)
不一定! 举例说明: Mapping the Core of the Arabidopsis Circadian Clock Defines the Network Structure of the Oscillator http://www.sciencemag.org/content/336/6077/75.short In many organisms, the circadian clock is composed of functionally coupled morning and evening oscillators. In Arabidopsis, oscillator coupling relies on a core loop in which the evening oscillator component TIMING OF CAB EXPRESSION 1 (TOC1) was proposed to activate a subset of morning-expressed oscillator genes(这是主流观点) . Here, we show that TOC1 does not function as an activator but rather as a general repressor of oscillator gene expression(实验结果把它推翻了). Repression occurs through TOC1 rhythmic association to the promoters of the oscillator genes(进一步阐明抑制机理). Hormone-dependent induction of TOC1 and analysis of RNA interference plants show that TOC1 prevents the activation of morning-expressed genes at night. Our study overturns the prevailing model of the Arabidopsis circadian clock, showing that the morning and evening oscillator loops are connected through the repressing activity of TOC1. 要不人家怎么能发Science呢?当实验结果和流行的理论矛盾的时候,才是真的考验功底的时候,进行研究的人也许会首先怀疑是自己错了，并为此而郁闷.但真正的行家,却会感到无比兴奋.正所谓山穷水复疑无路,柳暗花明又一村!科学研究什么最大?事实最大!这应该是做科研的一个最基本的信仰.
ISTART = 1 ICHARG=11 ISMEAR = 0 SIGMA = 0.1 ENCUT = 500 LCHARG = .TRUE NSW = 0 IBRION = 2 ISIF = 2 NEDOS = 3001 EMIN = -15.0 EMAX = 15.0 LORBIT = 11 #spin-orbit coupling #LSORBIT = .TRUE. #LORBMOM = .TRUE. #ISYM = 0 #ISPIN = 2 # Hybrid functional #LHFCALC = .TRUE. #HFSCREEN = 0.2 #ALGO =All #TIME = 0.4 #RPECFOCK = L ***************************************************************************************************** 增加一些解释，来自vasp官网 http://cms.mpi.univie.ac.at/vasp/vasp/Typical_hybrid_functional_Hartree_Fock_calculations.html Typical hybrid functional and Hartree-Fock calculations It is strongly recommended to perform standard DFT calculations first, and to start Hartree-Fock type calculations from a preconverged WAVECAR file. A typical INCAR file for a Hartree-Fock or hybrid HF/DFT calculation for an insulator or semiconductor has the following input lines: ISTART = 1 LHFCALC = .TRUE. ;HFSCREEN = 0.2 NBANDS = number of occupied bands ALGO = All ; TIME = 0.4 PRECFOCK = Fast ! used PRECFOCK = Normal for high quality calculations NKRED = 2 ! omit flag for high quality calculations For metals and small gap semiconductors it is recommended to use. ISTART = 1 LHFCALC = .TRUE. ; HFSCREEN = 0.2 ALGO = Damped ; TIME = 0.4 PRECFOCK = Fast ! used PRECFOCK = Normal for high quality calculations NKRED = 2 ! omit flag for high quality calculations These input files select the HSE06 functional, which tends to yield very similar thermochemistry as the PBE0 functional, but converges more rapidly with respect to the number of k-points . We thus recommend to apply and use this functional instead of the more demanding PBE0 functional. The NKRED flag is applicable, if and only if the number of k-points is dividable by NKRED (see Sec. 6.71.9 ). PRECFOCK= fast selects a smaller FFT grid for the fast-Fourier-transforms (see Sec. 6.71.5 ). For high accuracy NKRED and in particular PRECFOCK= fast should be ommited, but we recommend to do this only after preconverging the orbitals and atomic positions with the flags specified above. Mind, that the parameter TIME defaults to 0.4, and for the present algorithm this hardly ever needs to be changed. If divergence is observed, simply decrease TIME until the damped or conjugate gradient algorithm become stable (see Sec. 6.47 and 6.51 ). Standard Hartree-Fock type calculations require one to set the flag AEXX = 1.0 to switch on full non-local exchange (local exchange and correlation are automatically switched off): ISTART = 1 LHFCALC = .TRUE. ; AEXX = 1.0 ; NBANDS = number of occupied bands ALGO = All ; TIME = 0.4 PRECFOCK = Fast ! used PRECFOCK = Normal for high quality calculations NKRED = 2 ! omit flag for high quality calculations Concerning NKRED and PRECFOCK the same considerations as above apply. Matter of fact, it is also possible to try to converge using the ``metallic'' setup given above.
Coupling of modeFRONTIER v4 with Aspen Plus 2006 in a WIN32 OS environment Introduction Aspen Plus 2006 is a process simulation software commonly used for process engineering and chemical engineering tasks. In order to solve optimization problems such as sensitivity analysis’ in Aspen Plus 2006, a coupling of modeFRONTIER v4 optimization software with Aspen Plus 2006 on a WIN32 operating system will be carried out and documented in this paper. A simple process is chosen to explain the necessary steps of work. Description of a simple Aspen Plus 2006 simulation task Two input streams of H2O (H2O1 and H2O2) with different temperatures are fed into a static mixer (MIXER) and result in one output stream (H2OMIX) as shown in Figure 1. Figure 1: Aspen Plus 2006 User Interface Process Flowsheet window The stream input specifications are shown in Table 1. Table 1: Input stream specifications This simple example is run and will converge without errors (IDEAL property method). Optimization goal and modeFRONTIER v4 workflowsheet Aim of the sensitivity analysis, carried out by modeFRONTIER v4, is the maximization of the output stream mass flow while keeping the output stream temperature at as close to 62 °C (335 K) as possible. The modeFRONTIER v4 workflowsheet of this simple multi objective optimization problem is shown in Figure 2. Table 2 will explain the workflow nodes used in Figure 2. Figure 2: modeFRONTIER v4 workflowsheet Table 2: Description of workflow nodes Process flow in modeFRONTIER v4 4 input variables (as shown in Table 2) are set for this optimization problem. Their range of values is shown in Table 3. Table 3: Range of input variable values The input file window in modeFRONTIER v4 will look like Figure 3. Note that the input format is set to #0 so it will fit the format of the simu1.inp input file. Figure 3: Input Variable Properties window in modeFRONTIER v4 The simu1_inp node is an exported file of the Aspen Plus 2006 simulation explained in chapter 2 with the extension “.inp”. The complete log is shown below. This file is modified by modeFRONTIER v4 for each single optimization computation. Therefore it has been edited so modeFRONTIER v4 is able to locate the needed input information within the simu1.inp (see below). The simu1_out node is a Aspen Plus 2006 report file retrieved when running the simulation with the Aspen Plus 2006 Simulation Engine instead within the Aspen Plus 2006 User Interface environment. To start the Aspen Plus 2006 Simulation Engine from the Windows DOS-Console the following path has to be entered but may differ from machine to machine: Then the folder must be switched to the folder, where the simu1.inp is located. In this case it is stored in Now the simulation can be run with the following command: This command will start a simulation with the input information of the simu1.inp file. The optional indentifier /getridof will purge all unnecessary output files but also create a single simu1.out output file. The log of the operation is shown below. The modeFRONTIER v4 file output node simu1_out with the simu1.out file as input will look like below but is not shown completely because of its size. Note that the output units are different from the input units (for example °C input and K output). However this will not effect the correct computation of the optimization. The simu1.out will inherit the unit settings of the initial run of the simulation and in this way the units may be applied as requested. Note, that the output variables chosen for modeFRONTIER v4 are marked relative (red = variable, green = reference string) since the output file might change slightly and an absolute positioning could cause errors. The selected reference string should be unique throughout the file. The two output variables temp_out and flow_out are each connected to specific optimization goal nodes. The absolute value of the difference of 335 minus the outlet temperature in Kelvin shall be minimized. In other words the temperature should be as close to 62 °C (335 K) as possible. This is implemented in modeFRONTIER v4 as shown in Figure 4. Figure 4: Design Objective Properties window in modeFRONTIER v4 The second optimization objective is a simple maximization of output mass flow. Logic flow and DOS Batch script node in modeFRONTIER v4 The optimization wizard of modeFRONTIER v4 recommends a Multi Objective Generic Algorithm (MOGA II) with at least 8 generations (time for one simulation = 0,33 min; time for overall simulation = 0,2 h). Figure 5: Scheduler window in modeFRONTIER v4 The Design of Experiments (DOE) should be set to v4. Figure 6: Design of Experiments window in modeFRONTIER v4 The DOSBatch4 script node should be configured as shown in Figure 7. To enter the correct execution path the script window (red circle) has to be opened. The path is stated in “ ” so it is interpreted as a string (actual path may very from machine to machine). This allows advanced characters like spaces which otherwise may be interpreted incorrect. Figure 7: DOS-Batch Properties window in modeFRONTIER v4 Figure 8: DOS-Batch Script window in modeFRONTIER v4 However the identifiers at the end have to be stated outside the “ ”. With simu1 the simu1.inp input file will be used for the simulation and /getridof will purge all unnecessary report files and will create just one simu1.out output file. In this way also a lot of disc space will be saved when multiple simulations will be computed by modeFRONTIER v4. The Logic End node is implemented to terminate the optimization correctly. Run and analysis of the optimization The modeFRONTIER v4 project is saved under the file name simu1.prj in the directory The simulation is carried out, no error designs are created and a total of 31 design cases have been computed. The resulting Designs Table is shown in Figure 9. Figure 9: Designs Table of the simu1.prj Figure 10: Parallel Coordinates chart in modeFRONTIER v4 The optimal designs are marked with a green hook in column 3. The Parallel Coordinates chart (Figure 10) identifies two groups of designs: On group with maximum output of mass flow (design 3, 7, 10, 16, 18 27) and another group of minimal temperature difference to 335 K (design 1, 11, 22, 23 28). However the variety of answers is yet not satisfying so the optimization is run again, this time with a DOE of 10 designs and a MOGA II of 10 generations. The optimization completes with a total of 100 designs. A derived table of all important designs is shown in Figure 11. Duplicates have not been discarded. Figure 11: Optimal designs of second optimization run. In a 4D bubble chart the designs can be evaluated by the user as shown in Figure 12. Figure 12: 4D bubble chart of a derived designs table The user has to decide whether a trade-off solution is reasonable or if an extreme solution is desirable. Summary A coupling of Aspen Plus 2006 and modeFRONTIER v4 on a WIN32 operating system has been shown in this document. A simple simulation problem has been computed and was later evaluated in a sensitivity analysis.
Critical optical coupling between a GaAs disk and a nanowaveguide suspended on the chip C. Baker 1 , C. Belacel 2 , A. Andronico 1 , P. Senellart 2 , A. Lemaitre 2 , E. Galopin 2 , S. Ducci 1 , G. Leo 1 , and I. Favero 1 1 Laboratoire Matériaux et Phénomènes Quantiques, Université Paris Diderot, Sorbonne Paris Cité, CNRS-UMR 7162, 10 rue Alice Domon et Léonie Duquet, 75013 Paris, France 2 Laboratoire de Photonique et Nanostructures, CNRS, Route de Nozay, 91460 Marcoussis, France http://apl.aip.org/resource/1/applab/v99/i15/p151117_s1 (Received 2 August 2011; accepted 21 September 2011; published online 14 October 2011) Alert Me When Cited Alert Me When Corrected Download Citation Add to MyScitation Permissions / Reprints Blog This Article Print-Friendly Research Toolkit Email Abstract Connotea CiteULike del.icio.us BibSonomy Tweet this Article Add to Facebook We report on an integrated GaAs disk/waveguide system. A millimeter-long waveguide is suspended and tapered on the chip over a length of 25 μ m to evanescently couple to high Q optical whispering gallery modes of a GaAs disk. The critical coupling regime is obtained both by varying the disk/guide gap distance and the width of the suspended nanoscale taper. Experimental results are in good agreement with predictions from coupled mode theory.
亮哥近日整理了他的计算MSF的程序（fortran），科学网的各位有需要的话可以email我 ryang8@asu.edu 为第一时间给您回复，请尽量有英文。。谢谢理解了。。 其中文献1可以是一个非常好的工具，上面研究了几乎所有的非线性系统，研究对于不同类型的coupling，不同大小的coupling strength，其对主稳定函数以及同步性能的影响。 Master-stability functions MSFs are fundamental to the study of synchronization in complex dynamical systems. For example, for a coupled oscillator network, a necessary condition for synchronization to occur is that the MSF at the corresponding normalized coupling parameters be negative. To understand the typical behaviors of the MSF for various chaotic oscillators is key to predicting the collective dynamics of a network of these oscillators. We address this issue by examining, systematically, MSFs for known chaotic oscillators. Our computations and analysis indicate that it is generic for MSFs being negative in a finite interval of a normalized coupling parameter. A general scheme is proposed to classify the typical behaviors of MSFs into four categories. These results are verified by direct simulations of synchronous dynamics on networks of actual coupled oscillators. References: L. Huang, Q.-F. Chen, Y.-C. Lai , and L. M . Pecora, ``Generic behavior of master -stability functions in coupled nonlinear dyna m ical syste m s,'' Physical Review E 80 , 036204 (2009). R. Yang, L. Huang, and Y.-C. Lai , ``Transient disorder in dyna m ically growing networks,'' Physical Review E 79 , 046101 (2009).
11 August 2010 Chinese chemists have successfully coupled aromatic molecules without the use of a transition metal catalyst - something that people have been trying to do for years with little success. Such cross-coupling reactions are crucial to organic synthesis and typically require expensive metals such as palladium. Efforts to find cheaper and more widely available alternatives have proved challenging. Now, Wei Liu, from Wuhan University, and colleagues appear to have succeeded by using an organic catalyst, DMEDA ( N,N '-dimethylethane-1,2-diamine) in the presence of the base potassium tert -butoxide. The team coupled unactivated benzene with a range of aryl iodides in the presence of the organic catalyst and the base. We have checked for contamination and excluded the involvement of trace amounts of transition metals - Aiwen Lei, Wuhan University The researchers suggest that the reaction proceeds via the formation of a radical, with the potassium salt initiating radical formation in the presence of DMEDA. 'In radical trap experiments the coupling was inhibited by a classical radical scavenger which suggested that radical species are involved,' says team member Aiwen Lei. Could trace amounts of transition metal have contaminated the experiment? 'Obviously this is one of the most important factors,' says Lei. 'We have checked the contamination of trace amounts of transition metals by ICP and excluded the involvement of small amounts of transition metals in this transformation.' In addition, the potassium tert -butoxide used in the work was purified by sublimation to remove any contaminants. Lei believes that the work could herald a new direction in organic synthesis. 'This is the first report of organocatalysis in carbon-carbon coupling or direct arylation between aryl halides and arenes, which could be considered as a conceptually different approach towards biaryl syntheses.' Commenting on the work, Carsten Bolm, an organic synthesis expert fromAachenUniversityinGermany, says, 'To be able to prepare cross-coupling products without the use of transition metals is an important scientific advance. Although at thepresent stage the substrate scope is by far too limited to make the process synthetically attractive, the findings illustrate that new reaction paths in direct C-H arylations are still to be discovered, and as such this work will be highly stimulating to the community.' Simon Hadlington Interesting? Spread the word using the 'tools' menu on the left. References W Liu et al , J. Am. Chem. Soc ., 2010, DOI: 10.1021/ja103050x http://www.rsc.org/chemistryworld/News/2010/August/11081002.asp
标签: coupling
