Acoustic Phonon Impact on the Inter Coulombic Decay Process in Charged Quantum Dot Pairs

Recently, highly accurate multi configuration time dependent Hartree electron dynamics calculations demonstrated the efficient long range energy transfer inter Coulombic decay ICD process to happen in charged semiconductor quantum dot QD pairs. ICD is initiated by intraband photoexcitation of one of the QDs and leads to electron emission from the other within a duration of about 150 ps. On the same time scale electronically excited states are reported to relax due to the coupling of electrons to acoustic phonons. Likewise, phonons promote ionisation. Here, the QDs acoustic breathing mode is implemented in a frozen phonon approach. A detailed comparison of the phonon effects on electron relaxation and emission as well as on the full ICD process is presented, which supports the previous empirical finding of ICD being the dominant decay channel in paired QDs. In addition the relative importance of phonon phonon, phonon electron and electron electron interaction is analyse

The DDG^G-classifier in the functional setting

The Maximum Depth was the first attempt to use data depths instead of multivariate raw data to construct a classification rule. Recently, the DD-classifier has solved several serious limitations of the Maximum Depth classifier but some issues still remain. This paper is devoted to extending the DD-classifier in the following ways: first, to surpass the limitation of the DD-classifier when more than two groups are involved. Second to apply regular classification methods (like $k$NN, linear or quadratic classifiers, recursive partitioning,...) to DD-plots to obtain useful insights through the diagnostics of these methods. And third, to integrate different sources of information (data depths or multivariate functional data) in a unified way in the classification procedure. Besides, as the DD-classifier trick is especially useful in the functional framework, an enhanced revision of several functional data depths is done in the paper. A simulation study and applications to some classical real datasets are also provided showing the power of the new proposal.Comment: 29 pages, 6 figures, 6 tables, Supplemental R Code and Dat

The geometry of recursion operators

We study the fields of endomorphisms intertwining pairs of symplectic structures. Using these endomorphisms we prove an analogue of Moser's theorem for simultaneous isotopies of two families of symplectic forms. We also consider the geometric structures defined by pairs and triples of symplectic forms for which the squares of the intertwining endomorphisms are plus or minus the identity. For pairs of forms we recover the notions of symplectic pairs and of holomorphic symplectic structures. For triples we recover the notion of a hypersymplectic structure, and we also find three new structures that have not been considered before. One of these is the symplectic formulation of hyper-Kaehler geometry, which turns out to be a strict generalization of the usual definition in terms of differential or Kaehler geometry.Comment: cosmetic changes only; to appear in Comm. Math. Phy

Interdependence of ICD Rates in Paired Quantum Dots on Geometry

Using state of the art antisymmetrized multiconfiguration time dependent Hartree MCTDH electron dynamics calculations we study the interdependence of the intermolecular Coulombic decay ICD process on the geometric parameters of a doubly charged paired quantum dot PQD model system in the framework of the effective mass approximation EMA . We find that ICD displays a maximum rate for a certain geometry of the electron emitting quantum dot, which is simultaneously dependent on both the distance between the quantum dots as well as the photon absorbing quantum dot s geometry. The rate maximum is shown to be caused by the competing effects of polarization of electron density and Coulomb repulsion. The ICD rate maximized PQD geometry in GaAs QDs yields a decay time of 102.39 ps. It is given by two vertically aligned cylindrical QDs with radii of 14.42 nm separated by 86.62 nm. The photon absorbing QD then has a height of 46.59 nm and the electron emitting QD a height of 16.33 n

Strong Field Control of the Interatomic Coulombic Decay Process in Quantum Dots

In recent years the laser induced interatomic Coulombic decay ICD process in paired quantum dots has been predicted [J. Chem. Phys. 138 2013 214104]. In this work we target the enhancement of ICD by scanning over a range of strong field laser intensities. The GaAs quantum dots are modeled by a one dimensional double well potential in which simulations are done with the space resolved multi configuration time dependent Hartree method including antisymmetrization to account for the fermions. As a novelty a complementary state resolved ansatz is developed to consolidate the interpretation of transient state populations, widths obtained for the ICD and the competing direct ionization channel, and Fano peak profiles in the photoelectron spectra. The major results are that multi photon processes are unimportant even for the strongest fields. Further, below pi to pi pulses display the highest ICD efficiency while the direct ionization becomes less dominan

Intuitive Understanding of sigma Delocalization in Loose and sigma Localization in Tight Helical Conformations of a Saturated Chain Oligosilanes

Conformational effects on the amp; 963; electron delocalization in oligosilanes are addressed by Hartree Fock and time dependent density functional theory calculations B3LYP, 6 311G at MP2 optimized geometries of permethylated uniformly helical linear oligosilanes all amp; 969; SinR2n 2 up to n 16 and for backbone dihedral angles amp; 969; 55 180 . The extent of amp; 963; delocalization is judged by the partition ratio of the highest occupied molecular orbital and is reflected in the dependence of its shape and energy and of UV absorption spectra on n. The results agree with known spectra of all transoid loose helix conformers all [ 165] SinMe2n 2 and reveal a transition at amp; 969; amp; 8776;90 from the amp; 963; delocalized limit at amp; 969; 180 toward and close to the physically non realizable amp; 963; localized tight helix limit amp; 969; 0 with entirely different properties. The distinction is also obtained in the Hückel Ladder H and C models of amp; 963; delocalization. An easy intuitive way to understand the origin of the two contrasting limits is to first view the linear chain as two subchains with alternating primary and vicinal interactions amp; 963; hyperconjugation , one consisting of the odd and the other of the even amp; 963; SiSi bonds, and then allow the two subchains to interact by geminal interactions amp; 963; conjugatio

Three electron dynamics of the interparticle Coulombic decay with two dimensional continuum confinement

In a pair of self assembled or gated laterally arranged quantum dots, an electronically excited state can undergo interparticle Coulombic decay. Then, an electron from a neighbor quantum dot is emitted into the electronic continuum along the two available dimensions. This study proves that the process is not only operative among two but also among three quantum dots, where a second electron emitting dot causes a rate increase by a factor of two according to the predictions from the analytical Wigner Weisskopf rate equation. The predictions hold over the complete range of conformation angles among the quantum dots and over a large range of distances. Electron dynamics was calculated by multiconfiguration time dependent Hartree and is, irrespective of the large number of discrete variable representation grid points, feasible after having developed an OpenACC graphic card compilation of the progra

Six Sigma: A novel approach to pharmaceutical industry

The statistical concept, six sigma is used to define problems systematically, provides tools to measure and influential factors and identifies the improvements that can be implemented easily. It is quality management tool which can be considered as a vision, a philosophy, a symbol, a metric, a goal, a methodology. It simply means a measure of quality that struggle for near perfection. It is a highly disciplined process that focuses on developing and deliveringNear perfect product and services It is based on three element Process improvement, Process. Design/re-design and Process management. When we use this technique for a process then process variation reduced to 3.4 DPMO (Defects per million Opportunities).Six sigma is divided in two sub methods DMAIC (Define, Measure, Analyze, Improve and Control) is improvement system for existing processes that doesnt meet specification. DMADV (Define, Measure, Analyze, Design, Verify) is used to develop new processes at six sigma level