{"title":"Stability of gap soliton complexes in the nonlinear Schrödinger equation with periodic potential and repulsive nonlinearity","authors":"P. P. Kizin","doi":"10.20537/vm160412","DOIUrl":"https://doi.org/10.20537/vm160412","url":null,"abstract":"The work is devoted to numerical investigation of stability of stationary localized modes (\"gap solitons\") for the one-dimentional nonlinear Schr\"odinger equation (NLSE) with periodic potential and repulsive nonlinearity. Two classes of the modes are considered: a bound state of a pair of in-phase and out-of-phase fundamental gap solitons (FGSs) from the first bandgap separated by various number of empty potential wells. Using the standard framework of linear stability analysis, we computed the linear spectra for the gap solitons by means of the Fourier collocation method and the Evans function method. We found that the gap solitons of the first and second classes are exponentially unstable for odd and even numbers of separating periods of the potential, respectively. The real parts of unstable eigenvalues in corresponding spectra decay with the distance between FGSs exponentially. On the contrary, we observed that the modes of the first and second classes are either linearly stable or exhibit weak oscillatory instabilities if the number of empty potential wells separating FGSs is even and odd, respectively. In both cases, the oscillatory instabilities arise in some vicinity of upper bandgap edge. In order to check the linear stability results, we fulfilled numerical simulations for the time-dependent NLSE by means of a finite-difference scheme. As a result, all the considered exponentially unstable solutions have been deformed to long-lived pulsating formations whereas stable solutions conserved their shapes for a long time.","PeriodicalId":154515,"journal":{"name":"arXiv: Pattern Formation and Solitons","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134218851","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P. Grinevich, P. L. I. F. T. Physics, Russia., Lomonosov Moscow State University, M. Physics, Technology, D. Fisica, Universita di RomaLa Sapienza'', Italy., Istituto Nazionale Fisica Nucleare, Sezione di Roma, 2. Italy.Piazz.leAldoMoro, I-00185 Roma
{"title":"Numerical instability of the Akhmediev breather and a finite-gap model of it","authors":"P. Grinevich, P. L. I. F. T. Physics, Russia., Lomonosov Moscow State University, M. Physics, Technology, D. Fisica, Universita di RomaLa Sapienza'', Italy., Istituto Nazionale Fisica Nucleare, Sezione di Roma, 2. Italy.Piazz.leAldoMoro, I-00185 Roma","doi":"10.1007/978-3-030-04807-5_2","DOIUrl":"https://doi.org/10.1007/978-3-030-04807-5_2","url":null,"abstract":"","PeriodicalId":154515,"journal":{"name":"arXiv: Pattern Formation and Solitons","volume":"75 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127195744","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bastián Pradenas, Isidora Araya, M. Clerc, Claudio Falc'on, P. Gandhi, E. Knobloch
{"title":"Slanted snaking of localized Faraday waves","authors":"Bastián Pradenas, Isidora Araya, M. Clerc, Claudio Falc'on, P. Gandhi, E. Knobloch","doi":"10.1103/PhysRevFluids.2.064401","DOIUrl":"https://doi.org/10.1103/PhysRevFluids.2.064401","url":null,"abstract":"We report on an experimental, theoretical and numerical study of slanted snaking of spatially localized parametrically excited waves on the surface of a water-surfactant mixture in a Hele-Shaw cell. We demonstrate experimentally the presence of a hysteretic transition to spatially extended parametrically excited surface waves when the acceleration amplitude is varied, as well as the presence of spatially localized waves exhibiting slanted snaking. The latter extend outside the hysteresis loop. We attribute this behavior to the presence of a conserved quantity, the liquid volume, and introduce a universal model based on symmetry arguments, which couples the wave amplitude with such a conserved quantity. The model captures both the observed slanted snaking and the presence of localized waves outside the hysteresis loop, as demonstrated by numerical integration of the model equations.","PeriodicalId":154515,"journal":{"name":"arXiv: Pattern Formation and Solitons","volume":"709 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126208681","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Aggregation Dynamics Using Phase Wave Signals and Branching Patterns","authors":"H. Sakaguchi, Takuma Kusagaki","doi":"10.7566/JPSJ.85.094801","DOIUrl":"https://doi.org/10.7566/JPSJ.85.094801","url":null,"abstract":"The aggregation dynamics of slime mold is studied using coupled equations of phase phi and cell concentration n. Phase waves work as tactic signals for aggregation. Branching structures appear during the aggregation. A stationary branching pattern appears like a river network, if cells are uniformly supplied into the system.","PeriodicalId":154515,"journal":{"name":"arXiv: Pattern Formation and Solitons","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116077559","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Bright solitons in a PT-symmetric chain of dimers","authors":"O. B. Kirikchi, A. A. Bachtiar, H. Susanto","doi":"10.1155/2016/9514230","DOIUrl":"https://doi.org/10.1155/2016/9514230","url":null,"abstract":"We study the existence and stability of fundamental bright discrete solitons in a parity-time (PT)-symmetric coupler composed by a chain of dimers, that is modelled by linearly coupled discrete nonlinear Schrodinger equations with gain and loss terms. We use a perturbation theory for small coupling between the lattices to perform the analysis, which is then confirmed by numerical calculations. Such analysis is based on the concept of the so-called anti-continuum limit approach. We consider the fundamental onsite and intersite bright solitons. Each solution has symmetric and antisymmetric configurations between the arms. The stability of the solutions is then determined by solving the corresponding eigenvalue problem. We obtain that both symmetric and antisymmetric onsite mode can be stable for small coupling, on the contrary of the reported continuum limit where the antisymmetric solutions are always unstable. The instability is either due to the internal modes crossing the origin or the appearance of a quartet of complex eigenvalues. In general, the gain-loss term can be considered parasitic as it reduces the stability region of the onsite solitons. Additionally, we analyse the dynamic behaviour of the onsite and intersite solitons when unstable, where typically it is either in the form of travelling solitons or soliton blow-ups.","PeriodicalId":154515,"journal":{"name":"arXiv: Pattern Formation and Solitons","volume":"516 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124477836","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Properties of {pi}-mode vibrations in strained carbon chains","authors":"G. Chechin, D. A. Sizintsev, O. Usoltsev","doi":"10.22226/2410-3535-2016-2-146-151","DOIUrl":"https://doi.org/10.22226/2410-3535-2016-2-146-151","url":null,"abstract":"Nonlinear vibrations in strained monoatomic carbon chains are studied with the aid of ab initio methods based on the density functional theory. An unexpected phenomenon of structural transformation at the atomic level above a certain value of the strain was revealed in cumulene chain (carbyne-{beta}). This phenomenon is a consequence of stability loss of the old equilibrium atomic positions that occur at small strain, and appearance of two new stable equilibrium positions near each of them. The aforementioned restructuring gives rise to a softening of {pi}-mode whose frequency tends to zero in a certain region of amplitudes when carbon atoms begin to vibrate near new equilibrium positions. This resembles the concept of soft mode whose \"freezing\" is postulated in the theory of phase transitions in crystals to explain the transitions of displacement type. The dynamical modeling of mass point chains whose particles interact via Lennard-Jones potential can approximate our ab initio results well enough. In particular, this study demonstrates an essential role of dipole-dipole interactions between carbon atoms in formation of their new equilibrium positions in the cumulene chain. We believe that computer studying of Lennard-Jones chains enables to predict properties of various dynamical objects in carbon chains (different nonlinear normal modes and their bushes, discrete breathers etc.) which then can be verified by ab initio methods.","PeriodicalId":154515,"journal":{"name":"arXiv: Pattern Formation and Solitons","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130661664","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Analytical Solutions of Classical and Fractional KP-Burger Equation and Coupled KdV equation","authors":"U. Ghosh, S. Sarkar, S. Das","doi":"10.12921/cmst.2016.0000016","DOIUrl":"https://doi.org/10.12921/cmst.2016.0000016","url":null,"abstract":"Evaluation of analytical solutions of non-linear partial differential equations (both classical and fractional) is a rising subject in Applied Mathematics because its applications in Physical biological and social sciences. In this paper we have used generalized Tanh method to find the exact solution of KP-Burger equation and coupled KdV equation. The fractional Sub-equation method has been used to find the solution of fractional KP-Burger equation and fractional coupled KdV equations. The exact solution obtained by fractional sub-equation method reduces to classical solution when order of fractional derivative tends to one. Finally numerical simulation has done. The numerical simulation justifies that the solutions of two fractional differential equations reduces to shock solution for KP-Burger equation and soliton solution for coupled KdV equations when order of derivative tends to one.","PeriodicalId":154515,"journal":{"name":"arXiv: Pattern Formation and Solitons","volume":"101 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117193249","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Nonlinear vibrational modes in graphene: group-theoretical results","authors":"G. Chechin, D. Ryabov, S. Shcherbinin","doi":"10.22226/2410-3535-2016-1-9-15","DOIUrl":"https://doi.org/10.22226/2410-3535-2016-1-9-15","url":null,"abstract":"In-plane nonlinear delocalized vibrations in uniformly stretched single-layer graphene (space group P6mm) are considered with the aid of the group-theoretical methods. These methods were developed by authors earlier in the framework of the theory of the bushes of nonlinear normal modes (NNMs). We have found that only 4 symmetry-determined NNMs (one-dimensional bushes), as well as 14 two-dimensional, 1 three-dimensional and 6 four-dimensional vibrational bushes are possible in graphene. They are exact solutions to the dynamical equations of this two-dimensional crystal. Prospects of further research are discussed.","PeriodicalId":154515,"journal":{"name":"arXiv: Pattern Formation and Solitons","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115047702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Frozen Fronts Selection in flow against self-sustained chemical waves","authors":"T. Chevalier, D. Salin, L. Talon","doi":"10.1103/PHYSREVFLUIDS.2.043302","DOIUrl":"https://doi.org/10.1103/PHYSREVFLUIDS.2.043302","url":null,"abstract":"Autocatalytic reaction fronts between two reacting species in the absence of fluid flow, propagate as solitary waves. The coupling between autocatalytic reaction front and forced hydrodynamic flow may lead to stationary front whose velocity and shape depend on the underlying flow field. We focus on the issue of the chemo-hydrodynamic coupling between forced advection opposed to self-sustained chemical waves which can lead to static stationary fronts, i.e Frozen Fronts, $FF$. Towards that purpose, we perform experiments, analytical computations and numerical simulations with the autocatalytic Iodate Arsenious Acid reaction ($IAA$) over a wide range of flow velocities around a solid disk. For the same set of control parameters, we observe two types of frozen fronts: an upstream $FF$ which avoid the solid disk and a downstream $FF$ with two symmetric branches emerging from the solid disk surface. We delineate the range over which we do observe these Frozen Fronts. We also address the relevance of the so-called eikonal, thin front limit to describe the observed fronts and select the frozen front shapes.","PeriodicalId":154515,"journal":{"name":"arXiv: Pattern Formation and Solitons","volume":"82 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133353614","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Exactly solvable Wadati potentials in the PT-symmetric Gross-Pitaevskii equation","authors":"I. V. Barashenkov, D. Zezyulin, V. Konotop","doi":"10.1007/978-3-319-31356-6_9","DOIUrl":"https://doi.org/10.1007/978-3-319-31356-6_9","url":null,"abstract":"","PeriodicalId":154515,"journal":{"name":"arXiv: Pattern Formation and Solitons","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115812558","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}