D. Bouchiha | Searcharxiv

arXiv2007

Multiple scattering approach to low-energy electron collisions with the water dimer

Multiple scattering theory is applied to low-energy electron collisions with a complex target formed of two molecular scatterers. The total T-matrix is expressed in terms of the T-matrix for each isolated molecule. We apply the approach to elastic electron-(H2O)2 collisions. Following the method developed in our previous work on crystalline ice, we impose a cut-off on the dipole outside the R-matrix sphere and an energy dependent cut-off on the angular momentum components of the monomer T-matrix. An R-matrix calculation of electron-dimer collisions is performed in order to evaluate the accuracy of the multiple scattering approach. The agreement between the two calculations is very good.

physics.chem-ph↗

arXiv2002

Commensurate-incommensurate transitions of quantum Hall stripe states in double-quantum-well systems

In higher Landau levels (N>0) and around filling factors nu =4N+1, a two-dimensional electron gas in a double-quantum-well system supports a stripe groundstate in which the electron density in each well is spatially modulated. When a parallel magnetic field is added in the plane of the wells, tunneling between the wells acts as a spatially rotating effective Zeeman field coupled to the ``pseudospins'' describing the well index of the electron states. For small parallel fields, these pseudospins follow this rotation, but at larger fields they do not, and a commensurate-incommensurate transition results. Working in the Hartree-Fock approximation, we show that the combination of stripes and commensuration in this system leads to a very rich phase diagram. The parallel magnetic field is responsible for oscillations in the tunneling matrix element that induce a complex sequence of transitions between commensurate and incommensurate liquid or stripe states. The homogeneous and stripe states we find can be distinguished by their collective excitations and tunneling I-V, which we compute within the time-dependent Hartree-Fock approximation.

cond-mat.mes-hall↗