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We discuss a method for determining the optimally localized set of generalized Wannier functions associated with a set of Bloch bands in a crystalline solid. By ''generalized Wannier functions'' we mean a set of localized orthonormal orbitals spanning the ...
The phonon dispersion curves of cubic acetylene, tetragonal urea, and monoclinic sodium carbonate are calculated from the generic force field using the direct method. The force constants of the dynamical matrix are determined from the forces induced by the ...
A theoretical technique for determining the dispersion relation, the electromagnetic field components, and the quality factor of a dielectric-loaded nonperiodic corrugated waveguide is presented for the case of azimuthally symmetric TM waves, The Floquet t ...
Recent photoemission evidence for non-zero gap in highly overdoped Bi2Sr2-CaCu2O8+x, along the directions in the Brillouin zone where the d-wave gap exhibits nodes, is in accordance with more conventional behavior in strongly overdoped high-T-c cuprates. T ...
We calculate the one-electron Green's function of the two-dimensional (2D) attractive Hubbard model by coupling the electrons to pair fluctuations. The latter are approximated by homogeneous amplitude fluctuations and phase correlations corresponding to th ...
We report results of an angle-resolved high-resolution photoemission study of strongly overdoped Bi2Sr2CaCu2O8+x single crystals with T-c similar to 60 K. We find a nonzero superconducting (SC) gap along all three high symmetry directions in the Brillouin ...
A dynamical theory of multiphoton transitions in semiconductors is developed using a density matrix approach. It is shown that, in dipole approximation, these transitions require a mixed parity of the basis stales and that band-diagonal coupling's of the e ...
We calculate the one-electron spectral function of the attractive (negative-U) Hubbard model. We work in the intermediate-coupling and low-density regime and obtain the self-energy in an approximate analytical form. The excitation spectrum is found to cons ...
Using angle-resolved photoemission, we report the first observation of an incomplete charge-density-wave (CDW) gap opening for the quasi-two-dimensional material Mo4O11. Our data indicate that the gap opening occurs over a range of 0.5 (A)ngstrom(-1) in th ...
Equilibrium geometries and electronic properties of neutral and anionic Cu-n (n = 2, 10) clusters are determined via first-principles calculations which treat s and d electrons on an equal footing. We find cluster shapes similar to those reported in the li ...