CFTMC  Artículos
http://hdl.handle.net/10486/129154
20201101T02:13:02Z

Zeroenergy pinning from interactions in Majorana nanowires
http://hdl.handle.net/10486/690181
Zeroenergy pinning from interactions in Majorana nanowires
Domínguez, Fernando; Cayao, Jorge; SanJose, Pablo; Aguado, Ramón; Yeyati, Alfredo Levy; Prada, Elsa
Majorana zero modes at the boundaries of topological superconductors are chargeneutral, an equal superposition of electrons and holes. This ideal situation is, however, hard to achieve in physical implementations, such as proximitized semiconducting nanowires of realistic length. In such systems Majorana overlaps are unavoidable and lead to their hybridization into charged Bogoliubov quasiparticles of finite energy, which, unlike true zero modes, are affected by electronic interactions. We here demonstrate that these interactions, particularly with bound charges in the dielectric surroundings, drastically change the noninteracting paradigm. Remarkably, interactions may completely suppress Majorana hybridization around parity crossings, where the total charge in the nanowire changes. This effect, dubbed zeroenergy pinning, stabilizes Majoranas back to zero energy and charge, and leads to electronically incompressible parameter regions wherein Majoranas remain insensitive to local perturbations, despite their overlap
20170301T00:00:00Z

Effects of the electrostatic environment on superlattice Majorana nanowires
http://hdl.handle.net/10486/689988
Effects of the electrostatic environment on superlattice Majorana nanowires
Escribano, Samuel D.; Levy Yeyati, Alfredo; Oreg, Yuval; Prada, Elsa
Finding ways of creating, measuring, and manipulating Majorana bound states (MBSs) in superconductingsemiconducting nanowires is a highly pursued goal in condensed matter physics. It was recently proposed that a periodic covering of the semiconducting nanowire with superconductor fingers would allow both gating and tuning the system into a topological phase while leaving room for a local detection of the MBS wave function. We perform a detailed, selfconsistent numerical study of a threedimensional (3D) model for a finitelength nanowire with a superconductor superlattice including the effect of the surrounding electrostatic environment, and taking into account the surface charge created at the semiconductor surface. We consider different experimental scenarios where the superlattice is on top or at the bottom of the nanowire with respect to a back gate. The analysis of the 3D electrostatic profile, the charge density, the lowenergy spectrum, and the formation of MBSs reveals a rich phenomenology that depends on the nanowire parameters as well as on the superlattice dimensions and the external backgate potential. The 3D environment turns out to be essential to correctly capture and understand the phase diagram of the system and the parameter regions where topological superconductivity is established
20190702T00:00:00Z

DFT molecular dynamics and free energy analysis of a charge density wave surface system
http://hdl.handle.net/10486/689550
DFT molecular dynamics and free energy analysis of a charge density wave surface system
Trabada, Daniel G.; MendietaMoreno, Jesús I.; SolerPolo, Diego; Flores, Fernando; Ortega, José
The K/Si(111):B 3×3 surface, with one K atom per 3×3 unit cell, is considered a prototypical case of a surface Mott phase at room temperature. Our Density Functional Theory (DFT) Molecular Dynamics (MD) and free energy calculations show, however, a 23×3 Charge Density Wave (CDW) ground state. Our analysis shows that at room temperature the K atoms easily diffuse along the lines of a honeycomb network on the surface and that the 3×3 phase appears as the result of the dynamical fluctuations between degenerate CDW states. DFTMD free energy calculations also show a 23×3↔3×3 transition temperature below 90 K. The competing electronelectron and electronphonon interactions at low temperature are also analyzed; using DFT calculations, we find that the electronphonon negativeU * is larger than the electronelectron Hubbard U, indicating that the CDW survives at very low temperature
This Accepted Manuscript will be available for reuse under a CC BYNCND licence after 24 months of embargo period
20190615T00:00:00Z

Proton transfer in guaninecytosine base pairs in bDNA
http://hdl.handle.net/10486/689523
Proton transfer in guaninecytosine base pairs in bDNA
SolerPolo, Diego; MendietaMoreno, Jesús I.; Trabada, Daniel G.; Mendieta, Jesús; Ortega, José
A double proton transfer reaction in a guaninecytosine (GC) base pair has been proposed as a possible mechanism for rare tautomer (G*C*) formation and thus a source of spontaneous mutations. We analyze this system with free energy calculations based on extensive Quantum Mechanics/Molecular Mechanics simulations to properly consider the influence of the DNA biomolecular environment. We find that, although the G*C∗ rare tautomer is metastable in the gas phase, it is completely unstable in the conditions found in cells. Thus, our calculations show that a double proton reaction cannot be the source of spontaneous point mutations. We have also analyzed the intrabase H transfer reactions in guanine. Our results show that the DNA environment gives rise to a large free energy difference between the rare and canonical tautomers. These results show the key role of the DNA biological environment for the stability of the genetic code
This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of Chemical Theory and Computation, copyright © American Chemical Society after peer review and technical editing by the publisher.
To access the final edited and published work see https://pubs.acs.org/doi/10.1021/acs.jctc.9b00757
20191210T00:00:00Z